Abstract: To prevent rapid collapse of a hydraulic lift mechanism in event of the failure of the hydraulic mechanism (e.g. as by rupture of a pressurized hydraulic line) a rate of flow responsive check valve is provided, either in a separate backup cylinder or at the inlet-outlet port of the lift cylinder, to close off the return flow path of the hydraulic line in the event of sudden depressurization of the hydraulic feed line or other pressure failure in the hydraulic liquid. In normal operation, the check valve does not oppose the return flow since the rate of such flow is insufficient to activate the valve.

Abstract: A liquid spring shock absorber is provided with an improved piston head-piston rod assembly free of stress force concentrating design features. The shock absorber assembly further includes a slidably extending member for the accomodation of tension loads.