| 摘要 |
PURPOSE:To prevent push-out force from dropping, which is frequently observed between rear stage cylinders of multistage cylinder type, by allowing an hydraulic cylinder unit, which drives an earth-moving plate to push out earth and sand, to comprise two sets of cylinders which make expansion and contraction actions in opposite directions. CONSTITUTION:An hydraulic cylinder unit S comprises a pair of cylinders S1 and S2, and two pairs of cylinders s1 and s2 which expand and contract in opposite directions to a base cylinders S0 (s0). When oil is supplied under pressure to the hydraulic cylinder unit S, expansion pipes S1 and s1 start elongation simultaneously. When the expansion pipes S1 and s1 have reached the limit of elongation, the base cylinders S1 and s1 move by the elongation of the expansion pipe s1. When the pressurized oil is further supplied, the expansion pipes S2 and s2 simultaneously elongate. At this stage, the expansion pipes S1 and (s1) scarcely reduce the pressure-receiving area to the expansion pipes S1 and s1, which allows a sufficient actuating force to be exerted. |
