| 摘要 |
A tractor transmission comprises a main transmission 11, an auxiliary transmission 15 and a high/low speed change mechanism 14 that are arranged in series and have shift sleeves S1-S5, operated by hydraulic cylinders C1-C5 controlled by a programable controller (32, fig 4), which change gear ratios/ranges from, for example, high speed Hi to low speed Lo and vice versa. When the transmission 11, the auxiliary transmission 15 and the speed change mechanism 14 are all set in their highest ratios/ranges the controller (32, fig 4) prevents, via a program, the speed change mechanism 14 switching from the high speed range Hi to the low speed range Lo. A single shift lever (30, figs 4 to 7) provides control signals to the controller (32) which selects, via valves (V1-V6), appropriate shift sleeves S1-S5 to operate in the transmissions 11, 15 and the speed change mechanism 14 so that the desired transmission ratios/ranges are selected for operating the tractor. Shift lever 22 controls a backward/ forward drive mechanism 13 while creep shift lever 29 operates a super-reduction mechanism 16. |
