| 摘要 |
<p>Shifting mechanism is provided for shifting gears in a gear box. The gear box has a housing, a gear shaft in the housing, a plurality of gears on the shaft, a shift key movable along the shaft for individually connecting the gears to the shaft, a shift collar positioned around the shaft and engaged with the shift key, and a shift fork for moving the collar along the shaft. The shift key moves along a longitudinal groove in the shaft and has a lug with an engaged or extended position extending radially outwardly from the groove and the shaft and a disengaged or retracted position in which the lug does not extend out of the groove. The gears have bores through which the gear shaft extends so that the gears are rotatably supported on the shaft. At least one of the gears has a plurality of uniformly spaced recesses or notches circumferentially located around the bore to receive the lug of the shift key so that the gear rotates with the shaft. The recesses have ramps extending angularly in common directions from the bottoms of the recesses toward a common face of the gear. The ramps force the shift key lug toward the retracted position when the key moves from one gear to another to prevent two gears from being engaged at the same time. A neutral collar is rotatably supported in the gear shaft and receives the shift key lug when the gear box is in a neutral position. The neutral collar has two oppositely-facing ramps to force the lug toward the retracted position when the shift key is moved in either direction from neutral.</p> |
