GB1515914A - Load responsive control valve assembly - Google Patents

Abstract

1515914 Valves T BUDZICH 18 May 1975 19297/75 Heading F2V In a multi-way valve assembly 10 for supplying operating fluid to and from a motor 11, a by-pass return valve 40 is provided at the inlet side of the assembly and a throttling valve 29 is provided at the outlet side. Assuming the main valve spool 16 is moved to the right from its neutral position shown to connect inlet chamber 21 with load chamber 22, and load chamber 23 with exhaust 34 via outlet chamber 25, throttle means 64 and valve 29 then, under normal positive-load conditions, the valve 40 will open sufficiently to maintain a predetermined pressure drop between chambers 21 and 22, and the valve 29 will remain fully open as shown. If the loading on the motor should change to negative then the pressure in chamber 22 will fall and this will be sensed in loading space 43 causing the return valve 40 to open further to maintain the said pressure drop constant. Moreover, the pressure in chamber 23 will rise causing the valve 29 to throttle the outflow and maintain a constant pressure drop across the throttle means 64. Thus the desired speed of the motor will be maintained. An alternative of throttling valve is described with reference to Fig. 3 (not shown). In a system incorporating two motors and two valve assemblies (Fig. 4), a throttling valve (95) is additionally provided at the inlet side of one of the valve assemblies to ensure that both motors are suitably controlled even if one of them should be subjected to greater loading.