| 摘要 |
In a loading crane comprising a crane post on which is pivotally mounted a crane arm or boom, and a main hydraulic piston-and-cylinder unit the lower end of which is pivotally connected to the base of the crane post and the upper end of which is pivotally connected to the inner crane arm end to effect raising and folding movements of said arm, a device, preferably in the form of an auxiliary piston-and-cylinder unit, arranged to displace the upper fulcrum of the main cylinder unit away from the crane post, past an imaginary line extending between the fulcrum pin on which the crane arm pivots relative to said post and the lower fulcrum point of the main cylinder unit. |
