| 摘要 |
A hydraulic lift tail gate assembly comprises a lifting platform 4 which can be lifted and lowered by means of a lifting cylinder 5 and a positioning cylinder 6 acting on said lifting platform for pivoting the lifting platform between a vertical transport position I, a horizontal platform position II and a downwardly inclined leading position III. In the pressure liquid circuit of the positioning cylinder is connected a control means for sensing the load on the platform and for automatically changing the tilting movement of the lifting platform from a quick movement to a slow one as the load exceeds a predetermined value. A control valve includes a control spindle on which the pressure in the positioning cylinder acts against an adjustable spring load. When the load exceeds the predetermined value, the increased working pressure in the positioning cylinder displaces the control spindle from a free-flow position, in which liquid is allowed to flow from the positioning cylinder through a free flow channel at a higher speed, to a choking position, in which the flow of liquid from the positioning cylinder through a choking channel takes place at a lower speed. <IMAGE> |
