| 摘要 |
An electrical cable (20) is wrapped on and can be unwound from a reel (34) rotatable in unison with a brake drum (33) on a support (13,27). A clock spring (32) on the support (13,27) constantly urges the reel (34) to rewind the cable (20). A brake cord (36) fixed to the support (13,27) is wrapped in the rewind direction around the drum (33) and connected via a train of chain links (A,B,c) to a spring (41) that tensions the cord (36) to act as a frictional one way clutch against the drum (33) to hinder rewinding in any selected unwound position of the cable (20). To release clutch action, a further train of chain links (C,D,E) is interposed between the spring (41) and a control connection (45), by pulling of which the tension of spring (41) can be relieved to allow rewinding. A still further train of chain links (A,F,G) is connected to the cord (36) and to spring and buffer (53,55,21,60), adapted to re-tension the cord (36) momentarily for braking action in response to the cable (20) reaching fully rewound position defined by an abutment (61) on the cable (20) actuating the spring and buffer. |
