Fluid operated ram

Abstract

The invention is concerned with an improved fluid operated hydraulic ram wherein the travel of the piston thereof is cushioned to reduce impact by progressively restricting fluid flow. The ram of the invention comprises a housing defining a generally cylindrical ram bore having a first wall at a first end thereof with a first hole generally centrally therethrough and a second wall at a second end thereof with a second hole generally centrally therethrough leading to a chamber. A piston fits reciprocally within the ram bore and includes a piston rod extending therefrom through the first hole and a snubber extending from the opposite side thereof towards the second hole. The snubber is sized to pass into the second hole in spaced flow restrictive relation thereto towards the chamber to create a relatively higher pressure in the ram bore adjacent the second end thereof than in the chamber. A valve forms a part of the ram, the valve being adapted to pass a first fluid flow from a first conduit which communicates with the chamber to a sump. A second conduit communicates a second fluid flow from the second end of the ram bore with the valve to adjust the valve to meter the amount of the first fluid flow. A third conduit communicates with the ram bore adjacent the first wall and a pump is provided which causes a third fluid flow from the sump selectively to either the first or third conduit.