| 摘要 |
PROBLEM TO BE SOLVED: To prevent such a state that the vehicle starts at a high speed side gear ratio by holding a trunnion in its neutral position even if there is a wheel rotation in any direction during engine stoppage. SOLUTION: When a wheel is rotated by coasting or the like during engine stoppage, an output rotation driven pump 22 is driven by the wheel and an oil pressure is generated in a circuit 32. The pressure reaches shift control valves 37 and 38 and it heads for a piston 13 via a forward/reverse change-over valve under control of the shift control valves. When the wheel rotates forward by coasting or the like and the trunnion 12 is offset as indicated by an arrowδ, a forward precession cam displaces a right end of a lever 39 downward as indicated by an arrowγ, and the trunnion 12 is returned in an opposite direction via the piston 13 by a differential pressure generated by a same direction stroke of a spool 37a. When a gear ratio returns to a command gear ratio commanded to a left end of the lever 39, the spool 37a returns to a neutral position closing both side chambers of the piston 13 and no strokes of the trunnion 12 occur in any direction. |
