AAR type A switcher truck

EMD AAR Type A bogie trucks 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 Blomberg at EMD and the originating foundry General Steel Castings; see U.S. Patent 2,137,074 filed 1937Jul06 then granted 1938Nov15. Intended for industrial plant and rail yard shunting duty, this bogie truck has a basic suspension system with drop equalizers, secondary leaf springs and primary coil springs, which provide adequate damping and relatively simplified maintenance; it does not have swing hangers as may be seen in higher-speed designs such as the EMD Blomberg. As of this 2019 writing, these bogie trucks remain in revenue service on operating locomotives in North America.

EMD#AARA
Bogie Trucks

Wheel sets on this bogie truck are typically 56.5 inch (1.435 m) standard gauge with 40 inch (1.016 m) tread diameters; wheel base is 96 inch (2.438 m); early builds have Plain#6.500x12 journal bearings allowing 62750 Lbs (28.46 tonne) Axle GRL; later builds have APcGG#6.500x12 conical bearings allowing 70000 Lbs (31.75 tonne) Axle GRL; various gears and trac motors (EMD#D17+D27+D37+D47+D57+D77+D78...) have been used, though rebuilds typically have a 62tAxleBull~15tMotorPinion gear ratio and EMD#D78 motors; maximum stable speed is typically 45 MpHr (72 KpHr).

See also


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