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 soil or clay load tumbles out. Then the empty scraper returns to the cut site and repeats the cycle.

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).

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.

Grader

A grader, also commonly referred to as a road grader, a blade, a maintainer, or a motor grader, is an engineering vehicle with a long blade used to create a flat surface. Typical models have three axles, with the engine and cab situated above the rear axles at one end of the vehicle and a third axle at the front end of the vehicle, with the blade in between.

In civil engineering, the grader's purpose is to "finish grade" (refine, set precisely) the "rough grading" performed by heavy equipment or engineering vehicles such as scrapers and bulldozers.

Graders can produce inclined surfaces and surfaces with cambered cross-sections for roads. In some countries they are used to produce drainage ditches with shallow V-shaped cross-sections on either side of highways.

Graders are commonly used in the construction and maintenance of dirt roads and gravel roads. In the construction of paved roads they are used to prepare the base course to create a wide flat surface for the asphalt to be placed on. Graders are also used to set native soil foundation pads to finish grade prior to the construction of large buildings.

In some locales such as Northern Europe, Canada, and places in the United States, graders are often used in municipal and residential snow removal. In scrubland and grassland areas of Australia and Africa, graders are often an essential piece of equipment on ranches, large farms, and plantations to make dirt tracks where the absence of rocks and trees means bulldozers are not required. A more recent innovation is the outfitting of graders with GPS technology, such as manufactured by Topcon Positioning Systems, Inc., Trimble Navigation, or [Mikrofyn www.mikrofyn.com] for precise grade control and (potentially) "stakeless" construction.

Capacities range from a blade width of 2.50 to 7.30 m and engines from 93–373 kW (125–500 hp).

Education
The National Association of Heavy Equipment Training Schools (NAHETS), established 2002, uses grader training schools and curriculum as a method to test and train users in the ability of grader use.

M88 Recovery Vehicle

The M88 is one of the largest all weather armored recovery vehicles currently in use by U.S. Armed Forces and Israel Defense Force, almost 10 tons heavier than the M1 Abrams main battle tank. There are currently three variants, the M88, M88A1 and M88A2 Hercules. The M88 series has seen action most noticeably in Vietnam, the Gulf War, Operation Iraqi Freedom, and to a lesser extent during the Kosovo War where they were deployed to help recover heavy armored vehicles of the Allied ground units. The current M88A2 replacement cost is around $2,050,000.

Design
The design of this vehicle was based on the chassis and parts of the automotive component of the M48 Patton and M60 Patton tanks. The original M88 was introduced in 1961, M88A1 in 1977, with the current M88A2 introduced in 1997.

Development
Originally manufactured by Bowen McLaughlin York (later the BMY division of Harsco Corporation) in 1961, the company would later merge with FMC Corp. to form the United Defense Industries in 1994, which was in turn acquired by BAE Systems Land Systems in 2005. In February 2008 the company was awarded a $185 million contract modification from the U.S. Army to manufacture 90 Army-configured M88A2s, four Marine Corps-configured M88A2s and authorized spares list parts.

Role
The M88's primary role is to repair or replace damaged parts in fighting vehicles while under fire, as well as extricate vehicles that have become bogged down or entangled. The main winch on the M88A2 is capable of a 70 ton, single line recovery, and a 140 ton 2:1 recovery when used with the 140 ton pulley. The A-frame boom of the A2 can lift 35 tons when used in conjunction with the spade down. The spade can be used for light earth moving, and can be used to anchor the vehicle when using the main winch. The M88 employs an APU (Auxiliary Power Unit) to provide auxiliary electrical and hydraulic power when the main engine is not in operation. It can also be used to slave start other vehicles, provide power for the hydraulic impact wrench, as well as the means to refuel or de-fuel vehicles as required. The M88 series of vehicles can refuel M1 tanks from its own fuel tanks, but this is a last resort due to the possibility of clogging the AGT-1500's fuel filters. The fuel pump draws fuel from the bottom of the fuel cell, and with it, all of the sediment that has accumulated with time.

Variants
M88 - 1961
M88A1 - 1977
M88A2 Hercules - 1991
While the original M88 and M88A1 are designated as a "Medium Recovery Vehicle", the M88A2 (original designation being M88A1E1) is designated as "Heavy Recovery Vehicles". They are all similar in many fundamental ways however, the later version is distinctly heavier (70 tonnes, compared to the original 56 tonnes) and uses a different engine (AVDS 1790-8CR with 1050 hp, compared to a Continental AVDS-1790-2DR, with 750 hp).

The M88A2 is slightly larger than its predecessors (8.6 x 3.7 x 3.2 m compared to 8.3 x 3.4 x 3.2 m) thus retains a lower top speed (40 km/h) and a significantly lower range (322 km compared to 450 km). There have also been improvements in braking and steering. Additionally, the M88A2 has armoured track skirts, which both previous models lack. The M88 is also lacking in Nuclear Biological and Chemical defences and a smoke screen generator, which the later M88A1 and M88A2 models are equipped with. Furthermore, the crew number has decreased from 5, to 3-4, to 3 through the series.

However, all variants retain the .50 Cal machine gun, 432 mm ground clearance, 2.6 m fording depth, 1.1 m wall climb and 2.6 m trench crossing capabilities. There has been no major deviation in battlefield role through the M88 series, the later models are merely able to lift heavier loads. The M88A1 was designed around the now obsolete M60 Patton tanks, so it was in light of the fact that two M88A1's were required to tow the new M1 Abrams tank that the decision was made to upgrade to the M88A2 in 1991.

Problems
One of the main issues afflicting the current M88A2 is the high rate of winch failures, which is mainly caused by continued winch operation after the cable has wrapped around the drum incorrectly, leading to damaged hub bearings. There is also concern with loss of traction when an M88A2 tows a heavy M1 Abrams on a slope in wet, muddy conditions. The M88A2 was extensively tested at the Aberdeen Proving Grounds, Maryland and on August 10, 1998 was officially approved for the towing of 70-ton combat vehicles such as the M1 Abrams.

M60A1 Armored Vehicle Launched Bridge (AVLB)

The M60A1 AVLB is an armored vehicle used for launching and retrieving a 60 feet (18 m) scissors-type bridge. The AVLB consists of three major sections: the launcher, the hull, and the bridge. The launcher is mounted as an integral part of the chassis. The bridge, when emplaced, is capable of supporting tracked and wheeled vehicles with a military load bearing capacity up to Class 60. The bridge can be retrieved from either end. The roadway width of the AVLB is 12 feet, 6 inches. Bridge emplacement can be accomplished in 2 to 5 minutes, and retrieval can be accomplished in 10 minutes under armor protection.

As of 1996, the U.S. Marines had an inventory of 55 bridges and 37 launchers.

Statistics

General Information
Primary function: Armored vehicle used for launching and retrieving a 60-foot scissors-type bridge.
Manufacturer: General Dynamics Land Systems Division
Contractor: Anniston Army Depot (ANAD)
Power plant: 12 cylinder diesel engine AVOS-1790-20
Power train: CD-850-6A 2 speed forward, 1 reverse
Introduction date: February 1987
Unit Replacement Cost: $749,000

M60A1 Tank Chassis
Weight, combat loaded: 56.6 tons (51.33 metric tons)
Ground clearance: 18 inches (0.4572 meters)
Length: 31 feet (9.44 meters)
Width: 12 feet (3.66 meters)
Maximum speed (governed): 30 miles/hour (48.3 kilometers)
Cross country speed: 8-12 miles/hour (12.88-19.32 km)
Trench crossing: 8.5 feet (2.59 meters)
Range: 290 miles (464 kilometers)
Fuel capacity: 375 gallons (14.19 hectoliters)
Crew: 2 enlisted

Bridge
Length, extended: 63 feet (19.19 meters)
Length, folded: 32 feet (9.75 meters)
Bridge span: 60 feet (18.28 meters)
Width, overall: 13.1 feet (3.99 meters)
Width, roadway: 12.5 feet (3.81 meters)
Width, treadway: 5.75 feet (1.75 meters)
Height, unfolded: 3.1 feet (0.94 meters)
Weight: 14.65 tons (13.28 metric tons)

M9 Armored Combat Earthmover

he M9 (ACE) Armored Combat Earthmover is a highly mobile armored tracked vehicle that provides combat engineer support to front-line forces. Its tasks include eliminating enemy obstacles, maintenance and repair of roads and supply routes, and construction of fighting positions.

The M9 is a highly mobile, armored, amphibious combat earthmover capable of supporting forces in both offensive and defensive operations. It performs critical combat engineer tasks such as digging hull defilade fighting positions for guns, tanks and other battlefield systems to increase their survivability. The ACE breaches berms, prepares anti-tank ditches, prepares combat roads, removes roadblocks and prepares access routes at water obstacles.

The engine, drive train and driver's compartment are laid out in the rear of the vehicle, while the front features an 8.7 cubic yard bowl, apron and dozer blade. Armor consists of welded aluminum with selected steel and aramid-laminated plates. An armored cupola containing eight vision blocks covers the driver's compartment. The vehicle hull is a welded and bolted aluminum structure with a two speed winch capable of 25,000 pound line pull. Towing pintle and airbrake connections are provided. It is equipped with a unique suspension system which allows the front of the vehicle to be raised, lowered, or tilted to permit dozing, excavating, rough grading and ditching functions. In addition, the M9 has armor protection against small arms and artillery fragmentation, a smoke screening capability and chemical-biological protection for the operator. It is capable of 30 MPH road speed, is transportable in C-130, C-141, and C5A aircraft and can swim at 3 MPH under ideal conditions (though with the deletion of the swim mission, swim related components are no longer required to be maintained for the M9 ACE).

By raising the dozer blade and using its scraper blade, the ACE can fill itself with ballast to improve dozing efficiency. Another key feature of the M9 is its unique hydropneumatic suspension system. The principal components are eight high-pressure hydraulic rotary actuators (four on each side) which connect to the roadwheel stations. During high-speed travel, this system assures a smooth ride through the use of shock-absorbing accumulators. In earthmoving operations, the operator rotates the actuators, thus lowering the apron and blade for digging.

A typical combat engineer battalion will contain 22 ACES - seven per company plus an operational readiness float. The active Army has a total of 447 M9 ACEs.