| 摘要 |
PURPOSE:To soften a speed change shock in all ranges by disposing variable throttle means for varying the degree of throttle according to a throttle valve opening in the middle of an oil path connecting an oil pressure source and at least either of low-speed and high-speed frictional engagement elements. CONSTITUTION:Pressurized oil discharged from a hydraulic pump P is conducted to a throttle valve Vt and a shift valve Vs through a manual valve Vm which can be switched to a neutral position, a drive position and a backward position, and engagement of low-speed and high-speed clutches CL, CH is controlled by the shift valve Vs. In a speed change control device, variable throttle means 22 for varying the degree of throttle according to throttle pressure Pt from a throttle valve Vt interlocking with a throttle valve opening, that is, a throttle pedal 8 is disposed between both valves Vm and Vs. The variable throttle means 22 comprises two fixed throttles 23, 24 and a switch valve 25 for switching the conncetion of the fixed throttles 23, 24, and the switch valve 25 is controlled by throttle pressure Pt. |
