Mechanical digger lifting jack with safety device - monitors pressure after flexible pipeline section to control automatic non-return valve which can be selectively inhibited

摘要

The pack is used with a flexible pipeline exposed to accidental rupture and has a safety device. The safety valve uses a non-return valve controlled automatically which is inserted between the flexible pipeline and the jack cylinder. The control device for the valve is designed to be fail-safe and is responsive to the press. present within a supply conduit at a point between the non-return valve and the flexible pipeline. Pref. a two-position valve, controlled by the press. at the latter point in the supply conduit, controls the automatic closure of the non-return valve. The two-position valve may be controlled hydraulically, or it may comprise an electromagnetic valve receiving the output of an electrical press. sensor inserted in the supply conduit. The safety device is designed for a double action hydraulic jack for lifting and lowering operations.