GB2061862A - Winch drive - Google Patents

Abstract

A manually powered multi- speed winch has a drive between a shaft and the drum (11) which is automatically disengaged upon drive reversal. The winch can be set to a first drive ratio, of least mechanical advantage, by a control knob (85) accessible at the outside of the winch. The knob is lockable to override the automatic disengagement. Locking is by engagement between a pin (86) and the transverse extension (90) of an L- slot in the stem (80) of the knob (85). A stirrup (71) is thereby held downward and an axially movable drive member (35) upward to maintain unidirectional drivable connection between the shaft and itself, through pawl and ratchet arrangement (60, 63). With the knob thus locked first reversal engages a second drive ratio and second reversal returns the winch to the first drive ratio. <IMAGE>

Description

SPECIFICATION Winch This invention relate to winches of the manually powered type.

Such winches have for some time been provided with a plurality of drive ratios between their drive input and the winch drum and various arrangements have been proposed for allowing interchange between various drive ratios, this interchange being achieved, at least in all the more recent developments, automatically upon reversal of the direction of the drive input, without further manual interference.

There are two sorts of winch to which this interchange is applied.

In a first sort the first speed ratio, the ratio of lowest mechanical advantage to the user, is a 1:1 drive achieved by direct action between a handle and the drum (U.S. Patent 3728914) or through a pawl and ratchet drive one side of which is associated with the drum and the other side of which is associated with the drive shaft (for example, U.K.

Patent 1486777).

In a second sort, all the speed ratios involve drive transmission through gear trains. In one line of development illustrated by U.S. Patent 3145974 and 4054266 automatic change is provided by means of a movably-mounted traveller gear which is engageable between coplanar transmission pin ions while they are rotating in one direction but is driven in an orbital motion out of engagement by their rotation in the opposite direction. The proposals seen in U.K. Patents 1400393 and 1499814, on the other hand, use axial movements to engage and automatically disengage drive. In 1400393 drive coupling to one gear is through a dog clutch which is manually urged into engagement but is positively driven out of engagement by face cams moving it axially when drive is reversed.In 1499814, for a special application, a collar is axially movable to interfere with the driving engagement between pawls on a pinion and a ratchet track on the drive shaft, the pinion and ratchet track being both axially stationary.

An object of the present invention is to provide an improved automatically ratiochanging winch of either of the sorts outlined above, in which a selector is operated to cause the engagement of a given one of a plurality of drive rations between the input and the drum, and wherein disengagement of that give ratio is automatic upon reversal of the direction of drive input, which reversal involves engagement of a second ratio. When there is a second reversal of drive input then normally, the first speed having been disengaged, a third speed will be engaged. These speeds are of progressively increasing mechanical advantage as between the input and the drum. Sometimes the user may wish not to traverse all the speeds upon successive reversals, and may wish to remain in the first two speeds.

To permit this, according to the present invention the selector means includes a lock whereby by a manual operation a movable member may be retained in a condition in which it causes drive engagement of the first speed despite reversal of direction of drive input.

The movable member is preferably an axially movable drive transmitting member, its drive-transmitting condition being assured by unidirectional drive means associated with it so long as drive continues to be transmitted therethrough between the member and the shaft.

Preferably the selector means includes a stirrup engaging a groove on the member and which is pivotally mounted to a frame of the winch, actuation of pivotal movement of the stirrup being by means of a push button accessible to the exterior of the winch.

In one preferred embodiment the member is a pinion forming part of a first gear drive train, being permanently enmeshed with a next pinion in that train in any axial position; in another preferred embodiment the member is a coupling sleeve permanently enmeshed with a second shaft coaxial with the said first shaft, to transmit drive between the shafts in a 1:1 ratio.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings wherein: Figure 1 is a diametrical section embodiment of which, Figures la and ib are scrap sections from Fig. 1 but showing two other conditions of the movable pinion and unidirectional drive, Figure 2 is a radial section to show an intermediate stage of the gear train, Figure 3a and b are side and plan views respectively of a selector fork, Figure 4 is a side view of a movable pinion, Figure 5 is a partial diametrical section through a second embodiment, Figure 6 is a side view of part of the said embodiment, Figure 7 is a top view of part of the embodiment on the arrow VII of Fig. 5 and Figure 8 is a side view partially cut away of another portion of the embodiment.

The winch as seen in Fig. 1 is for manual operation and has a central drive shaft 1 which at its middle portion is supported by a rolling contact bearing 2 within a cylindrical sleeve 3. The cylindrical sleeve forms an extension of a flange plate 4 which, together with a base 5 to which it is secured at the top of the latter, forms a stationary framework for the winch. At its uppermost end the sleeve 3 is splined to extension sleeve 6 and these two are axially keyed together by key 7. The extension sleeve 6 forms a centralising bearing for the drive shaft 1. Basepiate 5 is fast with a raised central portion 5' which offers a support for gearing on an extension head of the main drive shaft 1 and for intermediate gearing of the drive transmission trains as will be described more fully later.

Primarily however axial movement of the drive shaft 1 is prevented by keys 8 engaging a groove 9 in that shaft and entering through windows in extension sleeve 6, being held radially by a keeper ring 10 at the outer surface of the iatter.

The winch drum 11 has at the inner periphery of its lower edge an internal gear 1 2 and at its upper edge it is secured by three bolts 1 3 (only one being shown) to a lower jaw plate 14 of a self-tailing channel 19. In turn there is secured to the lower jaw 1 4 of the channel an upper jaw 1 5, by means of three bolts 1 6 (only one being shown).

Entrapped between the lower and the upper jaws 15,14 is a slip ring 1 7 which defines a cylindrical base surface 1 8 of self-tailing channel 1 9. At one position around the periphery of ring 1 7 a stripper tongue 20 projects and enters into a vertically extending, inwardly concave channel 21 at the back of the stationary line guide arm 22 which is integral with a top plate 23 which is splined at 24 to an uppermost part of the extension sleeve 6.The line guide has at its lower end an outwardly turned, inclined, line guide 25 which is to guide and assist the transition of line from the surface of the drum 11 into the self-tailing channel 1 9. A flanged washer 26 is interposed between the stationary top plate 23 and the rotating upper jaw 1 5, and the top cao 27 is secured by bolts 28 to the top plate and, by entrapping between itself and the top plate 23 a split collar 29 which is housed in a groove in the extension sleeve 6, assures axial positioning of itself and the top plate.

To permit rotation of the drum 11 and the jaws 14,15, rolling contact bearings 30 surround the outer circumference of the sleeve 3 and fit within inner sleeve 31 integral with the drum, and within an upper flange 32 of the drum.

Drive is transmittable between the central drive shaft 1 which has a facetted blind bore for the reception of a stub key from a drive handle, by means of any one of three geared drive transmission trains, all of different drive ratios and being successively engageable upon successive reversals of the direction of turning of the drive shaft so as to transmit between that shaft and the drum successively lower drive ratios i.e. successively higher mechanical advantages. A first and lowest mechanical advantage drive train is provided by pinion 35 which is axially movable upon the drive shaft, being borne on an extension head 36 of the shaft splined at 37 to the lower end of the main portion of the drive shaft 1 and of complex formation which will be described I water in more detail.

Pinion 35, in whatever axial position, meshes with pinion train 38 on an intermediate complex gear 39 mounted on intermediate shaft 40 as is seen in Fig. 2. Gear 39 includes another series of integral gear teeth 41 and also provides a support for a gear ring 42 which is engageable with complex gear 39 by unidirectional drive means in the shape of a pawl 43 on the gear 39 and ratchet teeth 44 upon the inner periphery of the ring 42.

Gear ring 42 meshes at all times with gear teeth 45 formed on the extension head 36.

Teeth 41 however mesh permanently with gear ring 46 which is rotatably borne on a second intermediate gear shaft 47, Fig. 1.

The teeth of gear ring 46 mesh permanently not only with teeth 41 on gear 39 but also with geared teeth of a gear ring 47 which is rotatably mounted to the extreme base of the extension head 36 and coupled to that head 36 through a unidirectional drive made up of pawls 48 in the head and ratchet teeth 49 on the inner periphery of the ring 47. These pawls are held in position in the housing and axial position of the ring 47 is assured by end cap 56 secured by screw 50 to the extreme end of the head 36.

The final element of all the gear drive trains is a transmission sleeve 51 mounted, through rolling contact bearings 52, on the second gear shaft 47 and which has at its uppermost end gear teeth 53 which permanently mesh with the internal gear teeth 1 2 on the drum.

Gear ring 46 is the sole source of drive input to the transmission sleeve 51 and is coupleable to that sleeve by means of unidirectional drive formed by pawls 54 in the gear ring 46 and ratchet teeth 55 formed at the lowermost end of the transmission sleeve 51.

The effect of the unidirectional drive 54, 55 is to uncouple from any part of the gear drive transmission trains beyond that drive the effect of any overrunning of the winch drum. It has the effect of making all the automatic transmissions which are about to be described entirely independent of overrunning by the drum and controlled only by those factors which are about to be described.

The first drive train that of highest drive transmission between the drive input shaft and the drum and therefore of lowest mechanical advantage is that formed by pinion 35, pinion 38, pinion 41, gear ring 46 and then, in common with all the other drives, transmission sleeve 51, gear teeth 53 and internal gear 12.

The second drive train, of intermediate mechanical advantage, includes ring 47 and gear ring 46.

The third train and that of greatest mechanical advantage includes teeth 45, ring 42, gear 41 and ring 46.

The successive trains have successively odd and even numbers of gears in them and also have successively oppositely opposed unidirectional drives in them (namely in the first train pawls 60 in pinion 35 with ratchet teeth 61 on drive shaft 1, in the second train pawls 43 with ratchet teeth 44 on gear ring 42 and in the third train pawls 48 with ratchet 49).

Thus successive rotation of the drive input shaft in opposite directions would cause transmission of drive successively through different drive ratios. However, if means are not found for disconnecting the first of these drives (that of lowest mechanical advantage) then it will always be preferentially engaged in a given direction of rotation of the main drive shaft, since it will cause a rotation of the gear ring 47 in the third train in a sense that it is overtaking the extension head 36 and is merely clicking past the ratchet teeth 49 on it.

Means are therefore provided for the automatic self-disengagement of the pinion 35 upon a first reversal of drive and these will be described in more detail now.

As has been mentioned the pinion 35 (Fig.

4) is axially movable on the drive shaft of which the head 36 forms part. Head 36 has a smooth cylindrical surface 65 upon which is rotatably borne a smooth cylindrical surface 66 of the pinion 35.

The pawls 60 are housed in pawl housings 67 at an uppermost part of the cylindrical surface 66 being held axially in position by a cover plate 64 (Fig. 1). Level with a lower portion of the cylindrical surface 66 and in the outer periphery of the pinion 35 there is formed a channel 68 which is continuous around that circumference and which is engaged by pins 69 directed inwardly from legs 70 of a fork 71 best seen in Fig. 3. The fork 71 is mounted upon a bracket 72 fixedly secured to the flange 4 and is pivoted to that bracket by a pin 73 passing through a bore 74 in the base of the fork. The fork has an actuating arm 75 extending at an angle to the legs 70, and this has a small aperture 76 for the reception of an end hook of a tension spring 77 of which the other end is anchored in the bracket 72.The effect of the pivotal mounting of the stirrup is that with pins 69 permanently engaged in channel 68 on the pinion 35 the pivoting can in principle cause axial movements of the pinion 35 along the drive shaft. An uppermost axial position is defined by abutment of the cover plate 64 against a washer 78 entrapped between ratchet teeth 61 and the bottom of the cylindrical sleeve 3, and a lower limit position of travel is defined by abutment of an undercut ledge 79 in the gear 35 with a flange 80 on the extension head 36. The effect of the tension spring 77 is to bias the stirrup towards clockwise rotation and hence to bias the pinion 35 towards its lower limiting position. The diameter of the cylindrical part 65 of the drive shaft head is substantially equal to the maximum diameter of the ratchet teeth 61.Thus, if the pawls 60 are clicking over the ratchet teeth 61 their innermost edges 62 will be at the same diameter as that of the cylindrical surface 65 and they will be free to transfer downwardly to the cylindrical surface 65. This condition is seen in Fig. 1 b, where the pinion 35 is free to move axially in the direction of the arrow A. That this movement will happen when the occasion arises is assisted by the biasing due to the spring 77 (although sufficient biasing may be available by the action of gravity alone). This lowermost axial position of the pinion is seen in full lines in Fig. 1.However, when the pinion 35 has been moved to its uppermost position indicated in dotted line in Fig. 1 and seen more clearly in Fig. 1 a, the pawls 60 are fully engageable between the ratchet teeth 61 and their innermost edges 62 penetrate inwardly further than the diameter of the cylindrical surface 65. Thus while they remain engaging between the teeth 61 their axially lowermost edge face abut against a lowermost shelf surface 63 at the foot of those teeth 61 and which is provided by an uppermost planar surface of the head 36. While they are so engaged downward movement of the pinion 35 is impossible whatever the biasing.

To cause the pinion to be moved to its uppermost position in which pawls 60 can engage with and penetrate between teeth 61 an actuating push button is provided which has a stem 80 and lock nuts 81 and 82 on a screwthreaded extension of the stem 80. Lock nut 82 has a rounded nose and abuts against a surface 83 of the arm 75. The stem 80 is axially moveable in a sleeve housing 84 secured to the base 5, and at its end outside the sleeve it is secured to a readily visible and accessible push button head 85. Screw 86 penetrates radially through the housing 84 and its end engages in a slot 87 in the stem 80 to define the limits of movability of the stem. A spring 88 is trapped between the end of the housing 84 and a washer behind the lock nut 81 and urges the stem 80 inwardly, but his spring is much weaker than spring 77 and is overridden by it.

To engage therefore the first drive train, the user of the winch presses the button 85 inwards causing rotation of the fork in an anticlockwise direction against the biassing of the sleeve 77, moving the pinion 35 to its uppermost position in which the pawls 60 are free to enter between the ratchet teeth 61. Once this position has been established the user is free to release pressure on the button 85 since as has been described, because the pawls remain engaged, the pinion will be held in its drive-engaging position for so long as drive is being transmitted through it upon appropriate rotation of the drive shaft 1.

When however the drive is reversed drive is established through the second gear train 45, 42, and a backward rotation will be imposed (back through gear 38) upon the pinion 35 which will therefore rotate in the opposite direction of the shaft 1 and its pawls 60 will click over the teeth 61 and thereby become free to slide onto the cylindrical surfaces 65 and cause their own permanent disengagement as the pinion moves downwardly down that surface under the influence of gravity and of the tension spring 77.

A further reversal of the drive shaft will cause not re-engagement of the first drive, since the pawls are still held free of the teeth 61, but will cause engagement of the third drive via gear ring 47 and ring 46.

The user may wish that upon any second reversal he will in fact revert to first drive ratio. In this case a lock can be provided upon the selector by virtue of a transverse extension 90 of the slot 87. Then, the user having depressed the push button inwardly gives it a quarter turn so that the end of the screw 86 is engaged in the L-shaped extension 90 and the push button is held locked in its inner position, in which teeth 60 and ratchet 61 are permanently engageable upon appropriate drive.

A second embodiment of the invention can be seen in Figs. 5 to 8. This illustrates that the principle of the invention may be applied to the sort of manually powered winch in which the lowest mechanical advantage drive train is a 1:1 drive between the drive shaft and the drum. In this winch the axially movable member which causes drive transmission through one drive train or disconnects drive transmission from that drive train is a coupling sleeve permanently meshed with a shaft coaxial with the shaft relative to which it moves axially.

In Fig. 5 only parts associated with this different form of axial member, and relevant to the changes made are shown since the remainder of the structure of the winch, and the selector mechanism which will operate the axially movable member are in substance as previously disclosed.

In this embodiment a winch drum 100 is rotatable on a conventional stationary frame structure schematically indicated at 101. It is secured to a top plate 102 within which is splined a ring 103 with radially inwardly directed ratchet teeth 1 04. A pawl 105 on a boss element 106 can drivingly engage with the ratchet teeth in a unidirectional drive. The boss element 106 includes a cylindrical part 107 mounted through bearing 108 inside the top end of the stationary structure 101 for rotation relative to it. A centre shaft 109 is borne within the boss part 106 and is splinedto it at 110. A retainer plate 111 is screwed to the shaft by screw 112 and bears down on boss 106. If the shaft 109 is rotated in one direction drive will be transmitted in a 1:1 ratio from it through the pawl 105 and ratchet 104, top plate 102 to drum 100.If the drive is in the opposite direction (or if the drum is overrunning the rotation of the shaft) the pawl will click on the ratchet teeth.

This embodiment is one in which drive is brought into the winch from underneath, but in principle it is identical (with appropriate reversal of undirectional drive linkages) to that where drive is brought to the top end of the centre shaft 109 direct from a handle.

At the lower end of the centre shaft 109 there is a widening on the outer face of which are formed ratchet teeth 11 5 analogous to teeth 61 of the previous embodiment. A member 11 6 is axially slidable upon the shaft, this member being analogous to pinion 25 of the first embodiment but differing from it in that, instead of meshing permanently with another gear in the relevant drive transmission (gear 38, Fig. 2, of the first embodiment) it is permanently enmeshed by means of inwardly directed spline teeth 11 7 with outwardly directed spline teeth 11 8 on a second shaft 11 9 mounted coaxially with the centre shaft 1 09 and rotatable relative to it.Its centerir g is assured by the projection of an end journal 1 20 of the shaft 119 to within a hollowed out end of the shaft 109, with the interposition of bearings 121 between them.

The member 11 6 taking the form of a coupling sleeve between the shaft 109 and 11 9 has mounted within it pawl 1 22 analogous to pawl 60 of the first embodiment. It has a channel 68 for engagement by a selector mechanism exactly as in the first embodiment, and a top plate 64.

It can be seen that the maximum diameter of the ratchet teeth 11 5, at region 1 23 is just somewhat greater than the minimum diameter of a chamfered-off top portion of the spline teeth 118, this portion being given the reference 125 in Fig. 5. Thus, exactly as in the first embodiment, when the member is in its axially upper position in which pawls 1 22 engage between teeth 115, and drive is transmitted between shaft 11 9 and shaft 109 in the appropriate direction, drive is thus transmitted via spline teeth 11 8 on shaft 109 and spline teeth 11 7 on the member 11 6 via pawl 1 22 on the member 116 to ratchet teeth 11 5 on the shaft 109. However if the direction of drive input is reversed the pawl 1 22 will click over the maximum diameter of the ratchet teeth 11 5 bringing it outwardly of the innermost diameter of the chamfered portion 1 24 of the splines 11 8 so that the member 116 is free to move either under gravity or under bias, exactly as described for the previous embodiment, to its lowermost position, that which is indicated in Fig. 5. In this position it can be seen that pawl 1 22 is held outwardly of maximum diameter of teeth 1 23 by abut ment on the land surface 1 25 (Fig. 7) of the spline teeth 11 8 on the shaft member 11 9.

The shaft is seen in more detail in Fig. 6 with land surfaces 1 25 chamfers 1 24 splinings 11 8 at end portion 1 20 clearly seen.

The shaft 11 9 also provides however a rotatable mounting for gear 1 26 analogous to pinion 47 of the first embodiment forming part of a successive drive train for this multispeed winch and which is a gear train. A pawl mounted within recess 1 27 (Fi.g 6) with the shaft 11 9 forms unidirectional driye means between that shaft and ratchet teeth 1 28 formed on the inner periphery of the pinion 126.

In the specific form being described drive is brought into this shaft complex by an end shaft 1 30 rotatably borne at the bottom end of the total shaft assembly in base structure 5" analogous to structure 5' of the first embodiment. The end shaft 1 30 has integrally formed in it pinion teeth 131 which (analogously with pinion 45 of the first embodiment) form part of a yet further drive ratio, which is also a gear train.Lower stub axle 1 32 of the shaft 119 is received in the hollow centre of the end shaft 130, the two shafts 11 9 and 1 30 being locked together for rotation together by interaction between plane faces 1 33 upstanding from the axially upper edge of the pinion teeth 1 31 with similar plane faces 1 34 on the lower end of the shaft 119, parallel said faces 1 33 on the shaft 1 30 being spaced apart one on each side of a diametrical plane passing through its axis and with a gap between them, faces 1 34 being correspondingly formed in and spaced apart by the solid material of the shaft 11 9.

Drive is brought into the assembly by the fitting of a key from a drive transmission train into keyed recess 1 35 at the extreme lower end of end shaft 130.

In operation the selector is operated against its spring bias to move the member axially upwardly to a position so that pawl 1 22 penetrates to between ratchet teeth 11 5 to transmit drive, as previously described, from shaft 11 9 to shaft 109 whence drive is derived via boss 106 and pawl and ratchet 105,104 in a 1:1 ratio by winch drum 100.

If the direction of drive input is reversed the pawl 1 22 clicks and the member 106 is free to move axially downwardly, as previously described. The reversal brings automatically into play the next drive ratio to the drum, through gear 131. A second reversal of the direction of drive input disconnects the unidirectional drive means in that drive ratio and engages, not the 1:1 drive ratio, but the third ratio-the gear train involving gear 126. The 1:1 drive is not engaged because, as described, in the lower position of the member 106 the pawl 1 22 is held disengaged from ratchet teeth 115, by being held on a land surface 1 25 of the spline teeth 11 8.

Claims (6)

1. A manually powered winch having a plurality of drive trains of progressively decreasing mechanical advantage between a re- versible drive input and the winch drum to rotate the drum in one direction and speed changing means for causing automatic sequential engagement of the said trains on successive reversals of the direction of rotation of the drive input, which has selector means available to the user for overriding the automatic change in respect of the trains of lower mechanical advantage whereby upon a second reversal of input direction the winch drum is driven through a first train which is the train of lowest mechanical advantage.

2. A manually powered winch according to claim 1, wherein the automatic speed change includes a movable member which in a first condition causes drive transmission in the first train the member being brought to that first condition by the selector means and normally automatically moving a second condition upon a first reversal to cause lack of drive transmission in the first train even upon second reversal, wherein the selector means includes a lock activatable to hold the member in its first condition.

3. A manually powered winch according to claim 2, wherein the member is an element of the first drive train and drive is transmitted through it.

4. A manually powered winch according to claim 2 or claim 3, wherein first and second conditions of the member are respective positions relative to a shaft and the member executes axial movement to change its condition, the lock holding the member in the first axial position.

5. A manually powered winch according to claim 2, claim 3 or claim 4 wherein, the member is held in its first condition by virtue of the drive transmission and is normally freed from that condition by cessation of drive transmission in the first train.

6. A manually powered winch according to claim 1 wherein the selector means includes a control knob accessible to the user outside the winch, depression of the knob towards the winch causing engagement of the first train, and includes also a lock for locking the knob in its depressed position to cause the said override.

6. A manually powered winch according to any one of the preceding claims wherein, the selector means includes a control knob accessible to the user outside the winch, depression of the knob towards the winch causing engagement of the first train, and includes also a lock for locking the knob in its depressed position to cause the said override.

7. A manually powered winch according to claim 6 wherein, the lock is caused by rotation of the knob.

8. A manually powered winch according to claim 7, wherein a stem of the knob includes a transverse detent slot engagable by a fixed pin by rotation of the knob in the depressed position for retention of the stem at that position.

CLAIMS (12 Jan 1981)

1. A manually powered winch having a plurality of drive trains of progressively increasing mechanical advantage between a re versible drive input and the winch drum to rotate the drum in one direction and speed changing means for causing automatic sequential engagement of the said trains on sucessive reversals of the direction of rotation of the drive input, which has selector means for the automatic change operable by the user to be unaffected by a first reversal so as to override the automatic change and prevent engagement of a third drive train upon a second reversal, so that upon the seond reversal of input drive direction the winch drum is driven through the first drive train which is the train of lowest mechanical advantage.

2. A manually powered winch according to claim 1, wherein the automatic speed changing means includes a movable member which in a first condition causes drive transmission in the first train, the member being brought to that first condition by the selector means and normally automatically moving to a second condition upon a first reversal to cause lack of drive transmission in the first train even upon second reversal, wherein the selector means includes a lock activatable to hold the member in its first condition and to be unaffected by the first reversal.

5. A manually powered winch according to claim 2, claim 3 or claim 4 wherein the member is normally held in its first condition by virtue of the drive transmission and is normally freed from that condition by cessation of drive transmission in the first train.