| 摘要 |
<p>1. A speed change control for a motor vehicle, comprising a first control member for the passage of increasing speed ratios and a second control member for the passage of decreasing speed ratios, a fluid pressure actuated motor (20) for actuating the clutch, and a control mechanism (40) of the gear box, including means (42, 44) responsive to a pressure fluid for passing increasing speed ratios and for passing decreasing speed ratios, characterized in that it comprises, in combination, a three-way-valve (10) allowing to connect the active chamber (22) of said clutch motor (20) either to a pressure fluid source or to a reservoir, depending on whether it has been excited or not, a four-way-valve (30) associated to said means (42, 44) responsive to a fluid pressure, said means being comprised of a pair of independent fluid motors (42, 44), the four-way-valve (30) allowing either to connect, according to the actuated member, one of said fluid motors (42, 44) to the fluid pressure source via the active chamber (22) of the clutch motor (20) and the other fluid motor (42, 44) to the reservoir, or to connect both fluid motors (42, 44) to the reservoir if no control member has been actuated, both of said valves (10, 30) being excited simultaneously by the one or other of said control members and being automatically de-excited by control means responsive to termination of passing the desired speed ratio, and the connection via the active chamber (22) of the clutch motor (20) being established only above a predetermined value of the stroke of its piston (21) corresponding to a complete clutch operation.</p> |
