Winding engine

A winding engine is a stationary engine used to control a cable, for example to power a mining hoist at a pit head. Electric hoist controllers that have replaced proper winding engines in modern mining but use electric motors are also traditionally referred to as winding engines.

Most proper winding engines have been stationary steam engines. They differ from most other stationary steam engines in that, like a steam locomotive, they need to be able to stop frequently and also reverse. This requires more complex valve gear and other controls than are needed on engines used in mills or to drive pumps.

From http://en.wikipedia.org/

Wheel tractor-scraper

In civil engineering, a wheel tractor-scraper is a piece of heavy equipment used for earthmoving. The rear part has a vertically moveable hopper (also known as the bowl) with a sharp horizontal front edge. The hopper can be hydraulically lowered and raised. When the hopper is lowered, the front edge cuts into the soil or clay like a cheese slicer and fills the hopper. When the hopper is full (8 to 34 m³ (10 to 45 yd³) heaped, depending on type) it is raised, and closed with a vertical blade (known as the apron). The scraper can transport its load to the fill area where the blade is raised, the back panel of the hopper, or the ejector, is hydraulically pushed forward and the load tumbles out. Then the empty scraper returns to the cut site and repeats the cycle.



On the elevating scraper the hopper is filled by a type of conveyor belt with cutting edges.

Scrapers can be very efficient on short hauls where the cut and fill areas are close together and have sufficient length to fill the hopper. The heavier scraper types have two engines ('tandem powered'), one driving the front wheels, one driving the rear wheels, with engines up to 400 kW (550 horsepower).
A Caterpillar towed scraper parked up

Self propelled scrapers were invented by R. G. LeTourneau in the 1930s. His company called them Tournahoppers.



Two scrapers can work together in a push-pull fashion but this requires a long cut area.

From http://en.wikipedia.org/

Wellhead

A wellhead is a general term used to describe the pressure containing component at the surface of an oil well that provides the interface for drilling and production equipment.

The main purpose of a wellhead is to provide a pressure barrier connecting the casing strings that run from the bottom of the hole sections to the surface pressure control equipment.

Whilst drilling the oil well the surface pressure control is provided by a Blowout preventer or 'BOP'. If the pressure is not contained during drilling operations by the casings, wellhead and BOP, then a well blowout can occur.

Once the well has been drilled, a completion is placed in the well to provide the conduit for the well fluids. The surface pressure control is provided by a christmas tree which is installed on top of the wellhead, and has isolation valves and choke equipment to control the well fluids.

Wellheads can be located on the facility oil platforms/onshore called a surface wellhead, or subsea subsea wellhead/mudline wellhead.

A wellhead system provides the following basic functionality:

* connection for a blowout preventer or bop
* support of the casing and tubing strings (the tubing string may also be suspended in the Christmas tree;
* providing a seal between the different strings;
* allowing for access to annuli between the different casing/tubing strings.

Components

The primary components of a wellhead system are:

* casing head
* casing spools
* casing hangers
* packoffs and isolation seals
* bowl protectors
* test plugs
* mudline suspension systems
* tubing heads
* tubing hangers
* tubing head adapters

Specification

The basic requirements for materials, dimensions, test procedures and pressure ratings for wellheads and wellhead equipment are defined on API Spec 6A: Specification for Wellhead and Christmas Tree Equipment. Wellheads are cemented in place and are generally permanently kept in place, although in exploration wells they may be recovered for use again.

Design factors

Wellheads are manufactured for numerous different purposes.

The main oil industry specifications are :

1. API 6A Specification for Wellhead and Christmas Tree Equipment
2. ISO 10423 Wellhead and Christmas Tree Equipment

Functions

A wellhead serves numerous functions. Some of these are:

1. Means of casing suspension. (Casing is the permanently installed pipe used to line the well hole for pressure containment, collapse prevention, etc.)
2. Means of casing pressure isolation when multiple casing strings are used
3. Means of attaching a blowout preventer during drilling
4. Means of attaching a tree for well control during production, injection, or other operations
5. Means of well access
6. Means of pump attachment
7. Means of tubing suspension (Tubing is removable pipe installed in the well)

From http://en.wikipedia.org/

Trommel

A trommel (from the Dutch word for drum, "trommel") is a screened cylinder used to separate materials by size - for example, separating the biodegradable fraction of mixed municipal waste or separating different sizes of crushed stone.



Portable trommels (also called portable trommel screens) are often used in the production of organic products from various types of waste.

For example, excavation contractors may screen their site debris into two fractions; a saleable topsoil for farms, nurseries and site-work, as well as cleaned rock for aggregates or landscaping work. This allows the contractor to resell their waste, instead of incurring the cost of sending it for disposal.



The same principle applies to the production of compost, sand/gravel, lumber mill by-products and municipal waste.

From http://en.wikipedia.org/

Subsea

Subsea is a general term frequently used to refer to equipment, technology, and methods employed to explore, drill, and develop oil and gas fields that exist below the ocean floors. This may be in "shallow" or "deepwater".

Deepwater is a term often used to refer to subsea projects located in water depths greater than 1,000 feet, and may include floating drill vessels, semi-sub rigs or Semi-submersible Platforms.

"Shallow" or shelf" is used for shallower depths and can include standing Jackup Rigs or similar.

Background and history

Oil and gas fields reside in deep water and shallow water around the world. When they are under water and tapped into for the hydrocarbon production, these are generically called subsea wells, fields, projects, development, or other similar terms.

The first subsea well was in one of the Great Lakes in the USA and was in only a few feet of water.

Systems

Subsea production systems can range in complexity from a single satellite well with a flowline linked to a fixed platform, FPSO or an onshore installation, to several wells on a template or clustered around a manifold, and transferring to a fixed or floating facility, or directly to an onshore installation.

Subsea production systems can be used to develop reservoirs, or parts of reservoirs, which require drilling of the wells from more than one location. Deep water conditions, or even ultradeep water conditions, can also inherently dictate development of a field by means of a subsea production system, since traditional surface facilities such as on a steel-piled jacket, might be either technically unfeasible or uneconomical due to the water depth.

The development of subsea oil and gas fields requires specialized equipment. The equipment must be reliable enough to safe guard the environment, and make the exploitation of the subsea hydrocarbons economically feasible. The deployment of such equipment requires specialized and expensive vessels, which need to be equipped with diving equipment for relatively shallow equipment work (i.e. a few hundred feet water depth maximum), and robotic equipment for deeper water depths. Any requirement to repair or intervene with installed subsea equipment is thus normally very expensive. This type of expense can result in economic failure of the subsea development.

Subsea technology in offshore oil and gas production is a highly-specialized field of application with particular demands on engineering and simulation. Most of the new oil fields are located in deepwater and are generally referred to as deepwater systems. Development of these fields sets strict requirements for verification of the various systems’ functions and their compliance with current requirements and specifications. This is because of the high costs and time involved in changing a pre-existing system due to the specialized vessels with advanced onboard equipment. A full scale test (System Integration Test – SIT) does not provide satisfactory verification of deepwater systems because the test, for practical reasons, cannot be performed under conditions identical to those under which the system will later operate. The oil industry has therefore adopted modern data technology as a tool for virtual testing of deepwater systems that enables detection of costly faults at an early phase of the project. By using modern simulation tools models of deepwater systems can be set up and used to verify the system's functions, and dynamic properties, against various requirements specifications. This includes the model-based development of innovative high-tech plants and system solutions for the exploitation and production of energy resources in an environmentally-friendly way as well as the analysis and evaluation of the dynamic behavior of components and systems used for the production and distribution of oil and gas. Another part is the real-time virtual test of systems for subsea production, subsea drilling, supply above sea level, seismography, subsea construction equipment and subsea process measurement and control equipment.

Remotely Operated Vehicles



Remotely Operated Vehicles (ROV's) are robotic pieces of equipment operated from afar to perform tasks on the sea floor. ROV's are available in a wide variety of function capabilities and complexities from simple "eyeball" camera devices, to multi-appendage machines that require multiple operators to operate or "fly" the equipment.

Organizations

A number of professional societies and trade bodies are involved with the subsea industry around the world. Such groups include Subsea UK, Society of Petroleum Engineers (SPE), American Petroleum Institute (API), American Society of Mechanical Engineers (ASME), National Association of Corrosion Engineers (Nace).

Government agencies administer regulations in their territorial waters around the world. Examples of such government agencies are the Minerals Management Service (MMS, US), Norwegian Petroleum Directorate (NPD, Norway), and Health & Safety Executive (HSE, UK). The MMS administers the mineral resources in the US (using Code of Federal Regulations (CFR)) and provides management of the country's hydrocarbon resources.

Safety

Subsea hydrocarbon (oil and gas) extraction has an exceptionally safe record and has been going on for approximately 100 years.

From http://en.wikipedia.org/

Safety lamp

A safety lamp is any of several types of lamp, which are designed to be safe to use in coal mines. These lamps are designed to operate in air that may contain coal dust, methane, or firedamp, all of which are potentially flammable or explosive. The use of open lamps, rather than the safety lamps that were then available, was one cause of the Naomi Mine explosion and the Darr Mine Disaster in Pennsylvania in December 1907.

First Safe Lamps

The first safety lamp was invented by William Reid Clanny, an Irish physician, who announced his discovery on May 20, 1813 at the Royal Society of Arts in London, but it was not tried out in a colliery until 1815. Within months of this demonstration, two improved designs had been announced: one by George Stephenson, which later became the Geordie lamp, and the Davy lamp, invented by Sir Humphry Davy. Most later lamps are constructed on the principle discovered by Davy, that a flame enveloped in wire gauze of a certain fineness does not ignite firedamp

Both the Davy and Stephenson lamps were fragile. The gauze in the Davy quickly rusted in the moist air of a coal pit, and so became unsafe, while the glass in the Stephenson was easily broken, and could then allow the flame to ignite firedamp in the atmosphere. Later designs, the Gray, Mueseler, Marsaut, and other lamps, tried to overcome these problems by using multiple gauze cylinders, but the glass remained a problem until toughened glass became available.

Also, the light that all these gave was poor and this was not solved until the introduction of electric lighting in mines around 1900. But it took until 1930 for the introduction of battery-powered helmet lamps to finally solve the problem.

Early Illumination



Prior to the invention of these safety lamps, miners used candles with open flames or phosphorescent sources of light and later flint or steel mills designed by 'Spedding.' Later, barometers were used to tell them if atmospheric pressure was low (in which case more methane seeped out of the coal seams into the mine galleries).

The use of small mammals or birds was used much later at the end of the Victorian age to warn of the presence of the deadly carbon monoxide present after underground fires or explosions, the so-called afterdamp. The method was introduced by the noted physiologist and disaster investigator, John Scott Haldane after the Laxey lead mine disaster. Such animals are much more susceptible to the gas, and will die before a human, so giving an early warning of the problem. There were numerous deaths casued by carbon monoxide from a small fire near one of the shaft bottoms. An alternative method of removing a different gas, known as firedamp (methane) involved igniting the gas deliberately to cause explosions, thus evacuating the mines of the majority of explosive or easily flammable material present.

The lack of good lighting was a prime cause of a painful eye affliction (nystagmus).

Modern Lamps

Nowadays, safety lamps are mainly electric, and traditionally mounted on miners' helmets (such as the wheat lamp) or the Oldham headlamp, sealed to prevent gas penetrating the casing and being ignited by electrical sparks.

Although its use as a light source was superseded by electric lighting, the flame safety lamp has continued to be used in mines to detect methane and blackdamp, although many modern mines now also use sophisticated electronic gas detectors for this purpose.

LED safety Lamp

As a new light source, LED has many advantages for safety lamps, including longer burn time and less energy required. Combined with new battery technologies, such as the lithium battery, it gives much better performance in safety lamp applications. It is replacing conventional safety lamps.

From http://en.wikipedia.org/

Pumpjack

A pumpjack (also known as 'nodding donkey, pumping unit, horsehead pump, beam pump, sucker rod pump (SRP), grasshopper pump, thirsty bird and jack pump) is the overground drive for a reciprocating piston pump installed in an oil well.

It is used to mechanically lift liquid out of the well if there is not enough bottom hole pressure for the liquid to flow all the way to the surface. The arrangement is commonly used for onshore wells producing relatively little oil. Pumpjacks are common in many oil-rich areas, dotting the countryside and occasionally serving as local landmarks.

Depending on the size of the pump, it generally produces 5 to 40 litres of liquid at each stroke. Often this is an emulsion of crude oil and water. The size of the pump is also determined by the depth and weight of the oil to be removed, with deeper extraction requiring more power to move the heavier lengths of sucker rods (see diagram at right).

A pumpjack converts the rotary mechanism of the motor to a vertical reciprocating motion to drive the pump shaft, and is exhibited in the characteristic nodding motion. The engineering term for this type of mechanism is a walking beam. It was often employed in stationary and marine steam engine designs in the 1700s and 1800s.

Above ground



Pumpjacks are powered by a "prime mover". This is commonly an electric motor, but combustion engines are used in isolated locations without economic access to electricity. The most common "off-grid" pumpjack engines run on casing gas produced from the well, but pumpjacks have been run on many types of fuel, such as propane (LPG) and diesel. In harsh climates such motors and engines may be housed inside a shack to protect them from the elements.

The prime mover of the pumpjack runs a set of pulleys to the transmission which in turn drives a pair of cranks, generally with counterweights on them to assist the motor in lifting the heavy string of rods. The cranks in turn raise and lower one end of an I-beam which is free to move on an A-frame. On the other end of the beam, there is a curved metal box called a Horse Head or Donkeys Head, named so due to its appearance. A cable made of steel (or, occasionally, fiberglass) called a bridle, connects the horse head to the polished rod, a piston that passes through the stuffing box. The polished rod has a very close fit to the stuffing box, letting it move in and out of the tubing without fluid escaping. (The tubing is a pipe that runs to the bottom of the well through which the liquid is produced.) The bridle follows the curve of the horse head as it lowers and raises to create an almost completely vertical stroke. The polished rod is connected to a long string of rods called sucker rods, which run through the tubing all the way to the down-hole pump, usually positioned near the bottom of the well.

Down-hole



At the bottom of the tubing is the "down-hole pump". This pump consists of two ball check valves: a stationary valve at bottom called the "standing valve", and a valve on the piston connected to the bottom of the sucker rods that travels up and down as the rods reciprocate, known as the "traveling valve". Reservoir fluid enters from the formation into the bottom of the borehole through perforations that have been made through the casing and cement (casing is a larger metal pipe that runs the length of the well, which has cement placed between it and the earth). The tubing, pump and sucker rods are all inside the casing). When the rods at the pump end are traveling up, the traveling valve is closed and the standing valve is open (due to the drop in pressure in the pump barrel). Consequently, the pump barrel fills with the fluid from the formation as the traveling piston lifts the previous contents of the barrel upwards. When the rods begin pushing down, the traveling valve opens and the standing valve closes (due to an increase in pressure in the pump barrel). The traveling valve drops through the fluid in the barrel (which had been sucked in during the upstroke). The piston then reaches the end of its stroke and begins its path upwards again, repeating the process.

Often, gas is produced through the same perforations as the oil. This can be problematic if gas enters the pump, because it can result in "gas locking", where insufficient pressure builds up in the pump barrel to open the valves (due to compression of the gas) and little or nothing is pumped. To preclude this, the inlet for the pump can be placed below the perforations. As the gas-laden fluid enters the well bore through the perforations, the gas bubbles up the annulus (the space between the casing and the tubing) while the liquid moves down to the standing valve inlet. Once at the surface, the gas is collected through piping connected to the annulus.

Water well pump jacks

Pumpjacks can also be used to drive what would now be considered "old fashioned" hand-pumped water wells. The scale of the technology is much smaller than for an oil well, and can typically fit on top of an existing hand-pumped well head. The technology is very simple, typically using a parallel-bar double-cam lift driven from a very low horsepower electric motor.

Although the flow rate for a water well pumpjack is very low compared to a modern jet pump and the lifted water is not pressurized, the water well pumpjack does at least have the option of falling back to hand pumping in an emergency, by simply hand-rotating the pumpjack cam to its lowest position, and attaching a manual handle to the top of the wellhead rod.

From http://en.wikipedia.org/

Power shovel

A Power shovel (also stripping shovel or Front Shovel or Electric Mining Shovel) is a bucket equipped machine, usually electrically powered, used for digging and loading earth or fragmented rock, and mineral extraction.

Design

Shovels normally consist of a revolving deck with a power plant, driving and controlling mechanisms, usually a counterweight, and a front attachment, such as a boom or crane which supports a handle with a digger at the end. The machinery is mounted on a base platform with tracks or wheels. The bucket is also known as the dipper. Modern bucket capacities range from 8 m3 to nearly 80 m3.

Use



Power shovels are used principally for excavation and removal of overburden in open-cut mining operations, though it may include loading of minerals, such as coal. They are the modern equivalent of steam shovels, and operate in a similar fashion.

Operation

The shovel operates using several main motions:

* hoist - pulling the bucket up through the bank (i.e. the bank of material being dug)
* crowd - moving the dipper handle out or in to control the depth of cut and when positioning to dump
* swing - rotating the shovel between digging and dumping
* propel - moving the shovel unit to different locations or dig positions

A shovel's work cycle, or digging cycle, consists of four phases:

* digging
* swinging
* dumping
* returning

The digging phase consists of crowding the dipper into the bank, hoisting the dipper to fill it, then retracting the full dipper from the bank. The swinging phase occurs once the dipper is clear of the bank both vertically and horizontally. The operator controls the dipper through a planned swing path and dump height until it is suitably positioned over the haul unit (e.g. truck). Dumping involves opening the dipper door to dump the load, while maintaining the correct dump height. Returning is when the dipper swings back to the bank, and involves lowering the dipper into the tuck position to close the dipper door.

From http://en.wikipedia.org/

Movement and Surveying Radar

In open pit mining operations, people and equipment are constantly at the base of a steep, man-made slope (the highwall or pit-wall). Instances where this slope fails resulting in a rock or earthfall can result in loss of life, injuries and damage or destruction of equipment (see mining). It has been found that, over the last few hours preceding a slope failure, there is nearly always a small movement, or alteration in the movement pattern in the rock face of that section.


The system is intended to monitor mine slopes to detect this movement and generate a warning of impending failure (slope stability), so that personnel and equipment may be removed prior to the failure. The radar element provides very accurate, real-time, all weather slope movement measurements with sub millimetre detection ability, and is able to provide an alarm if the detected movement reaches a predetermined level, thereby permitting evacuation of the unstable area, and enhancing safety.

All radar measurements are fully geo-referenced to an accuracy that allows easy integration with standard digital terrain mapping (DTM) tools.

A second function of the Movement and Surveying Radar is to determine the absolute range to the electromagnetic reflective centroid of an area on a body of material or geographical feature. This functionality, combined with the accurately surveyed position of the measurement origin of the Movement and Surveying Radar and the positioning system’s angular measurement information, may be used to generate survey data of geographical features such as mine walls and rubble dumps. The survey data collected may be used for applications such as the calculation of material removal volumes.

A Movement and Surveying Radar combines simultaneously the execution of slope stability and surveying measurements, which together with high-speed external data links makes it a near real-time tool for mining safety, planning and productivity improvement.

From http://en.wikipedia.org/

Man engine

A man engine is a mechanism of reciprocating ladders and stationary platforms installed in mines to assist the miners’ journeys to and from the working levels. It was invented in Germany in the 19th century and was a prominent feature of tin and copper mines in Cornwall until the beginning of the twentieth.

Operation



In the Cornish examples the motive power was provided by waterwheels, or one of the mine's beam engines. Originally operating without a flywheel, this offered a reciprocating motion of, typically, twelve to fifteen feet (three to five metres). The engine would be linked to a series of beams – known as "rods" – fastened together and reaching to the bottom of the mineshaft. Small platforms would be attached to the rods at the same distance apart as the engine stroke. Fixed platforms were built onto the shaft walls, spaced to coincide with the top and bottom positions of each of the moving platforms. In a common variation a pair of rods was used, with one on its upstroke as the other descended. The miner hopped from one to the other, rather that waiting at a fixed rest, as they changed direction. Counterweights – large boxes filled with stones attached through "see-sawing" horizontal beams – were installed in order to avoid the full weight of the shaft and men bearing on the engine beam. In the deepest mines, which could sink to more than 350 fathoms (640 metres), extra counterweights were provided in side-shafts at regular intervals.

To go up or down, the miner would step onto the travelling platform and allow himself to be carried to the next fixed platform, where he would step off and wait. At the end of the next stroke the next moving platform would line up and he could step onto it and repeat the process. Although the footholds were often small, grab handles were fitted above each one. Miners may ascend and descend at the same time: the pause at the changeover point is made long enough for two men to change places.

Safety



The miners took to these devices without hesitation as their pay was not calculated until they had reached their underground workplace. Contemporary safety studies concluded that, although intrinsically dangerous, the use of a man engine was in practice safer than climbing long ladders: it was less risky to be carried up at the end of a hard shift than to climb a ladder and risk falling because of exhaustion. In some mines, particularly in Germany, wedges or collars placed just above close-fitting rollers, or chains, were installed to limit any drop should a breakage occur.

Levant mine accident

In the afternoon of 20 October 1919 an accident occurred on the man engine at the Levant Mine, St Just, Cornwall. More than 100 miners were on the engine being drawn to the surface when a metal bracket at the top of the rod broke. The heavy timbers crashed down the shaft, carrying the side platforms with them, and thirty-one men lost their lives. The man engine was not replaced and the lowest levels of the mine were abandoned.

History

The earliest known examples of this device were from the silver mining area of the Harz mountains, Germany, where they were driven by cranks connected to water wheels, although bucket hoists using the same method of operation had been used in Swedish iron mines since the 17th century. They appear to have evolved from an informal modification to the beam pumps, where the miners stuck spikes into the wooden pump rods to get themselves carried up the shaft. As beam pumps were universal in deep mines, it was a then simple development to make proper platforms to carry the miners. The first formal engine was installed in 1833 at a mine at Clausthal, Lower Saxony, where inspector Wilhelm Albert and manager Georg Dörell (1793–1854) fastened foot platforms and hand-holds to adjacent, reciprocating pump rods, using a waterwheel-driven pump put out of use when a new drainage adit was made at a lower level. The 1837 man engine at Grube Samson in Sankt Andreasberg in the same region is still in use, although converted from water to electric power in 1922.

The device was introduced to Cornwall in 1842, following the award of a premium for the best design, by the Royal Cornwall Polytechnic Society. The winner, Michael Loam, built one for the proprietors of the Tresavean Mine, in Lanner near Redruth. He used a double-rod design, driven by a waterwheel. The miners' journey time (in either direction) was reduced from about an hour to twenty-four minutes and output per shift increased by one fifth. More than a dozen examples were installed in Cornish mines by the end of the century, but these were usually of the single-rod type, which was perceived as safer in use.

When cable operated winding gear became available the man engines continued in use, particularly in cases where the mineshaft was not truly vertical and winding engines drawing suspended cages could not be used: with the provision of a few well-place rollers, and “fend offs” mounted on trunnions, the rods could reach the bottom of a shaft even at a substantial deviation from the vertical. Economics also played a part: the rods needed for pumping could be used for this extra function at little increased cost. Even when skips or “kibbles” were used in such shafts, (running on “skipways”) the tipping motion would make them impractical for carrying men.

From http://en.wikipedia.org/

Loader (equipment)

A loader is an engineering vehicle (often used in construction) that is primarily used to "load" material (asphalt, demolition debris, dirt, feed, gravel, logs, raw minerals, recycled material, rock, sand, wood chips, etc.) into or onto another type of machinery (dump truck, conveyor belt, feed-hopper, rail-car, etc.).



Heavy equipment front loaders

A loader (also known as: bucket loader, front loader, front end loader, payloader, scoop loader, shovel, skip loader, and/or wheel loader) is a type of tractor, usually wheeled, sometimes on tracks, that has a front mounted square wide bucket connected to the end of two booms (arms) to scoop up loose material from the ground, such as dirt, sand or gravel, and move it from one place to another without pushing the material across the ground. A loader is commonly used to move a stockpiled material from ground level and deposit it into an awaiting dump truck or into an open trench excavation.

The loader assembly may be a removable attachment or permanently mounted. Often the bucket can be replaced with other devices or tools--for example, many can mount forks to lift heavy pallets or shipping containers, and a hydraulically-opening "clamshell" bucket allows a loader to act as a light dozer or scraper. The bucket can also be augmented with devices like a bale grappler for handling large bales of hay or straw.

Large loaders, such as the Kawasaki 95ZV-2, John Deere 844J, Caterpillar 950H, Volvo L120E, Case 921E, or Hitachi ZW310 usually have only a front bucket and are called Front Loaders, whereas small loader tractors are often also equipped with a small backhoe and are called backhoe loaders or loader backhoes or JCBs, after the company that first invented them.



The largest loader in the world is LeTourneau L-2350. Currently these large loaders are in production in the Longview, Texas facility. The L-2350 uses a diesel electric propulsion system simlilar to that used in a locomotive. Each rubber tired wheel is driven by its own independent electric motor.

Loaders are used mainly for uploading materials into trucks, laying pipe, clearing rubble, and digging. A loader is not the most efficient machine for digging as it cannot dig very deep below the level of its wheels, like a backhoe can. Their deep bucket can usually store about 3-6 cubic meters (exact number varies with the model) of earth. The front loader's bucket capacity is much bigger than a bucket capacity of a backhoe loader. Loaders are not classified as earthmoving machinery, as their primary purpose is other than earthmoving.

Unlike most bulldozers, most loaders are wheeled and not tracked, although track loaders are common. They are successful where sharp edged materials in construction debris would damage rubber wheels, or where the ground is soft and muddy. Wheels provide better mobility and speed and do not damage paved roads as much as tracks, but provide less traction.

In construction areas loaders are also used to transport building materials - such as bricks, pipe, metal bars, and digging tools - over short distances.

Loaders are also used for snow removal, using their bucket or a snowbasket, but usually using a snowplow attachment. They clear snow from streets, highways and parking lots. They sometimes load snow into dump trucks for transport.

High-tip buckets are suitable for light materials such as chip, peat and light gravel and when the bucket is emptied from a height.

Unlike backhoes or standard tractors fitted with a front bucket, many large loaders do not use automotive steering mechanisms. Instead, they steer by a hydraulically actuated pivot point set exactly between the front and rear axles. This is referred to as "articulated steering" and allows the front axle to be solid, allowing it to carry greater weight. Articulated steering provides better maneuverability for a given wheelbase. Since the front wheels and attachment rotate on the same axis, the operator is able to "steer" his load in an arc after positioning the machine, which can be useful. The tradeoff is that when the machine is "twisted" to one side and a heavy load is lifted high, it has a greater risk of turning over to the "wide" side.

Front loaders gained popularity during the last two decades, especially in urban engineering projects and small earthmoving works. Many engineering vehicle manufacturers offer a wide range of loaders, the most notable are those of John Deere, Caterpillar, Case, Volvo, Komatsu, Liebherr,JCB and Kawasaki, being the longest, on-going manufacturer of articulated wheel loaders in the world.

The term "loader" is also used in the debris removal field to describe the boom on a grapple truck.

In Pakistan first tractor loader was manufactured by JIC JIC

Tractor front loaders

These loaders are a popular addition to tractors from 50 to 200hp. It's current 'drive-in' form was originally designed and developed in 1958 by a company called Quicke A history of Quicke loader development.They were developed to perform a multitude of farming tasks, and are popular due to their relavitely low cost (compared to Telehandler) and high versatility. Tractor loaders can be fitted with many attachments such as hydraulic grabs and spikes to assist with bale and silage handling, forks for pallet work, and buckets for more general farm activities.

Compact front end loaders



Popular additions to compact utility tractors and farm tractors are Front End Loaders, also referred to as a FEL. Compact utility tractors, also called CUTs are small tractors, typically with 18 to 50 horsepower (37 kW) and used primarily for grounds maintenance and landscape chores. There are 2 primary designs of compact tractor FELs, the traditional dogleg designed style and the curved arm style.

John Deere Tractor manufactures a semi-curved loader design that does not feature the one piece curved arm, but also is not of the traditional two piece design. New Holland Ag introduced a compact loader with a one piece curved arm on its compact utility tractors, similar one piece curved arm loaders are now available on compact tractors on many brands including Case/Farmall, and some Montana and Kioti tractors. Kubota markets traditional loader designs on most of its compact tractors but now features a semi-curved loader design similar to the John Deere loader design on several of its small tractors.

While the Front End Loaders on CUT size tractors are capable of many tasks, given their relatively small size and low capacities when compared to commercial loaders, the compact loaders can be made more useful with some simple options. A Toothbar is commonly added to the front edge of a loader bucket to aid with digging. Some loaders are equipped with a Quick Attach (QA) system, the QA system allows the bucket to be removed easily and other tools to be added in its place. Common additions would include a set of Pallet Forks for lifting pallets of goods or a Bale Spear for lifting hay bales.

Skid loaders & track loaders



A skid loader is a small loader utilizing four wheels with hydraulic drive that directs power to either, or both, sides of the vehicle. Very similar in appearance and design is the track loader, which utilizes a continuous track on either side of the vehicle instead of the wheels. Since the expiration of Bobcat's patent on its quick-connect system, newer tractor models are standardizing on that popular format for front end attachments.

Unconventional use

Front loaders were sometimes used in ways they weren't ment to, mostly by criminals, but not always.

In 1998 Tom Leask killed one person in city of Alma, Colorado, then used a front loader to demolish several buildings, such as post office, school, water and fire departments. Eventually, he stopped the machine and was arrested by police.

During 2004 bulldozer rampage in Granby, Colorado concrete plant's owner, Code Docheff, used a front loader as weapon against his neighbor, Marvin Heemeyer, who went on rampage for closing the only way to his workshop. Despite attempts to stop bulldozer (trying to rip his tracks off, then ram into engine), Docheff eventually ran from the place after Heemeyer shot several warning shots into loader's scoop.

Front loader was also used in Horsens, Denmark when it was rammed into country's oldest prison's wall. Several prisoners escaped through the hole, but were eventually caught later.



The most infamous use of front loader were two rampages on July 2 and July 22, 2008 in Jerusalem. In the first attack 4 people were killed (including loader's driver), in the second - only the terrorist was killed. On March 5, 2009 another attack occured, with one casualty (loader's driver).



Loaders in popular culture

* In James Bond's fifteenth movie, The Living Daylights, Kamran Shah, leader of the Mujahideen group uses the front loader to demolish Soviet air base.
* Front loaders were almost always the vehicle mode for Constructicon's leader, Scrapper. The only exception is his Transformers Animated incarnation, in which he turns into excavator.

From http://en.wikipedia.org/

Excavator

An excavator is an engineering vehicle consisting of an articulated arm (boom, stick), bucket and cab mounted on a pivot (a rotating platform, like a Lazy Susan) atop an undercarriage with tracks or wheels. Their design is a natural progression from the steam shovel.

Usage

Excavators are used in many ways:

* Digging of trenches, holes, foundations
* Material handling
* Brush cutting with hydraulic attachments
* Forestry work
* Demolition
* General grading/landscaping
* Heavy lift, e.g. lifting and placing of pipes
* Mining, especially, but not only open-pit mining
* River dredging
* Driving piles, in conjunction with a Pile Driver

Configurations

Excavators come in a wide variety of sizes. The smaller ones are called a mini-excavator or compact excavator. One manufacturer's largest model weighs 84,980 kg (187,360 lb) and has a maximum bucket size of 4.5 m³ (5.9 yd³). The same manufacturer's smallest mini-excavator weighs 1470 kg (3240 lb), has a maximum bucket size of 0.036 m³ (0.048 yd³) and the width of its tracks can be adjusted to 89 cm (35 inches). Another company makes a mini excavator that will fit through a doorway with tracks that can be adjusted to only 70 cm (28 inches) wide.

To identify the basic pieces, the cab attaches by way of a pin to the deck which holds the final drives which have a gear that drives the tracks. The Boom attaches to the cab by way of a large pin. Attached to the Boom is the Stick. Attached to the stick is the bucket and optionally, the thumb. Usually 2 large hydraulic cylinders create the lift of the boom. Some booms have a swivel capability so the boom can swing independent of the cab. The stick provides the reach along with the boom. Usually a model of excavator has optional lengths of stick that enhance either reach (longer stick) or break-out power (shorter stick). Bucket sizes and configurations are used for varying purposes. A wide "clean-up" bucket is used in situations where too much dig force would make the surfaces uneven. It "cleans-up" a site smooting and filling the ground. A "dig bucket" is much smaller. It usually has teeth on it to aggressively break into the ground. Buckets have numerous shapes and sizes for various applications. A "V-shaped" bucket can even penetrate ground that is frozen!

Excavator attachments

In recent years, hydraulic excavator capabilities have expanded far beyond excavation tasks with buckets. With the advent of hydraulic powered attachments such as a breaker, a grapple or an auger, the excavator is frequently used in many applications other than excavation. Many excavators feature quick-attach mounting systems for simplified attachment mounting, increasing the machine's utilization on the jobsite. Excavators are usually employed together with loaders and bulldozers. Most wheeled versions, and smaller, compact excavators have a small backfill (or dozer-) blade. This is a horizontal bulldozer-like blade attached to the undercarriage and is used for pushing removed material back into a hole. Prior to the 1990s, all excavators had a hang over, or "conventional" counterweight that hung off the rear of the machine to provide more digging force and lifting capacity. This became a nuisance in tight turn areas - the machine could not swing the second half of its cycle due to restricted turn radius. In the early 1990s The Komatsu Engineering Company launched a new concept excavator line that did away with the "conventional" counterweight design, and so started building the world's first tight tail swing excavators (PC128.PC138,PC228,PC308). These machines are now widely used though out the world.

From http://en.wikipedia.org/

Domestic Canary

The Domestic Canary (Serinus canaria domestica) is a domesticated form of the Wild Canary, a small songbird in the finch family originating from Madeira, the Azores and the Canary Islands.

Canaries were first bred in captivity in the 1600s. They were brought over by Spanish sailors to Europe. Monks started breeding them and only sold the males (which sing). This kept the birds in short supply and drove the price up. Eventually Italians obtained hens and were able to breed the birds themselves. This made them very popular and resulted in many breeds arising and the birds being bred all over Europe.

The same occurred in England. First the birds were only owned by the rich but eventually the local citizens started to breed them and, again, they became very popular. Many breeds arose through selective breeding, and they are still very popular today for their voice.

They come in many colours such as; yellow, orange, brown, black, white, and red. 1 in 65 wild canaries are naturally red.



Varieties



Canaries are generally divided into three main groups: Colorbred Canaries (bred for their many color mutations - Ino, Eumo, Satinette, Bronze, Ivory, Onyx, Mosaic, Brown, etc.), Type Canaries (bred for their shape and conformation - Border, Fife, Gloster, Gibber Italicus, Raza Española, Berner, Lancashire, Yorkshire, Norwich, Australian Plainhead, etc.), and Song Canaries (bred for their unique and specific song patterns - Spanish Timbrado, German Roller, Waterslager (also known as "Malinois"), American Singer, Russian Singer, Persian Singer).

Competitions

In the Northern hemisphere, Canaries are judged in competitions every fall. Shows generally begin in October and November after the breeding season ends. Birds can only be shown by the person who raised them. They all have unique bands on their legs that indicate the year of birth, the unique band number, the club to which the breeder belongs. Some song-breed canaries are judged later in the year (January).

There are many canary bird shows all over the world. The world show (C.O.M.) is held in Europe each year and attracts thousands of breeders. As many as 20,000 birds are brought together for competition.

Miner's canary

Canaries were once regularly used in coal mining as an early warning system. Toxic gases such as carbon monoxide and methane in the mine would kill the bird before affecting the miners. Because canaries tend to sing much of the time, they provided both a visual and audible cue in this respect. The use of so called miner's canaries in British mines was phased out as recently as 1987.

Hence, the phrase "canary in a coal mine" is frequently used to refer to a person or thing which serves as an early warning of a coming crisis. By analogy, the term climate canary is used to refer to a species that is affected by an environmental danger prior to other species, thus serving as an early warning system for the other species with regard to the danger.

Use in research



Canaries have been extensively used in research to study neurogenesis, or the birth of new neurons in the adult brain, and also for basic research in order to understand how songbirds encode and produce song. Thus, canaries have served as model species for discovering how the vertebrate brain learns, consolidates memories, and recalls produces coordinated motor movements. Fernando Nottebohm, a professor at The Rockefeller University detailed the brain structures and pathways that are involved in the production of bird song.

Trivia

* Canaries have been depicted in cartoons from the middle 20th century as being harassed by domestic cats; the most famous cartoon canary is Warner Brothers' "Tweety Bird".

* Norwich City, an English football team is nicknamed 'The Canaries' due to the city once being a famous centre for breeding and export of the birds. The club adopted the colours of yellow and green in homage.

Breeding

Inexperienced breeders find it difficult to determine the sex of canaries by appearance, intensity of colour, or demeanor. Most males sing and most females do not. As spring approaches physical changes are observed in the vent area. The abdomen of the hen becomes more rounded and that of the cock becomes larger and protudes downward in the same direction as the legs.

Canaries are only fertile when the length of the day increases to about 12 hours. This occurs naturally in the spring but can be induced earlier through artificial lighting and heating. Good nutrition is essential. Cuttlefish bone is often used to provide calcium for the formation of egg shells. Liquid vitamin drops help guard against deficiencies. Greens are a staple, such as chickweed, seedy (lawn type) grass heads, dandelion, carrot, broccoli, sprouts, and apple. There are many different recipes for soft food that include ingredients such as hard boiled egg, gelatin, and bread or biscuit crumbs. A protein-rich soft food, together with sprouted seed, is the fundamental diet of canary chicks.

Canaries are best suited to breeding in a controlled environment with one pair per cage. This is essential for any pedigree show varieties. They can also be bred successfully in an avaiary situation if there is sufficient room, excess nesting sites, and a plentiful supply of nesting material.

Males will often be ready to breed before the females. A cock may pursue a hen relentlessly or fight with her. In these situations the pair is separated until the female has most of the nest built and is more likely to accept to the male. Many breeders use a "double breeder" cage with two compartments separated by a removable wire partition. The partition is removed when the pair is observed "kissing" (the male trying to feed the female) through the bars.

An open (uncovered) 4" nest cup is previously installed in an accesible position above the height of the perches. Nesting material such as hessian, plumber's hemp, cotton wool, burlap, and tissue paper is provided.

The hen lays a total of four or five eggs, on successive days. She rarely leaves the nest during the two weeks of incubation and relys on the cock to bring food. Some breeders remove the first two or three eggs and replace them with dummy eggs. They then return the real eggs when the clutch is completed. This causes the eggs to hatch over fewer days and gives a higher survival rate due to less disparity in the size of the chicks. Fresh soft food and sprouted seed is provided regularly until the chicks are weaned to hard seed.

The chicks leave the nest at about 18 days and are fed by the parents for another week or so. The hen then commences a second round and may attack the first one. At this point the partition is returned in a "double breeder" cage so that the fledglings can be housed in one side. Their parents in the other side feed them through the wire while also proceeding with further breeding.

From http://en.wikipedia.org/

Drilling rig

A drilling rig is a machine which creates holes (usually called boreholes) and/or shafts in the ground. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells or they can be small enough to be moved manually by one person. They sample sub-surface mineral deposits, test rock, soil and groundwater physical properties, and also can be used to install sub-surface fabrications, such as underground utilities, instrumentation, tunnels or wells. Drilling rigs can be mobile equipment mounted on trucks, tracks or trailers, or more permanent land or marine-based structures (such as oil platforms, commonly called 'offshore oil rigs' even if they don't contain a drilling rig). The term "rig" therefore generally refers to the complex of equipment that is used to penetrate the surface of the earth's crust.



Drilling rigs can be:

* Small and portable, such as those used in mineral exploration drilling, water wells and environmental investigations.
* Huge, capable of drilling through thousands of meters of the Earth's crust. Large "mud pumps" circulate drilling mud (slurry) through the drill bit and up the casing annulus, for cooling and removing the "cuttings" while a well is drilled. Hoists in the rig can lift hundreds of tons of pipe. Other equipment can force acid or sand into reservoirs to facilitate extraction of the oil or natural gas; and in remote locations there can be permanent living accommodation and catering for crews (which may be more than a hundred). Marine rigs may operate many hundreds of miles or kilometres distant from the supply base with infrequent crew rotation.


From http://en.wikipedia.org/

Dredging

Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location.

This technique is often used to keep waterways navigable. It is also used as a way to replenish sand on some public beaches, where too much sand has been lost because of coastal erosion. Dredging is also used as a technique for fishing for certain species of edible clams and crabs, see fishing dredge.

A dredge is a device for scraping or sucking the seabed, used for dredging. A dredger is a ship or boat equipped with a dredge (though in American usage, there is no added letter).

The process of dredging creates spoils (excess material), which are conveyed to a location different from the dredged area. Dredging can produce materials for land reclamation or other purposes (usually construction-related), and has also historically played a significant role in gold mining. Dredging can create disturbance in aquatic ecosystems, often with adverse impacts.

Uses

* Capital: dredging carried out to create a new harbour, berth or waterway, or to deepen existing facilities in order to allow larger ships access. Because capital works usually involve hard material or high-volume works, the work is usually done using a cutter suction dredge or large trailing suction hopper dredge, but for rock works drilling and blasting along with mechanical excavation may be used.

* Preparatory: work and excavation for future bridges, piers or docks/wharves, often connected with foundation work.

* Maintenance: dredging to deepen or maintain navigable waterways or channels which are threatened to become silted with the passage of time, due to sedimented sand and mud, possibly making them too shallow for navigation. This is often carried out with a trailing suction hopper dredge. Most dredging is for this purpose, and it may also be done to maintain the holding capacity of reservoirs or lakes.

* Land reclamation: dredging to mine sand, clay or rock from the seabed and using it to construct new land elsewhere. This is typically performed by a cutter-suction dredge or trailing suction hopper dredge. The material may also be used for flood or erosion control.

* Beach nourishment: mining sand offshore and placing on a beach to replace sand eroded by storms or wave action. This is done to enhance the recreational and protective function of the beaches, which can be eroded by human activity or by storms. This is typically performed by a cutter-suction dredge or trailing suction hopper dredge.

* Harvesting materials: dredging sediment for elements like gold or other valuable trace substances.

* Seabed mining: a possible future use, recovering natural metal ore nodules from the sea's abyssal plains.

* Construction materials: dredging sand and gravels from offshore licensed areas for use in construction industry, principally for use in concrete. Very specialist industry focused in NW Europe using specialized trailing suction hopper dredgers self discharging dry cargo ashore.

* Anti-eutrophication: Dredging is an expensive option for the remediation of eutrophied (or de-oxygenated) water bodies. However, as artificially elevated phosphorus levels in the sediment aggravate the eutrophication process, controlled sediment removal is occasionally the only option for the reclamation of still waters.

* Contaminant remediation: to reclaim areas affected by chemical spills, storm water surges (with urban runoff), and other soil contaminations. Disposal becomes a proportionally large factor in these operations.

* Removing trash and debris: often done in combination with maintenance dredging, this process removes non-natural matter from the bottoms of rivers and canals and harbors.

Relevance

Without the many and almost non-stop dredging operations world wide, much of the world's commerce would be impaired, often within a few months, since much of world's goods travel by ship, and need to access harbours or seas via channels. Recreational boating also would be constrained to the smallest vessels. The majority of marine dredging operations (and the disposal of the dredged material) will require that appropriate licences are obtained from the relevant regulatory authorities, and dredging is usually carried out by (or for) harbour companies or corresponding government agencies.

Types of dredging vessels

Suction

For suction-type excavation out of water, see Suction excavator.

These operate by sucking through a long tube, like some vacuum cleaners but on a big scale.

A plain suction dredger has no tool at the end of the suction pipe to disturb the material. This is often the most commonly used form of dredging.

Trailing suction

A trailing suction hopper dredger (TSHD) trails its suction pipe when working, and loads the dredge spoil into one or more hoppers in the vessel. When the hoppers are full, the TSHD sails to a disposal area and either dumps the material through doors in the hull or pumps the material out of the hoppers. Some dredges also self-offload using drag buckets and conveyors. The largest trailing suction hopper dredger in the world is currently Jan de Nul's Cristobal Colon (launched July 4, 2008 ); its sister ship Leiv Eriksson is under construction as of the end of 2008 (keel laid August 27, 2008, expected launch July 2009). Main design specs for the Cristobal Colon and the Leiv Eriksson are: 46,000 cubic meter hopper and a design dredging depth of 155 m. Next largest is HAM 318 (Van Oord) with its 37,293 cubic meter hopper and a maximum dredging depth of 101 m.

Cutter suction

A cutter-suction dredger's (CSD) suction tube has a cutter head at the suction inlet, to loosen the earth and transport it to the suction mouth. The cutter can also be used for hard surface materials like gravel or rock. The dredged soil is usually sucked up by a wear-resistant centrifugal pump and discharged through a pipe line or to a barge. In recent years, dredgers with more powerful cutters have been built in order to excavate harder rock without blasting.

The, at this moment, two largest cutter suction dredgers in the world are Deme's D'Artagnan (28,200 kW total installed power) and Jan De Nul's J.F.J. DeNul (27,240 kW). Jan de Nul has by far the most heavy cutters in the market.

Auger suction

This process functions like a cutter suction dredger, but the cutting tool is a rotating Archimedean screw set at right angles to the suction pipe. The first widely used auger dredges were designed by Mud Cat Dredges in the 1980s.

Jet-lift

These use the Venturi effect of a concentrated high-speed stream of water to pull the nearby water, together with bed material, into a pipe.

Air-lift

An airlift is a type of small suction dredge. It is sometimes used like other dredges. At other times, an airlift is used, handheld underwater by a diver. It works by blowing air into the pipe, and that air, being lighter than water, rises inside the pipe, dragging water with it.

Bucket

A bucket dredger is equipped with a bucket dredge, which is a device that picks up sediment by mechanical means, often with many circulating buckets attached to a wheel or chain. Some bucket dredgers and grab dredgers are powerful enough to rip out coral to make a shipping channel through coral reefs.

Grab

A grab dredger picks up seabed material with a clam shell grab, which hangs from an onboard crane or a crane ship, or is carried by a hydraulic arm, or is mounted like on a dragline. This technique is often used in excavation of bay mud. Most of these dredges are crane barges with spuds.

Backhoe/dipper

A backhoe/dipper dredge has a backhoe like on some excavators. A crude but usable backhoe dredger can be made by mounting a land-type backhoe excavator on a pontoon. The three largest backhoe dredgers in the world are Vitruvius and Mimar Sinan (Jan De Nul) and Goliath (Van Oord). They featured barge-mounted excavators. Small backhoe dredgers can be track-mounted and work from the bank of ditches. A backhoe dredger is equipped with a half-open shell. The shell is filled moving towards the machine. Usually dredges material is loaded in barges. This machine is mainly used in harbors and other shallow water.

Water injection

A water injection dredger uses a small jet to inject water under low pressure (to prevent the sediment from exploding into the surrounding waters) into the seabed to bring the sediment in suspension, which then becomes a turbidity current, which flows away down slope, is moved by a second burst of water from the WID or is carried away in natural currents. Water injection results in a lot of sediment in the water which makes measurement with most hydrographic equipment (for instance: singlebeam echosounders) difficult.

Pneumatic

These dredgers use a chamber with inlets, out of which the water is pumped with the inlets closed. It is usually suspended from a crane on land or from a small pontoon or barge. Its effectiveness depends on depth pressure.

Bed leveler

This is a bar or blade which is pulled over the seabed behind any suitable ship or boat. It has an effect similar to that of a bulldozer on land.

Krabbelaar

This is an early type of dredger which was formerly used in shallow water in the Netherlands. It was a flat-bottomed boat with spikes sticking out of its bottom. As tide current pulled the boat, the spikes scraped seabed material loose, and the tide current washed the material away, hopefully to deeper water. Krabbelaar is Dutch for "scratcher".

Snagboat

A snagboat is designed to remove big debris such as dead trees and parts of trees from rivers and canals.

Amphibious

Some of these are any of the above types of dredger, which can operate normally, or by extending legs, also known as spuds, so it stands on the seabed with its hull out of the water. Some forms can go on land.

Some of these are land-type backhoe excavators whose wheels are on long hinged legs so it can drive into shallow water and keep its cab out of water. Some of these may not have a floatable hull and, if so, cannot work in deep water.

* Oliver Evans (1755-1819) in 1804 invented an amphibious dredger which was America's first steam-powered road vehicle.

Submersible

These are usually used to recover useful materials from the seabed. Many of them travel on caterpillar tracks. A unique variant is intended to walk on legs on the seabed.

Fishing

Fishing dredges are used to collect various species of clams scallops, oysters or crabs from the seabed. These dredges have the form of a scoop made of chain mesh, and are towed by a fishing boat. Careless dredging can be destructive to the seabed. Nowadays some scallop dredging is replaced by collecting via scuba diving.

Police drag

In some police departments a small dredge (sometimes called a drag) is used to find and recover objects and bodies from underwater. The bodies may be murder victims, or people who committed suicide by drowning, or victims of accidents. It is sometimes pulled by men walking on the bank.

Disposal of materials

In a "hopper dredger", the dredged materials end up in a large onboard hold called a "hopper." A suction hopper dredger is usually used for maintenance dredging. A hopper dredge usually has doors in its bottom to empty the dredged materials, but some dredges empty their hoppers by splitting the two halves of their hulls on giant hinges. Either way, as the vessel dredges, excess water in the dredged materials is spilled off as the heavier solids settle to the bottom of the hopper. This excess water is returned to the sea to reduce weight and increase the amount of solid material (or slurry) that can be carried in one load. When the hopper is filled with slurry, the dredger stops dredging and goes to a dump site and empties its hopper.

Some hopper dredges are designed so they can also be emptied from above using pumps if dump sites are unavailable or if the dredge material is contaminated. Sometimes the slurry of dredgings and water is pumped straight into pipes which deposit it on nearby land. Other times, it is pumped into barges (also called scows), which deposit it elsewhere while the dredge continues its work.

When contaminated (toxic) sediments are to be removed, or large volume inland disposal sites are unavailable, dredge slurries are reduced to dry solids via a process known as dewatering. Current dewatering techniques employ either centrifuges, large textile based filters or polymer flocculant/congealant based apparatus.

In many projects, slurry dewatering is performed in large inland settling pits, although this is becoming less and less common as mechanical dewatering techniques continue to improve.

Similarly, many groups (most notable in east Asia) are performing research towards utilizing dewatered sediments for the production of concretes and construction block, although the high organic content (in many cases) of this material is a hindrance toward such ends.

Environmental impacts

Dredging can create disturbance to aquatic ecosystems, often with adverse impacts. In addition, dredge spoils may contain toxic chemicals that may have an adverse effect on the disposal area; furthermore, the process of dredging often dislodges chemicals residing in benthic substrates and injects them into the water column.

The activity of dredging can create the following principal impacts to the environment:

* Release of toxic chemicals (including heavy metals and PCB) from bottom sediments into the water column.
* Short term increases in turbidity, which can affect aquatic species metabolism and interfere with spawning.
* Secondary effects from water column contamination of uptake of heavy metals, DDT and other persistent organic toxins, via food chain uptake and subsequent concentrations of these toxins in higher organisms including humans.
* Secondary impacts to marsh productivity from sedimentation
* Tertiary impacts to avifauna which may prey upon contaminated aquatic organisms
* Secondary impacts to aquatic and benthic organisms' metabolism and mortality
* Possible contamination of dredge spoils sites

Major dredging companies

* Inai Kiara Sdn Bhd (Malaysia)
* Weeks Marine (United States)
* Great Lakes Dredging (United States)
* Cashman Dredging and Marine Contracting (United States)
* Ellicott Dredges (United States)
* Royal Boskalis Westminster (Netherlands)
* Jan De Nul (Belgium)
* DEME (Belgium)
* Van Oord Dredging and Marine Contractors (Netherlands)
* IHC Merwede (Netherlands)
* IHC Systems BV (Netherlands)
* Burnham Associates, Inc.(Massachusetts)

Dredging in nature

Some animals have evolved adaptations to find their food by dredging:

* Ducks
* Grey whales: they filter seabed sand with their baleen

From http://en.wikipedia.org/

Dragline excavator

Dragline excavation systems are heavy equipment used in civil engineering and surface mining. In civil engineering the smaller types are used for road and port construction. The larger types are used in strip-mining operations to move overburden above coal, and for tar-sand mining. Draglines are amongst the largest mobile equipment (not water-borne), and weigh in the vicinity of 2000 metric tonnes, though specimens weighing up to 13,000 metric tonnes have also been constructed.

A dragline bucket system consists of a large bucket which is suspended from a boom (a large truss-like structure) with wire ropes. The bucket is manoeuvred by means of a number of ropes and chains. The hoist rope, powered by large diesel or electric motors, supports the bucket and hoist-coupler assembly from the boom. The dragrope is used to draw the bucket assembly horizontally. By skillful manoeuvre of the hoist and the dragropes the bucket is controlled for various operations. A schematic of a large dragline bucket system is shown below.

History

The dragline was invented in 1904 by John W. Page of Page Schnable Contracting for use digging the Chicago Canal. In 1912 it became the Page Engineering Company, and a walking mechanism was developed a few years later, providing draglines with mobility. Page also invented the arched dragline bucket, a design still commonly used today by draglines from many other manufacturers, and in the 1960s pioneered an archless bucket design.

In 1910 Bucyrus International entered the dragline market with the purchase of manufacturing rights for the Heyworth-Newman dragline excavator. Their "Class 14" dragline was introduced in 1911 as the first crawler mounted dragline. In 1912 Bucyrus helped pioneer the use of electricity as a power source for large stripping shovels and draglines used in mining.

In 1914 Harnischfeger Corporation, (established as P&H Mining in 1884 by Alonzo Pawling and Henry Harnischfeger), introduced the world's first gasoline engine-powered dragline. An Italian company, Fiorentini, produced dragline excavators from 1919 licensed by Bucyrus.

In 1939 the Marion Steam Shovel Dredge Company (established in 1880) built its first walking dragline. The company changed its name to the Marion Power Shovel Company in 1946 and was acquired by Bucyrus in 1997. In 1988 Page was acquired by the Harnischfeger Corp., makers of the P&H line of shovels, draglines, and cranes.

Operation



In a typical cycle of excavation, the bucket is positioned above the material to be excavated. The bucket is then lowered and the dragrope is then drawn so that the bucket is dragged along the surface of the material. The bucket is then lifted by using the hoist rope. A swing operation is then performed to move the bucket to the place where the material is to be dumped. The dragrope is then released causing the bucket to tilt and empty. This is called a dump operation.

The bucket can also be 'thrown' by winding up to the jib and then releasing a clutch on the drag cable. This would then swing the bucket like a pendulum. Once the bucket had passed the vertical, the hoist cable would be released thus throwing the bucket. On smaller draglines, a skilled operator could make the bucket land about one-half the length of the jib further away than if it had just been dropped. On larger draglines, only a few extra metres may be reached.

Draglines have different cutting sequences. The first is the side cast method using offset benches; this involves throwing the overburden sideways onto blasted material to make a bench. The second is a key pass. This pass cuts a key at the toe of the new highwall and also shifts the bench further towards the low-wall. This may also require a chop pass if the wall is blocky. A chop pass involves the bucket being dropped down onto an angled highwall to scale the surface. The next sequence is the slowest operation, the blocks pass. However, this pass moves most of the material. It involves using the key to access to bottom of the material to lift it up to spoil or to an elevated bench level. The final cut if required is a pull back, pulling material back further to the low-wall side.

Draglines in mining



A large dragline system used in the open pit mining industry costs approximately US$50-100 million. A typical bucket has a volume ranging from 30 to 60 cubic metres, though extremely large buckets have ranged up to 168 cubic metres. The length of the boom ranges from 45 to 100 metres. In a single cycle it can move up to 450 metric tonnes of material.

Most mining draglines are not diesel-powered like most other mining equipment. Their power consumption is so great that they have a direct connection to the high-voltage grid at voltages of between 6.6 to 22 kV. A typical dragline, with a 55 cubic metre bucket, can use up to 6 megawatts during normal digging operations. Because of this, many (possibly apocryphal) stories have been told about the blackout-causing effects of mining draglines. For instance, there is a long-lived story that, back in the 1970s, if all seven of the Peak Downs (a very large coal mine in central Queensland, Australia) draglines turned simultaneously, they would black out all of North Queensland.

In all but the smallest of draglines, movement is accomplished by "walking" using feet or pontoons, as caterpillar tracks place too much pressure on the ground, and have great difficulty under the immense weight of the dragline. Maximum speed is only at most a few metres per minute since the feet must be repositioned for each step. If travelling medium distances, (about 30-100 km), a special dragline carrier can be brought in to transport the dragline. Above this distance, disassembly is generally required. But mining draglines due to their reach can work a large area from one position and do not need to constantly move along the face like smaller machines.

Limitations

The primary limitations of draglines are their boom height and boom length, which limits where the dragline can dump the waste material. Another primary limitation is their dig depth, which is limited by the length of rope the dragline can utilize. Inherent with their construction, a dragline is most efficient excavating material below the level of their base. While a dragline can dig above itself, it does so inefficiently and is not suitable to load piled up material (as a rope shovel can).

Despite their limitations, and their extremely high capital cost, draglines remain popular with many mines, due to their reliability, and extremely low waste removal cost.

Examples



The coal mining dragline known as Big Muskie, owned by the Central Ohio Coal Company (a division of American Electric Power), was the world's largest mobile earth-moving machine, weighing nearly 13,000 metric tons and standing nearly 22 stories tall. It operated in Guernsey County, in the U.S. state of Ohio from 1969 to 1991, and was powered by 13,800 volts of electricity. It was scrapped in 1999.

The British firm of Ransomes & Rapier produced a few large (1400-1800 ton) excavators, the largest in Europe at the time (1960s). Power was from internal combustion engines driving electric generators. One, named SUNDEW, was used in a quarry from 1957 to 1974. After its working life at the first site in Rutland was finished it walked 13 miles to a new life at Corby; the walk took 9 weeks.

Smaller draglines were also commonly used before hydraulic excavators came into common use, the smaller draglines are now rarely used other than on river and gravel pit works. The small machines were of a mechanical drive with clutches. Firms such as Ruston and Bucyrus made models such as the RB10 which were popular for small building works and drainage work. Several of these can still be seen in the English Fens of Cambridgeshire, Lincolnshire and parts of Norfolk. Ruston's are a company also associated with drainage pumping engines. Electric drive systems were only used on the larger mining machines, most modern machines use a diesel-hydraulic drive, as machines are seldom in one location long enough to justify the cost cost of installing a substation and supply cables.

Technological Advances

Draglines, unlike most equipment used in earth-moving, have remained relatively unchanged in design and control systems for almost 100 years. Over the last few years, some advances in dragline systems and methodologies have occurred.

Automation

Researchers at CSIRO in Australia have a long-term research project into automating draglines and have moved over 250,000 tonnes of overburden under computer control.

Simulation software

Since draglines are typically large, complicated and very expensive, training new operators can be a tricky process. In the same way that flight simulators have developed to train pilots, mining simulator software has been developed to assist new operators in learning how to control the machines.

UDD

UDD stands for Universal-Dig-Dump. It represents the first fundamental change to draglines for almost a century, since the invention of the 'miracle hitch'. Instead of using two ropes (the hoist rope and the drag rope) to manipulate the bucket, a UDD machine uses three ropes, two hoist and one drag. This allows the dragline operator to have much greater selectivity in when to pick up the bucket, and in how the bucket may be dumped. UDD machines generally have higher productivity than a standard dragline, but often have greater mechanical issues. Within the mining industry, there is still much debate as to whether UDD improvements justify their costs.

From http://en.wikipedia.org/

Bucket-wheel excavator

Bucket-wheel excavators are heavy equipment used in surface mining and civil engineering. They are among the largest vehicles ever constructed, and the biggest bucket-wheel excavator ever built, the MAN Takraf RB293, is the largest terrestrial vehicle in human history.



Operation

The excavation component itself is a large rotating wheel mounted on an arm or boom. On the outer edge of the wheel is a series of scoops or buckets. As the wheel turns, the buckets remove soil or rock from the target area and carry it around to the backside of the wheel, where it falls onto a conveyor, which carries it up the arm toward the main body of the excavator. Additional conveyors then may carry it further; in some cases, several long conveyors are placed end-to-end, each supported by a large vehicular base, usually with caterpillar tracks.



Size

The largest bucket-wheel excavators in the world are used in German strip-mining operations. These tremendous earth-movers can cost over $100 million, take 5 years to assemble, require 5 people to operate, weigh more than 13,000 short tons (12,000 t), and have a daily capacity of 240,000 short tons (220,000 t) of brown coal or m³ overburden. One of them, Bagger 288, is working in stripmine Garzweiler (Tagebau Garzweiler), and five others in stripmine Hambach (among them Bagger 293). Bagger 288 (the oldest, assembly completed in 1978) is 240 metres (790 ft) long and 96 metres (310 ft) high. Until 2001 it worked in Hambach, and then drove as a giant caterpillar vehicle to Garzweiler, a distance of 22 kilometres (14 mi) through the fields, crossing a few roads, a railroad, and a river. Bagger 293 (formerly RB293, manufactured by Tenova Takraf), the heaviest among these 240,000ers, was recognised by the Guinness Book of Records (2001–2009) as the largest and heaviest land vehicle.

RB293 was the name given by former brown coal company Rheinbraun to their biggest excavator; Rheinbraun's successor RWE calls it simply Bagger 293; and manufacturer Tenova Takraf generally refers to it as an excavator of the type SRs 8000.

From http://en.wikipedia.org/

Beam engine

A beam engine is a design of engine based on the principles of a first-class lever. A force is applied to one end of a beam, which is pivoted in the middle, and the lever action transfers the force to create work at the other end of the beam.

The most familiar example is the type of stationary steam engine used for pumping water from mines. Here the piston of a vertically-mounted cylinder is attached to one end of the beam, to apply the force through upward and/or downward motion. The other end of the beam is connected to a vertically-acting pump. A downward pull on the piston causes the other end of the beam to lift whatever is attached to it, thereby doing 'work'.

The most common engine was the stationary steam-driven type, but water, wind or other forms of propulsion could be used.

Beam engines need not be 'stationary'. The steamboat Eureka is still powered by its rotative beam engine.



History

The first beam engines were water-powered, and used to pump water from mines. A 'preserved' example may be seen at Wanlockhead, in Scotland.

Beam engines were extensively used to power pumps on the English canal system when it was expanded by means of locks early in the Industrial Revolution, and also to drain water from mines in the same period, and as winding engines.

The first steam-powered beam engine was developed by Thomas Newcomen. The Newcomen steam engine was adopted by many mines in Cornwall and elsewhere, but it was relatively inefficient and consumed a large quantity of fuel. James Watt resolved the main inefficiencies of the Newcomen engine in his Watt steam engine, and these beam engines were used commercially in much larger numbers.

Watt held patents on key aspects of his engine's design, and it was not until these patents expired that others could develop modifications to improve it. The beam engine was considerably improved and enlarged in the tin- and copper-rich areas of south west England, which enabled the draining of the deep mines that existed there. Consequently the Cornish beam engines became world famous, as they remain the most massive beam engines ever constructed.

Rotative beam engines

In a rotative beam engine, the piston is mounted vertically, and the piston rod does not connect directly to the connecting rod, but instead to a rocker or beam above both the piston and flywheel. The beam is pivoted in the middle, with the cylinder on one side and the flywheel, which incorporates the crank, on the other. The connecting rod connects to the opposite end of the beam to the piston rod, and then to the flywheel.

Early Watt engines used Watt's patent sun and planet gear, rather than a simple crank, as use of the latter was protected by a patent owned by someone else. Once the patent had expired, the simple crank was employed universally.

Compounding

Compounding involves two or more cylinders; waste low-pressure steam from the first, high-pressure, cylinder is passed to the second cylinder where it expands further and provides more drive. This is the compound effect; the waste steam from this can produce further work if it is then passed into a condenser in the normal way. The first experiment with compounding was conducted by Jonathan Hornblower, who took out a patent in 1781. His first engine was installed at Tincroft Mine, Cornwall. It had two cylinders – one 21-inch (0.53 m) diameter with 6-foot (1.8 m) stroke and one 27-inch (0.69 m) diameter with 8-foot (2.4 m) stroke – placed alongside each other at one end of the beam. The early engines showed little performance gain: the steam pressure was too low, interconnecting pipes were of small diameter and the condenser ineffective.

At this time the laws of thermodynamics were not adequately understood, particularly the concept of absolute zero. Engineers such as Arthur Woolf were trying to tackle an engineering problem with an imperfect understanding of the physics. In particular, their valve gear was cutting-in at the wrong position in the stroke, not allowing for expansive working in the cylinder. Successful Woolf compound engines were produced in 1814, for the Wheal Abraham copper mine and the Wheal Vor tin mine.Here, the cut-off problem had been solved but the engines were compromised by being single-acting: both cylinders driving the same shaft. This action was improved by Galloways of Manchester, whose horizontal side-by-side compound arrangement was patented in 1873.

McNaught engines



William McNaught of Glasgow, not to be confused with William McNaught of Rochdale (Petrie and McNaught), patented a compound beam engine in 1845. On a beam engine of the standard Boulton & Watt design he placed a high-pressure cylinder, on the opposite side of the beam to the existing single cylinder, where the water pump was normally fitted. This had two important effects: it massively reduced the pressure on the beam, and the connecting steam pipe, being long, acted as an expansive receiver – the element missing in the Woolf design. This modification could be made retrospectively, and engines so modified were said to be "McNaughted". The advantages of a compound engine were not significant at pressures under 60psi, but showed at over 100psi.

From http://en.wikipedia.org/

Air classifier

An air classifier is an industrial machine which sorts materials by a combination of size, shape, and density. It works by injecting the material stream to be sorted into a chamber which contains a column of rising air. Inside the separation chamber, air drag on the objects supplies an upward force which counteracts the force of gravity and lifts the material to be sorted up into the air. Due to the dependence of air drag on object size and shape, the objects in the moving air column are sorted vertically and can be separated in this manner.

Air classifiers are commonly employed in industrial processes where a large volume of mixed materials with differing physical characteristics need to be sorted quickly and efficiently. One such example is in recycling centers, where various types of metal, paper, and plastics arrive mixed together and need to be sorted before further processing can take place.

From http://en.wikipedia.org/

Archimedes' screw

Archimedes' screw, the Archimedes screw, the Archimedean screw or the screwpump is a machine historically used for transferring water from a low-lying body of water into irrigation ditches. It was one of several inventions and discoveries traditionally attributed to Archimedes in the 3rd century BC.

The Archimedes' Screw consists of a screw inside a hollow pipe. The screw is turned usually by a windmill or by manual labor. As the bottom end of the tube turns, it scoops up a volume of water. This amount of water will slide up in the spiral tube as the shaft is turned, until it finally pours out from the top of the tube and feeds the irrigation systems.



The contact surface between the screw and the pipe does not need to be perfectly water-tight because of the relatively large amount of water being scooped at each turn with respect to the angular frequency and angular speed of the screw. Also, water leaking from the top section of the screw leaks into the previous one and so on, so a sort of mechanical equilibrium is achieved while using the machine, thus preventing a decrease in mechanical efficiency.



The invention of the water-screw is credited to Archimedes of Syracuse in the 3rd century BC. Its tentative attribution to the 6th century BC Babylonian king Nebuchadnezzar II by the assyriologist Dalley has been refuted on the grounds of "the total lack of any literary and archaeological evidence for the existence of the water-screw before ca. 250 BC". A screw can be thought of as an inclined plane wrapped around a cylinder.

The "screw" does not necessarily need to turn inside the casing, but can be allowed to turn with it in one piece. In ancient times people ran on the screw to turn them. A screw could be sealed with Pitch resin or some other adhesive to its casing, or, cast as a single piece in bronze, as some researchers have postulated as being the devices used to irrigate Nebuchadnezzar II's Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World. Depictions of Greek and Roman water screws show the screws being powered by a human treading on the outer casing to turn the entire apparatus as one piece, which would require that the casing be rigidly attached to the screw.



The design of the everyday Greek and Roman water screw, in contrast to the heavy bronze device of Sennacherib, with its problematic drive chains, has a powerful simplicity. A double or triple helix was built of wood strips (or occasionally bronze sheeting) around a heavy wooden pole. A cylinder was built around the helices using long, narrow boards fastened to their periphery and waterproofed with pitch



Along with transferring water to irrigation ditches, this device was also used for "stealing" land from under sea level in the Netherlands and other places in the creation of polders. A part of the sea would be enclosed and the water would be pushed up out of the enclosed area, starting the process of draining the land for use in farming. Depending on the length and diameter of the screws, more than one machine could be used to successively lift the same water.

Archimedes screws are used in sewage treatment plants because they cope well with varying rates of flow and with suspended solids. An auger in a snow blower or grain elevator is essentially an Archimedes screw.

The principle is also found in pescalators, which are Archimedes screws designed to lift fish safely from ponds and transport them to another location. This technology is primarily used at fish hatcheries, where it is desirable to minimize the physical handling of fish.

Types

Screw conveyor



A screw conveyor is an Archimedean screw contained within a tube and turned by a motor so as to deliver material from one end of the conveyor to the other. It is particularly suitable for transport of granular materials such as plastic granules used in injection moulding, and cereal grains. It may also be used to transport liquids. In industrial control applications the conveyor may be used as a rotary feeder or variable rate feeder to deliver a measured rate or quantity of material into a process.

From http://en.wikipedia.org/