| 摘要 |
A ratchet-type tensioning mechanism (10) for a rope or cord (15) has a rotatable sheave (14) with faces having radially extending serrations. A releasable ratchet mechanism (21) permits rotation of the sheave (14) in one direction but not the other. A plurality of serrations having alternating ridges (17) and valleys (19) circumscribes the sheave (14), each of which has a radially extending portion extending outwardly from the base of the sheave (14), the outer end (34) of each of the ridges (17) being angled in the direction in which the sheave (14) rotates when the ratchet mechanism (21) is engaged, the ridges (17) being positioned at regular intervals around the circumference of the sheave (14) and being located so that a ridge (17) on one base of the sheave (14) faces a valley (19) on the opposite face of the sheave (14). Preferably the ridges (17) and valleys (19) have rounded edges whereby a rope (15) thereon does not become frayed. The device may include a ratcheting lever arm (54) which engages the wheel (58) and affords leveraged tensioning the rope (15). |
