DYNAMICALLY STABLE SPRING SUSPENSION for Railway Cars and Motorcoaches 420128
THIS paper describes an “above-gravity, dynamically stable” spring suspension in which the car or coach is elastically supported at each end on a virtual, universal center bearing on the longitudinal centerline above the center of gravity of the car or coach body. It is pointed out that this virtual support permits sufficient universal swivel action of the truck relative to the car body to account for all operating conditions, and the springs, together with the positioning linkage, cooperate to achieve the desired vibration isolation. The actual car support, however, is at two points on either side of the car centerline with a third attachment below the floor level.
The car or coach body rests on soft coil springs which are recessed into the car structure on either side of the center aisle. These springs carry only vertical load and allow, within limits of safe stress, free horizontal movement of the top relative to the bottom for all lateral and turning movements of the truck in normal service. Lateral movement of the body floating on the main springs is restrained by control arms and links which act on the body above the center of gravity. The longitudinal position of the truck is maintained by the thrust tube or “wagon tongue” which is anchored in rubber at one end of the truck frame and at the other to the car underframe.