| 摘要 |
PURPOSE:To suppress an engine from blow up when a speed change is performed, by controlling a clutch so as to operate in slip condition not completely releasing the clutch from engagement but weakening the engaging force and reducing a speed change shock in a clutch operative region when an auxiliary transmission performs a speed change in the operative region. CONSTITUTION:Since a clutch 22 operates in a directly coupled condition or in a condition approximate to the directly coupled condition in regions A and C, if speed change of an auxiliary transmission 1 is performed in these regions, a function of absorbing a speed change shock is eliminated in the clutch 22 by slip. Thereupon, at the time of speed change in the regions A, C, the clutch 22 is actuated in slip condition by outputting an instruction of closing the fourth atmosphere opening valve similarly to a region B. A speed change of 3-speed 4-speed is performed in the region A, and if the clutch 22 is released from operation by outputting an instruction of closing the third atmosphere opening valve in the time of the speed change, an engine, despite of speed decrease after the speed change in case of this shiftup speed change, generates a blow up of the engine speed in the initial time of the speed change by releasing the clutch from its operation. Here if the clutch is operated in slip condition at the time of the speed change, it suppresses the blow up.
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