| 摘要 |
1. Loading crane with a swivel arm liftable and lowerable by means of a first hydraulic drive and comprising, if required, a number of further swivel arm elements movable towards one another by means of further hydraulic drives, ahead of the cylinder space (3') of the first hydraulic drive (3) which is associated with an upward motion of the swivel arm (2), a load holding valve (12) being arranged and movable into the open position by pressure increase in the conduit (7) connected with the cylinder space associated with a lowering motion, and an overload valve (11) communicating with the first hydraulic drive and blocking at least the first hydraulic drive against a motion increasing the load moment, when the crane is overloaded, characterized by a spring-loaded compensating valve with two oppositely acting control pistons, the first of said pistons - as known per se - counteracting the spring force and communicating via a first conduit (10) with a cylinder space (3') of the first hydraulic drive (3) associated with a lifting motion of the swivel arm (2), and the second of said pistons, whose direction of action is opposed to the first control piston, being connected with the lowering conduit (7) of the first hydraulic drive (3) via a second conduit (13). |
