Variable Speed Winch

This invention relates to winches, and more particularly to variable speed winches of the kind used to manipulate the sheets of sails or the like.

It is known to construct marine winches having variable rotation speeds, and in which a reduction gear is located so that a handle turned in a clockwise sense gives a high speed to a drum in an anti-clockwise sense, whereas an opposite handle rotation gives said drum a low speed in a clockwise sense. It is an object of the present invention, however, to provide a winch in which a plurality of speeds may be selected for a drum, the rotation of which is unidirectional, but in which said handle may rotate in either sense. It is a further object to provide a drum which is freely manually rotatable by an operator who meanwhile maintains said handle stationary.

According to the invention therefore, in one of its aspects, a winch comprises, in combination, a uni-directional drum rotatable initially by the clockwise motion of a handle in a clockwise sense only, and a gear selector comprising a control plate rotatable with respect to said drum into an extreme clockwise position wherein a first gear ratio is selected, whereby subsequent clockwise rotation of said handle gives the drum a clockwise speed equal to that of the handle, and wherein subsequent anti-clockwise rotation of said handle causes said drum to continue clockwise rotation at an intermediate higher speed with reference to the handle, up to a point where said control plate is urged into an extreme anti-clockwise position with respect to said drum to select a second gear ratio, whereupon the reversal of the handle and subsequent clockwise rotation thereof causes continued clockwise rotation of said drum at a still higher speed with reference to said handle, and wherein reversal of said handle and subsequent further anti-clockwise rotation thereof causes said drum to revert to said intermediate higher speed whilst continuing to rotate clockwise.

One embodiment of the invention defined in the preceding paragraph will now be described herein with reference to the accompanying drawings, in which similar references indicate corresponding parts, and in which

FIG. 1 shows, in perspective, a view of an assembled winch with its operating handle detached,

FIG. 2 shows said winch in elevation and partly in section,

FIG. 3 shows, in plan and partly in section, a view along the line 3--3 of FIG. 2,

FIG. 4 shows, in perspective, an exploded view of the speed-changing mechanism of said winch,

FIG. 5 shows, in elevation and partly in section, a detailed view of the location of a control plate for said winch, and

FIG. 6 shows said control plate in plan view from above.

Upon referring to the drawings it will be seen that a drum 7 is mounted for rotation with respect to a base support 8 about a shaft 9 by means of the handle 10 when said handle removably engages said shaft by means of the co-acting splines 11 and 12. Rotary motion of the shaft 9 is transmitted to the drum 7 via a reduction gear train which includes the pinions 13 and 14 and the ring gear 15 in a manner hereinafter described.

When said "first" gear is engaged by the clockwise movement of the control plate 16, said plate takes up the position shown in FIG. 1 with the studs 17 and 18 hard up against the ends of their respective slots 19 and 20. The drum 7 may then be rotated in a clockwise sense by hand whilst the handle 10 is held stationary, thus permitting an operator to bring in the slack on a sheet without disengaging first gear. This action is desirable, for example, when a considerable length of sheet connects a sail with the drum. When the slack is taken up, the operator may then commence to turn the handle 10 normally in a clockwise sense, thus achieving the highest available drum speed but with the minimum mechanical advantage. As the load on the sheet increases, the operator reverses the handle direction until the highest available speed ratio of handle and drum provides the lowest drum speed but the greatest mechanical advantage. If at any time an intermediate condition is required the operator may quickly move the handle clockwise to take advantage of the intermediate speed ratio available.

To achieve the above-described results, the control plate 16 effects a change from "first" to "second" gear owing to the action of a ratchet ring 21 which is held against rotation with respect to the shaft 9 by the co-acting splines 22 and 23, thus connecting the handle 10 to said reduction gear train. When in first gear with the control plate 16 turned fully clockwise, the clockwise rotation of the handle 10 and hence of the ring 21 causes engagement between the ring and one or more pawls such as 24 and 25 located hingedly with respect to the drum. However, anti-clockwise rotation of said handle causes said ring to move freely past said pawls. The control plate, which is attached to an end cheek of the drum via the studs 17 and 18, is so shaped that the pair of arcuate slots 19 and 20 have respective depressions 26 and 27 which accept and hold said studs in the anti-clockwise or second gear position shown in FIG. 6. Said slots however cause each said stud or a shoulder thereon to ride up upon the respective shelves 28 and 29 within said slots 19 and 20 when said plate is rotated into the extreme clockwise position. In both said positions the control plate is urged outwardly away from the end cheek under the influence of axially directed spring-loaded pins 30 and 31. Thus during said anti-clockwise movement of the handle the ratchet ring 21, upon the lower surface of which a pair of cams 32 and 33 is formed, rides axially outwardly under the influence of a lower cam plate 34 when moving from the second gear position to the first gear position. As each stud 17 and 18 moves up upon its respective associated shelf 28 and 29 the control plate 16 is depressed against the pins 30 and 31 and so puts a series of recesses such as 35 located on the reverse side of said control plate into a position wherein its engagement by a set of upwardly directed ball-bearings such as 36 mounted captively upon the top of the ratchet ring 21 is possible. This possibility is not significant when the handle 10 is moved clockwise, but when it is moved anti-clockwise the top cams 32 and 33 upon the ratchet ring 21 ride up over the co-acting lower cams 37 and 38 upon the lower cam plate 34 at certain angular positions of said handle at which said ball-bearings engage the control plate via said recesses, and hence cause said control plate to move anti-clockwise to a position where the ball-bearings can no longer engage said recesses.

Throughout said cam action the spline 23 on the shaft 9 allows the ratchet ring 21 to ride to and fro in an axial direction. It will be seen that the pins 30 and 31 urge the control plate 16 away from the drum 7 when the second gear position is assumed and hence it is necessary to push the control plate manually or otherwise towards the drum before twisting it into the first gear position.

A retaining ring or nut 39 is mounted below the lower cam plate 34 to align the shaft 9 and the relatively moving components thereon with respect to the base support 8 of the winch.

In one embodiment of the invention said reduction gear train is so designed that said intermediate higher speed ratio of drum to handle is 3:1, and said still higher speed ratio is 6:1.

If the above-described cam action had been bi-directional as in some prior systems, it would be possible to rotate the drum 7, during tailing, so energetically that the control plate 16 would flick out of first gear into the second gear position. Tailing is desirable when an operator is manipulating a large sail such as a spinnaker, which must be allowed to extend an attached sheet if necessary, said sheet then being reeled in again at the first opportunity by means of the winch, which preferably should not be allowed to disengage its first gear unless the operator so decides.

To permit tailing without risk of such an unwanted gear change said cam action has therefore been made uni-directional. It is for this reason that upon the lower surface of the ratchet ring 21 and upon the upper surface of the lower cam plate 34 a respective pair of cams 32, 33 and 37, 38 in the shape of tapered ramps is formed, each having a squared-off shoulder remote from its faired-in end as best shown in FIG. 4. These ramps cause the ratchet ring 21 to move out axially at pre-set angular relative displacements of the ratchet ring 21 with respect to the lower cam plate 34. However, when the control plate 16 is in the fully clockwise or first gear position, the clockwise turning of the handle 10 causes a coacting pair of said squared-off shoulders on the ratchet ring to engage the similar shoulders on the lower cam plate. The ratchet ring, which turns with the shaft 9 because it is splined thereto, thus causes the lower cam plate also to turn with the shaft. Hence there is no axial movement of the ratchet ring outwardly to cause engagement of the control plate by the ball-bearing 35 even when the drum 7 is then turned so as to free-wheel rapidly in a clockwise sense without moving the handle 10.

It will be appreciated that apparatus may be constructed in accordance with the invention using other speed ratios, and that the ratios above described are given by way of example only. Furthermore, the references herein to clockwise and anti-clockwise rotation may be interchanged, mutatis mutandis.