| 摘要 |
PROBLEM TO BE SOLVED: To improve the return performance of a handle so as to improve the handle operational feeling by supplying pressure oil to a sub-booster in such a manner as to bypass a main booster by use of an oil leak valve disposed in a supply oil pressure piping upstream from a control valve of a main booster at the time of returning a handle. SOLUTION: On starting to return a handle 27 from the right to the neutral position, according to signals input from a sub-booster operation sensor 64 and sub-booster pressure sensors 65, 66 at the start of return, a control unit 18 rotates a stepping motor 55 to switch an oil leak valve 17. Thus, some of pressure oil supplied from an oil pump 14 to a main booster 12 is directly supplied to a sub-booster 16 in such a manner as to bypass the main booster 12 by the oil leak valve 17 by the above switching operation of the oil leak valve 17. |
