Hydraulic pit prop setting pistol - incorporates valve controlling prop retraction and also controls return flow of hydraulic fluid to tank

摘要

The control valve (8) for a hydraulic pit prop is operated by connection to a setting pistol (1) with an operating lever (3) controlling a 3/2 way valve (5) in one position, hydraulic fluid is discharged by a pump into the working space (6) of the pit prop (67). In a second position, remaining fluid is passed to a return line (19). For retracting the pit prop, the pistol incorporates a second 3/2 way valve (6) which unblocks a check valve (53) within the pit prop. The return line is connected by the pistol to the hydraulic liquid storage tank. ADVANTAGE - Simple control of hydraulic system.