| 摘要 |
PCT No. PCT/AU94/00346 Sec. 371 Date Mar. 11, 1996 Sec. 102(e) Date Mar. 11, 1996 PCT Filed Jun. 24, 1994 PCT Pub. No. WO95/00775 PCT Pub. Date Jan. 5, 1995A variable ratio power transmission in the form of a gear box is described, in which the gear ratio of the input and output shafts can be varied continuously between a maximum and a minimum. The power transmission comprises a first bevel wheel (40) rotatably mounted in connection with a U-shaped member (32) on a first axis (34). The U-shaped member (32) is pivotable about the axis (34) and is coupled to the bevel wheel (44) via a sprag clutch (36). Hence, pivoting movement of the U-shaped member (32) in a first direction about the axis (34) results in a torque being applied via the sprag clutch (36) to the bevel wheel (44), whereas pivoting movements of the U-shaped member (32) in the opposite direction has no effect via the sprag clutch (36) on rotation of the bevel wheel (44). A second bevel wheel (50) is also coupled to the U-shaped member (32) via a second sprag clutch (38) which operates in the reverse direction to that of the first sprag clutch (36). An actuating member (52) is mechanically coupled to the U-shaped member (32) via a rotational coupling (63). Rotation of actuating member (52) about a second axis (60) produces an orbital motion of the rotational coupling (63) which in turn produces an oscillating pivoting movement of the U-shaped member (32) about the first axis (34). By varying the radius of orbit of the rotational coupling (63) the angle through which the U-shaped member (32) pivots can be varied, so that an output torque transmitted via the bevel wheels (44, 50) can be varied independently of an input torque applied to the actuating member (52).
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