Hydraulic control for a simple hydraulic engine - has a spring controlling the pressure limiter housed in a separate cartridge

摘要

A servo slide valve (28) in a housing (14) has a neutral and two or more operation positions for the supply of pressure medium to an engine and unloading for reverse. Between the slide valve (28) and engine connection is a block (13) with a longitudinal drill (45) containing a non-return valve (52) and associated piston (49). The block (13) incorporates a pressure limiting valve (67) to protect a primary engine compartment (23). The drill (45) is divided into three sections by two engine compartments (23,24). The central section (46) contains an outlet chamber (48) and the pressure limiting controller (49). The spring (63) of the pressure limiting valve (67) is located in a separate part of the housing (14) from the piston and controller, and is contained in a cartridge (61). The spring (63) operates in conjunction with the controller (49). ADVANTAGE - Simple and cheap to produce; external adjustment of pressure-limiting valve.