| 摘要 |
The roll-back blocking device has a brake element which acts against the tyre (2) or the wheel rim of one of the wheelchair wheels, provided by a profiled roller which is mounted coaxially on a freewheel sleeve for free rotation in a forwards direction, supported between opposing frame arms (8,9) of a U-shaped carrier (7), pivoted to a knee-lever brake (14) and biased by a tension spring (13). |
