Hydraulic actuating unit, in particular for raising a load, such as a hospital bed

Abstract From the Canadian patent

A hydraulic actuating unit for raising a hospital bed includes a reservoir, a hydraulic piston cylinder device the cylinder of which has its ends con-nected to the reservoir through a supply conduit that contains a hydraulic plunger pump with suction and pressure valve means and through a return conduit which contains an orifice in a normally closed relief valve. A branch conduit leads to a hydraulic liquid accumulator from the supply conduit at a location between the cylinder and pressure valve means. A multiple pilot operated check valve of the differential type is provided in the branch conduit towards the accumulator. The largest and smallest end faces of the differential spool member …