AAR Type A

truck A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...

s were first introduced with EMD locomotives sold in 1935; they were a success, became standard on EMD switchers into the 1970s, and were also used on various other makers' locomotives. Their initial design was a collaboration between

Martin P Blomberg Martin Petrus Frederik Blomberg (December 11, 1888 in Östervåla, Sweden — March 29, 1966 in Winter Park, Florida) was an American engineer of Swedish origin. He became well known for the development of the truck frame for the diesel-electric ...

at EMD and the originating foundry

General Steel Industries General Steel Industries, Inc. (GSI) was an American steel company founded as General Steel Castings Corporation in 1928. The company's first headquarters were in Eddystone, Pennsylvania and, prior to completing its own modern steel foundry in ...

. Intended for industrial plant and rail yard shunting duty, this truck has a basic suspension system with drop equalizers, secondary

leaf springs A leaf spring is a simple form of spring commonly used for the suspension in wheeled vehicles. Originally called a ''laminated'' or ''carriage spring'', and sometimes referred to as a semi-elliptical spring, elliptical spring, or cart spring, it ...

and primary

coil spring A selection of conical coil springs The most common type of spring is the coil spring, which is made out of a long piece of metal that is wound around itself. Coil springs were in use in Roman times, evidence of this can be found in bronze Fib ...

s, which provide adequate

damping Damping is an influence within or upon an oscillatory system that has the effect of reducing or preventing its oscillation. In physical systems, damping is produced by processes that dissipate the energy stored in the oscillation. Examples incl ...

and relatively simplified maintenance. It does not have swing hangers as may be seen in higher-speed designs such as the

Blomberg B The Blomberg B is a 2-axle bogie that was introduced by EMD in 1939 with the FT locomotive series; the original "B" version plus later "M" and "X" versions were quite successful and became standard equipment on a multitude of locomotive models. ...

See also