GB561802A - Improvements in or relating to hydraulic control apparatus - Google Patents

Abstract

561,802. Hydraulic machines. BROADWAY ENGINEERING CO., Ltd., SELBY, J., and SPUTZ, O. Sept. 30, 1942, No. 13728. [Class 69 (ii) ] [Also in Group XXVI] Control mechanism for a reversible fluidoperated motor, e.g. for operating a shaping machine, comprises a valve 16 moved mechanically by the motor near the end of its stroke to throttle supply of working fluid and thus slow the motor before supply is cut off and a second valve 29 is operated to reverse the supply and exhaust connections. High pressure fluid from a variable delivery pump is supplied to a port 30 in valve 16 for forward movement while low constant pressure fluid is supplied to port 31 for reverse movement. Valve 16 controls the connections between port 30 and main pressure port 32a, throttled pressure 33a and exhaust 34a for forward working, and between port 31 and similar pressure and exhaust ports 32b, 33b, 34b for reverse movement. With valve 16 in the extreme right-hand position and valve 29 as shown, high pressure liquid passes through port 32a and pipe 8 to the motor, while motor exhaust pipe 13 and low-pressure liquid at 31 are connected to exhaust port 39. Near the end of the motor stroke, valve 16 is moved mechanically to the left, first cutting off the main supply 32a and leaving the throttled port 33a open, thus slowing the motor before this port is also closed and the return pressure port 32b opened. At the end of its stroke, valve 16 places the left end of valve 29 in communication with pressure oil supply 43, while the right end is connected to exhaust 48. Valve 29 thus moves rapidly to the right and connects pipe 8 to exhaust 39 while pipe 13 is connected to pressure supply 31 and the motor moves in the reverse direction. At the end of this stroke the whole process is repeated. A hand control valve 52 is used for starting, stopping and inching.