| 摘要 |
A gearbox for small gears comprises a switch for reversing the direction of rotation of an engine. The shaft of the engine imparts a rotary motion to a gear drive shaft which, in one direction of rotation, imparts a rotary motion in the same direction to a gear drive shaft through a first gear stage and, in the opposite direction of rotation, imparts a rotary motion in the same direction to the said gear drive shaft through a second gear stage. To avoid abrupt changes of speed an to ensure continuous regulation, the speed of the engine (1) can be changed by a double-layer variable resistance (8) which can be adjusted by a sliding contact (7) coupled to the switch (5) for reversing the direction of rotation. In the first switching position of the switch (5) for reversing the direction of rotation, the sliding contact (7) contacts the first layer (8') of the resistance and in the other switching position it contacts the other layer (8''). The switching operations of the switch (5) for reversing the direction of rotation are carried out in the intermediate position between the two layers (8' 8''). |
