Abstract: A shock absorber for use with a sliding center sill rail car utilizes an internal gas type spring. The shock absorber has a housing and a cylinder located in the housing that moves with the center sill. An annular outer chamber surrounds the cylinder within the housing. Two pistons are slidably carried in the cylinder for independent movement relative to each other. Each has a shaft that extends in opposite directions. The shafts engage stationary stops mounted stationarily to the frame of the rail car. Ports are located in the side wall of the cylinder for the outflow and inflow of a gas and liquid fluid combination. The ports are symmetrical measured either from the rearward end or the forward end.

Abstract: An end-of-car hydraulic pneumatic cushioning device for connecting to the coupler of a railway car having a piston mounted within a cylinder and a piston rod secured to the piston extending rearwardly from the cylinder. The piston divides the cylinder into a front high pressure chamber and a rear low pressure chamber, and a gaseous and liquid fluid mixture is provided in both the high and low pressure chambers. The piston carries normally closed metering valves which open in buff travel a buff flow passage between the low and high pressure chambers after around two inches or more of buff travel from neutral extended position, and open upon return draft travel after buff travel a restricted draft flow passage between the low and high pressure chambers. The gas in the fluid mixture particularly upon high velocity impact loads is dispersed throughout the liquid and thus has a large contact area with the liquid to minimize the increase in temperature of the gas upon being compressed.