| 摘要 |
PCT No. PCT/JP83/00071 Sec. 371 Date Nov. 7, 1983 Sec. 102(e) Date Nov. 7, 1983 PCT Filed Mar. 8, 1983 PCT Pub. No. WO83/03127 PCT Pub. Date Sep. 15, 1983.A hydraulic circuit construction for a tractor having a hydraulic stepless change speed apparatus wherein pressure oil is supplied to the charge oil line regardless of whether the main clutch is engaged or disengaged while the engine is running. Furthermore, where the lift arm cylinder is the single acting type, the pressure oil from the hydraulic pump directly connected to the engine is divided at a flow priority valve, its excess flow being supplied to the hydraulic circuit for driving the lift arm cylinder, into a return oil line from this circuit a control flow of the flow priority valve being joined, whereby at least a constant amount of control flow is supplied to the charge oil line to avoid a complete break of the charge oil supply even if there is no flow of pressure oil in the return oil line at times of pressure oil supply to the single acting lift arm cylinder. |
