| 摘要 |
A gearbox with a large number of ratios for agricultural tractors and the like, including first and second reduction stages (10, 11) with gears defining a plurality of forward and reverse gear ratios, which are engageable by means of first and second hydraulic friction clutch units (12, 13) whose engagement and disengagement is effected in a combinable manner by means of a hydraulic distributor (14) and respective valve units. These valve units include electro-hydraulic proportional-response valves (21-16) piloted by an electronic control unit (27) connected to means (36-40) for monitoring the operative conditions of the tractor, so as to adjust the combined engagement and disengagement of the hydraulic clutches to the operative conditions of the tractor. |
