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.