ventilanordning for a double acting hydraulic cylinder for forhindra to vacuum uppstar on one side of the cylinder

摘要

The valve mechanism is for a double-acting ram as used in a loading crane, and whose chambers are supplied alternately by a hydraulic pump. In the pipe (10) acting as the return passage when lowering is a throttle vavle (6), bypassed by a further pipe (11). This incorporates a non-return valve (7) opening in the direction of the ram (8). Supply and return pipes (9, 10) are connected together by a short-circuiting pipe (12), joining the return passage at a point between the throttle valve and that where the bypass pipe (11) joins it. A non-return valve (5) is provided in the short-circuit pipe, opening towards the supply pipe (9) when lowering.