摘要 |
A gearbox includes two coaxial primary shafts, a secondary shaft and a lay shaft. The two primary shafts carry fixed gearwheels acting as driving gearwheels of the gear trains associated with the forward gears and with the reverse gear. The secondary shaft carries idle gearwheels acting as driven or intermediate gearwheels of the gear trains associated with the forward gears and with the reverse gear, and a final reduction pinion. The lay shaft carries a first idle gearwheel acting as driven gearwheel of a first gear train associated with the reverse gear, a second idle gearwheel acting as driven gearwheel of a second gear train associated with one of the forward gears, and a fixed gearwheel acting as parking gearwheel. The lay shaft is permanently kinematically connected to the secondary shaft via a third gear train having a first fixed gearwheel carried by the lay shaft, a second idle gearwheel coaxial with the two primary shafts and a third fixed gearwheel carried by the secondary shaft, the two fixed gearwheels of the third gear train meshing permanently both with the idle gearwheel of the third gear train.
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