Patent ID: 7996939

Claim:
A hydraulically powered lift ambulance cot comprising: a wheeled base having a first slide member slidably supported by a longitudinally extending lower guide; a support frame having a second slide member slidably supported by a longitudinally extending upper guide, said support frame is disposed above said wheeled base; a support mechanism which supports said support frame relative to said wheeled base, said support mechanism is pivotably connected to said support frame, said wheeled base, said first slide member, and said second slide member; wherein said support mechanism is an x-frame that includes a first pair of parallel legs and a second pair of parallel legs, respective ones of the pairs of legs are pivotably connected at an intermediate location by a pivot brace; a hydraulic lift system pivotably mounted at a first end to said first slide member, and at a second end to said support mechanism, said hydraulic system comprising: at least one cylinder for vertically adjusting the ambulance cot; a power unit having a bi-directional pump; a control circuit having a first branch in fluid connection with both the pump and an extension side of the at least one cylinder at a first location, a second branch in fluid connection with both the pump and a retraction side of the at least one cylinder at a second location, the first and second locations being on opposite sides of a piston dividing the at least one cylinder into the extension side and the retraction side, and a pair of hand-operated spring-return valves in fluid connection between the first and second branches; and a battery provided to said cot to supply electricity to the hydraulic lift system in order to assist relative movement between said support frame and said wheeled base.