Invalid chair which can negotiate steps - has ratchet wheel and brake enabling two or four wheeled movement

摘要

The invalid chair or stretcher running gear consists of an axle with four equal arms. The free end of each arm carries a running wheel. The axle arms are joined to a brake wheel whose periphery is formed as a ratchet wheel. The brake is a wrap round belt tightened by a lever which has a fixed pawl to engage with the ratchet wheel. The lever is connected by a pull rope to a hand lever mounted on the invalid chair guide arm. The ratchet wheel teeth are profiled to permit a rotation in reverse only. The pawl can be moved out of the locking position to enable the axle arm to run normally on two wheels.