| 摘要 |
A wheel (10) of a traction device for towed vehicles is driven manually by a lever arm (18) through a pawl and ratchet drive mechanism (40b). The lever arm can be manually oscillated about the horizontal axis of the wheel. The ratchet (48), can be set by means of a control arm (45) acting by means of a spring loaded plunger (46) on a curved touch face (47) of the ratchet so as to communicate drive to the wheel in either direction of rotation. A non-return ratchet (56) similar to the drive ratchet (48) may also be set by a control arm (52) similar to control arm (45) to inhibit back-rotation of the wheel.
<??>The lever arm may also be used to steer the wheel by rotating it about an intersecting vertical axis (4).
<??>By choosing an appropriate effective lever length the user can regulate his effective mechanical advantage: where two or more wheels are provided, separate drivers will be provided from a single lever arm thus doing away with the need for a differential mechanism. |
