| 摘要 |
PURPOSE:To prevent the ascent of the discharge pressure of a charge pump replenishing operation oil to a main hydraulic circuit and reduce load added to an engine in a case in which a brake means is operated at more than a predetermined value regardless of the operation position of an operation means, by making a direction control valve position a neutral position. CONSTITUTION:At a vehicle such as a fork lift, a loading and unloading pump 3, a charge pump 4 and a slant plate type travel hydraulic pump 5 supplying pressure oil to a travel hydraulic motor M, are connected in order with the output shaft 2 of an engine 1. And a charge pipe passage 11 from the pump 4 is made to branch off from between a filter 13 and a charge relief valve 14, and connected to a reinforcement circuit 27 constituted with check valves 25, 26 and relief valves 25a, 26a. In this instance, at a controller 37 inputting the output of a brake operation amount sensor 32a, control in which a direction control valve 16 is set so as to become a neutral position regardless of the operation of a forward/backward motion changeover lever 17, is conducted when a brake operation amount detection value is more than a predetermined value. |
