| 摘要 |
A transmission controller in a multi-ratio tractor transmission comprises a control dial 40 which is rotatable in one direction from a central position 43 into a working zone 42 in which speed matching for field work is selected and when rotated in second direction into a road working zone 44 speed matching for road use is selected. The tractor overall transmission comprises an epicyclic transmission (11, fig 1) that provides six ratios and a synchromesh gearbox (12) which provides four range ratios. When the control dial 40 is in one of the respective speed matching zones 42, 44 and a range change occurs in the synchromesh gearbox (12) the ratio in the epicyclic transmission (11) is also adjusted to ensure that the ratio provided by the overall transmission is the next overall ratio in the transmission. If the dial 40 is rotated into zones 47, 48 the transmission operates as an automatic transmission, but speed changes between engine speeds of 1600-2200 rpm can still be selected by a driver. |
