A railcar cushioning device includes an elastomeric spring and a hydraulic shock absorber member. The fluid accumulator is located outside of and above the fluid chambers. The accumulator is in communication with the fluid chamber in a non-stroked position, causing entrapped air to be displaced...http://www.google.com.au/patents/US5845796?utm_source=gb-gplus-sharePatent US5845796 - Elastomer spring/hydraulic shock absorber cushioning device
