Variable speed winch

Abstract

A variable speed winch including a uni-directional drum rotatable initially by the clockwise motion of a handle in a clockwise sense only. The winch also includes a gear selector including a control plate rotatable with respect to the drum into an extreme clockwise position wherein a first gear ratio is selected. The gear selector further includes ratchet structure, splined to a shaft rotatable by the handle. The ratchet structure is slidable axially with respect to the shaft under the influence of a cam structure responsive to the relative angular displacements of the handle with respect to the control plate. The control plate has recesses engageable by respective spring-loaded balls captively supported by the ratchet structure. The balls are adapted to enter and lock within the recesses in response to an anti-clockwise rotation of the handle sufficient to cause axial sliding of the ratchet structure, with respect to the shaft, under the influence of the cam structure. Subsequent clockwise rotation of the handle gives the drum a clockwise speed equal to that of the handle, and subsequent anti-clockwise rotation of the handle causes the drum to continue clockwise rotation at an intermediate higher speed with reference to the handle, up to a point where the control plate is urged into an extreme anti-clockwise position with respect to the drum to select a second gear ratio, whereupon the reversal of the handle and subsequent clockwise rotation thereof causes continued clockwise rotation of the drum at a still higher speed with reference to the handle, and reversal of the handle and subsequent further anti-clockwise rotation thereof causes the drum to revert to the intermediate higher speed while continuing to rotate clockwise.

The claims defining the invention are as follows: 
     
       1. A winch comprising, in combination, a unidirectional drum rotatable .Iadd.in one sense of rotation only .Iaddend.initially by the .[.clockwise motion.]. .Iadd.rotation .Iaddend.of a handle in a .[.clockwise.]. .Iadd.first .Iaddend.sense .[.only.]., and a gear selector comprising a control .[.plate.]. .Iadd.member .Iaddend.rotatable with respect to said drum into .[.an extreme clockwise.]. .Iadd.a first .Iaddend.position wherein a first gear ratio is selected.[., whereby subsequent clockwise.]. .Iadd.in which .Iaddend.rotation of said handle .Iadd.in said first sense .Iaddend.gives the drum a .[.clockwise.]. .Iadd.rotational .Iaddend.speed equal to that of the handle, and wherein subsequent .[.anti-clockwise.]. rotation of said handle .Iadd.in a second sense opposite to said first sense .Iaddend.causes said drum to continue .[.clockwise.]. rotation .[.at.].  .Iadd.in said one sense via .Iaddend.an intermediate .[.higher speed with reference to the handle, up to a point where said.]. .Iadd.gear ratio selected by this reversal of the sense of rotation of the handle to obtain rotation of the handle in said second sense, said rotation of the handle in the second sense enabling said .Iaddend.control .[.plate is.]. .Iadd.member to be .Iaddend.urged into .[.an extreme anti-clockwise.]. .Iadd.a second .Iaddend.position with respect to said drum to select a second gear ratio .Iadd.for rotation of said handle in the first sense, .Iaddend.whereupon .Iadd.after selection of said second gear ratio .Iaddend.the reversal of the handle .[.and.]. .Iadd.with .Iaddend.subsequent .[.clockwise.]. rotation thereof .Iadd.in said first sense .Iaddend.causes continued .[.clockwise.]. rotation of said drum .[.at a still higher speed with reference to said handle.]. .Iadd.in said one sense via said second gear ratio .Iaddend.and wherein .Iadd.a subsequent .Iaddend.reversal of said handle .[.and subsequent.]. .Iadd.with .Iaddend.further .[.anti-clockwise.]. rotation .[.thereof.]. .Iadd.in said second sense .Iaddend.causes said drum to revert to .Iadd.rotation via .Iaddend.said intermediate .[.higher speed.]. .Iadd.gear ratio .Iaddend.whilst continuing to rotate .[.clockwise.]. .Iadd.in said one sense.Iaddend., said gear selector further comprises ratchet means .[.splined to a shaft rotatable by said handle,.]. whereby .[.clockwise motion.]. .Iadd.rotation .Iaddend.of said handle .[.operates a gear train.]. .Iadd.in said first sense directly drives said drum .Iaddend.in said first gear ratio.Iadd., .Iaddend.via said shaft but whereby .[.anti-clockwise motion.]. .Iadd.rotation .Iaddend.of said handle .[.operates said gear train.]. .Iadd.in said second sense drives said drum .Iaddend.in said .[.second.]. .Iadd.intermediate .Iaddend.gear ratio via .[.said shaft.].  .Iadd.a gear train; .Iaddend. said ratchet means being slidable .[.axially.]. with respect to said shaft under the influence of cam means responsive to .[.the relative angular displacement.]. .Iadd.rotation .Iaddend.of said handle .[.with respect to said control plate.]. .Iadd.in said second sense.Iaddend.,   said control .[.plate.]. .Iadd.member .Iaddend.has .[.recesses.]. .Iadd.first entrainment means .Iaddend.engageable by .[.respective spring loaded balls captively.]. .Iadd.second entrainment means .Iaddend.supported by .[.said.]. ratchet means, .[.and said balls are.]. .Iadd.one of said first and second entrainment means is .Iaddend.adapted to .[.enter and lock within said recesses.]. .Iadd.entrain the other of said first and second entrainment means .Iaddend.in response to .[.an anti-clockwise.]. rotation of said handle .Iadd.in said second sense .Iaddend.sufficient to cause .[.axial.]. sliding of said ratchet means.[.,.]. with respect to said shaft.[.,.]. under the influence of said cam means whereby said control .[.plate.]. .Iadd.member .Iaddend.is urged .[.anti-clockwise until.]. .Iadd.towards said second position in which .Iaddend.said gear train assumes said second gear ratio.   
     
     
       2. A winch as claimed in claim 1, wherein said control plate is normally continuously urged axially outwards .[.away from said drum by spring-loading means.]. .Iadd.relative to said shaft.Iaddend.. 
     
     
       3. A winch as claimed in claim 2, wherein said control .[.plate.]. .Iadd.member .Iaddend.is adapted for .[.manual clockwise.]. rotation towards said .[.second.]. .Iadd.first .Iaddend.gear position after initial inward axial displacement of said control .[.plate.]. .Iadd.member .Iaddend.with respect to a plurality of reference studs fixed with respect to support means .[.for.]. .Iadd.on .Iaddend.said drum, said studs .[.being thereby adapted to emerge.]. .Iadd.by this displacement moving .Iaddend.from a rest position within respective co-acting arcuate slots perforating said control .[.plate into.]. .Iadd.member to .Iaddend.a position wherein said studs ride up upon and slide with respect to shoulders extending throughout at least part of each said slot. 
     
     
       4. A winch as claimed in .[.any one of.]. claim 1, wherein said cam means comprises one or more uni-directional tapered ramps disposed upon a disc mounted co-axially with respect to said shaft, one end of each said ramp being faired in to said disc, and the other end of each said ramp comprising a squared-off shoulder directed axially away from said disc, and each said ramp being adapted to engage a co-acting ramp disposed upon said ratchet means on a surface of said ratchet means remote from said control .[.plate.]. .Iadd.member.Iaddend., whereby axial movement of said ratchet means outwardly to cause engagement of said control .[.plate.]. .Iadd.member .Iaddend.is prevented during free-wheeling of said .[.drum.]. .Iadd.ratchet means .Iaddend.with respect to said shaft .[.via said ratchet means.]. after said control .[.plate.]. .Iadd.member .Iaddend.has been turned .[.fully clockwise into.]. .Iadd.to said first position to select .Iaddend.said first gear .[.position.]. by .[.clockwise turning.]. .Iadd.rotation .Iaddend.of said handle .Iadd.in said first sense.Iaddend..