| 摘要 |
A powershift transmission 18, eg for a tractor, is operated by a set of clutches actuated by solenoid valves 22 controlled by a vehicle control unit 32 so as to change a gear ratio in the transmission 18. The control unit 32 responds to a load signal, representing an engine load, which is automatically and repeatedly adjusted during a shift in the transmission 18 as a function of an operational status of an auxiliary device, such as a PTO shaft 24 or a hitch etc. The PTO shaft 24 is driven via a clutch by the engine which also drives a pump 28 that supplies hydraulic fluid to the control valves 22. Control unit 32 receives signals form various switches, eg PTO shaft switch 36, control valve switch 38, and uses these signals as an input to an algorithm (see figs 2, 3 and 4) that modifies the load signal as a function of speed ratio. |
