| 摘要 |
<p>PURPOSE:To prevent a clutch from slips and damages while maintaining a overriding property satisfactorily by providing throttle flow paths for affording communication between relief valves interposed in oil paths to respective stage clutches in valve opening positions of the relief valves. CONSTITUTION:Oil pressure in an oil supply path 200 is transmitted through throttle flow paths 311-341 of corresponding relief valves 211-241 to clutches C1-C4 already operated in changing over the clutches. When the next stage clutch is operated by electromagnetic valves 114-144 and clutch change-over valves 113-143 in speed change, even if total pressure in the corresponding relief valves 211-241 is lower than the set pressure in the relief valve of previous stage clutch to close said relief valve, only leak flow from the throttle flow paths 311-341 flows to the clutch side so that no slip takes place in the clutch. Thus, the relief valve having a satisfactory overriding property is used while the clutch can be prevented from slips and damages.</p> |
