| 摘要 |
A check valve is installed in a hydraulic line for hydraulic oil to be fed to a forward movement hydraulic clutch, while an accumulator for accumulating some amount of the hydraulic oil fed to the hydraulic clutch is installed between the check valve and the hydraulic clutch. Further installed is a control spool that is operated by the hydraulic oil fed to the forward movement hydraulic clutch and that cooperates with the check valve to hold the hydraulic oil accumulated in the accumulator. According to this arrangement, even if the oil pressure drops momentarily due to a speed gear shift, the pressure for the hydraulic clutch before the gear shift is held by the hydraulic oil accumulated in the accumulator. Thus, a delay in torque restoration due to a slip of the hydraulic clutch can be eliminated, so that an operator can be freed from having a feeling of torque loss or a shock, and a feeling of uneasiness such as a feeling of reversing on an uphill slope, during the gear shift.
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