Safety control for spectacle assembly jack system - uses pressurised fluid distributor with intermediate position ensuring fluid flows to discharge outlet

摘要

A fluid under pressure is applied to a distribution unit (18) which comprises a slide valve (18) operating in a body (20). The valve has several passages (21) which are arranged to communicate with the pipes (22) of a jack (10) and with the high pressure inlet (A) and discharge (D) to the atmosphere. The valve is positioned by a hand control (17) which has a stop position which immobilises the system at an intermediate position for the displacement of the jack piston (11). This position ensures that the fluid is connected from the jack to the discharge pipes. This prevents injury to the user if a hand is placed in the operating area. A spring (26) on the shaft (13) between the jack body and a support flange (27) at the end of the shaft tends to move the piston permanently to one end of its travel away from the operating position.