| 摘要 |
<p>The system comprises an internal body (4) fixed to the wheel hub and an external body (9) fixed to the transmission gears by a chain (3). The two coaxial bodies are joined by a roller bearing and free to rotate relative to each other. An intermediate cylindrical body (5), housed between the internal and external bodies, having slots (10) in which are housed radially movable locking parts (7). This intermediate body has a ratchet (6) allowing its rotation relative to the external body in a single direction only. The external body has in its internal surface several grooves having a complementary shape and section with the locking parts. The internal body has means for radially pushing the locking parts towards the grooves when the intermediate body rotation relative to the external body is locked.</p> |
