Winch

Abstract: A gypsy-type winch has a sheave (6) for driving a rope, chain or rope-chain pulling element (3). The pulling element (3) is urged into contact with the sheave (6) by a spring assembly (13) acting on the element (3) at positions (11,12) spaced apart from each other and in different sides respectively of a first diameter (21) extending between the inlet (4) and outlet (5) runs of the element (3), but both on one side of a second diameter (23) perpendicular to the first.

Description: This invention relates to winches according to the preamble of claim 1 and in particular to a form of winch known as a gypsy, in which a flexible pulling element takes a single turn around a driven rotatable sheave. The flexible pulling element may be a rope, a chain or a combination of these. The latter is most familiar in the marine context where the minor portion of the element closest to an anchor is usually chain but the major portion, that which is closer to the boat, may very well be rope. Such a winch is known from GB-A-1282985. Problems in this type of winch are ensuring as far as possible good grip between the sheave and the flexible element and these problems are particularly acute when the element is a mixed rope and chain and/or when there are irregularities in the flexible element such as twists, knots or thickenings. It has previously been proposed to provide a pivoting arm or a pivoting spring arm to urge the flexible element into the groove of the sheave. See for example GB-A-2233623, US-A-5402985 (both having pivoted arms) and WO-A-96/09980 where a part described as a guide arm is rigidly attached to a housing at one of its ends. A guide arm rigidly fixed at one end will if it is entirely rigid jam if there is any thickening in the flexible element passing it or will have to rely on its own inherent resilience to exert an effective force on that element. A problem with the sprung constructions is that they urge the flexible element inwardly only at one radius of the sheave so that, if it is desired to pay out rather than pull in the flexible element, there is no provision for maintaining what is now the incoming side of the element in contact with the sheave and it may escape, come loose, tangle or twist. The present invention aims to provide an efficient pressure exerting means for a winch of the gypsy type which at the same time allows for reversibility of the gypsy. The construction also is such that the passage of a thickening in the element at one radius of the winch will not affect deleteriously the operation of the device at other positions. The invention therefore provides a winch of the gypsy type as set out in claim 1 in which a flexible pulling element is urged into the groove of a rotatable sheave at two spaced apart radii of the sheave by a spring assembly. Preferred embodiments of the winch according to the invention are subject matter of the dependent claims 2-7. The gypsy may in particular be of the type intended to handle a rope/chain combination, that is one which has jaws adapted to engage both the rope and the links of chain. The invention also provides a method of improving the paying in and out of line from a gypsy-type winch which consists of applying spring pressure to a flexible pulling element lying in the rotatable sheave of the winch by means of a spring element extending around a major part of the sheave and urging the pulling element inwardly at at least two spaced radii of the sheave. A particular embodiment of the invention will be described with reference to the accompanying drawings wherein: Figure 1 is a top view of the sheave with an upper jaw of the sheave and an upper cover of a housing removed, to show a rope pulling element passing around the sheave; Figure 2 shows the same but where a join between a rope and chain is approaching the sheave; Figure 3 shows a chain engaged by the same sheave; Figure 4 is a face view of a spring element for the winch; Figure 5 is a diametrical section on the line V-V, Figure 1; Figure 6 is a top view of a second embodiment of spring element; Figure 7 is a face view of that element on the arrow 7 of Figure 6; Figure 8 is a view analogous to Figure 1 of a second embodiment of the invention; Figure 9 is a diametrical sectional view through the second embodiment; and Figure 10 is a top view of one of the loading arms. In Figure 1 a housing 1 of a gypsy-type winch is indicated in outline, and an inlet or outlet port 2 for a free end of a pulling element. The flexible pulling element here includes a rope 3 which passes from a tension run 4 to a free run 5. A sheave 6 of which the lower jaw only is shown in Figures 1-5 is rotatable about an axis of rotation 7. Together with the top jaw 28 (Figure 5) it forms a gripping and driving groove 29 for receiving a flexible pulling element such as the rope 3. In a manner known per se the plates are designed to accommodate either a rope such as 3 or a chain 8 (Figures 2 and 3), with chain link engaging sprocket teeth 9 arranged at equal pitches around the plates. By virtue of the conicity of the jaws the groove 29 formed between them tapers inwardly and can therefore accommodate, within limits, various dimensions of rope and/or chain. Between the runs 4 and 5 of the rope a plate 10 projects from a housing of the winch into the groove 29 to prevent rope or chain being carried around the whole of the circumference of the sheave. For efficient engagement especially of at least the rope portion of the flexible element with the sheave, it is desirable to urge it radially inwardly towards the narrower part of the groove 29. In the present invention this is achieved at two radii 11 and 12 of the sheave by means of a spring assembly which in this embodiment is a single spring element 13. This spring element has two arms 14 and 15 which diverge from a base 16 and have bent back ends 17 and 18 respectively forming a hairpin. This is looped round respective anchorage points which are posts 19,20 on the housing of the winch. It will be seen that the posts 19,20 are both on one side of a diameter 21 of the sheave through its axis of rotation but that the spring strip 13 extends around the sheave to the other side of that diameter. By virtue of the positioning of the posts 19,20 and the dimension of the base 16, radially inward pressure is exerted on the rope 3 at or about the radial positions 11 and 12. The spring strip is yieldable and Figure 2 shows what happens as the chain 8 approaches when the rope 3 of for example an anchor line has been fully pulled in. The rope 3 is joined to the chain 8 by a splice, knot or binding which has the effect of a considerable thickening in the rope as at 22, Figure 2. The figure shows how as this thickening 22 is brought into the groove 29 between the two jaws of the sheave the spring strip 13 can yield so that its arm 14 bulges while maintaining the inward contact at a radial position 11. This bulging of the arm 14 does not however affect the efficiency with which the other arm 15 of the spring strip continues to exert radially inward pressure on the rope 3 at a radial position 12. Indeed, the effect of the distortion of the arm 14 will be if anything to improve the contact between arm 15 and rope 3 at the radius 12. Figure 3 shows the situation when the chain 8 is passing around the sheave and out to the port 2. Now because of the increased effective thickness of the chain both arms 14 and 15 will bulge outwardly but both will maintain the desired radial contact at radii 11 and 12 respectively. Radial positions 11 and 12, respectively, may alter as the thickness of the pulling element, dependent on the shape of the arms and the geometry of the assembly. The discussion so far has concerned winding in of the line, that is to say with the sheave rotating clockwise as seen in Figures 1-4. However, a gypsy will also be used for paying out line, that is with the sheave rotating anti-clockwise as seen in those Figures. If no precautions were taken, the free end of the rope and/or chain could come up into the port 2, now the inlet port, in a tangled or twisted condition and if it entered the groove of the sheave in that state might jam the assembly. It can be seen that the spring being arranged symmetrically in relation to the diameter 23 which is generally parallel to the inlet and outlet runs of the flexible element, the arm 15 of the spring will act to provide efficient engagement of the run which is now the inlet run and will assist in smoothing out tangles or twists which might be in that line, as well as accommodating itself in the manner which has already been described to variations in thickness of that incoming element. Figure 4 shows a blank for forming the strip 13, showing tongues 24,25 which are destined to be on the ends of the turned back hairpin parts 17,18 of the spring and engage in recesses 26,27 in the floor of the housing of the winch adjacent the post 19,20, so as to bias the arms 14,15 inwardly to the desired extent and provide resistance, apart from that provided by the inherent resilience of the spring as against the further anchor post, to the bowing of the arm on the end of which they are to be found. Figure 5 shows how a base 30 of the housing 1 may be positioned on a floor such as a deck 31 of a vessel, and may contain reduction gearing 32 for driving the sheave from a motor 33 mounted below the deck 31. A modified form of spring assembly is seen at reference 35 in Figures 6 and 7. The arms 14',15' are rigid being pivoted on posts 19,20 as before, but at their free ends are united by a rubber cord 36, grooves in which are received in a keyhole slot 37 in the ends of the arms so as to draw the arms 14',15' resiliently together to exert the same actions as described previously on the rope passing round the sheave, in either direction of rotation. In a second embodiment of gypsy seen in Figures 8 to 10, like parts have like numbers as in the first embodiment. The spring assembly 45 in this embodiment is formed by two rigid arms 14",15" pivoted on posts 19,20 as before and drawn together by a tension spring 38 secured to them at positions 39,40 intermediate their length so as to draw them mutually together and have once more the same action as the spring assemblies of the first embodiment, with contact positions 11",12" respectively which, since the arms are curved, will vary with the thickness of the pulling element. Figure 8 shows these arms in their outermost positions, that is with the spring 38 at greatest tension. Figure 9 shows how the arms (only one being shown) are urged to swing inwardly to press on rope 3. The arms 14",15" are of part-tubular construction. A central portion 41 (Figure 10) is tubular but end portion 42 is of channel section until it forms an aperture 43 for anchor post 19,20, and end portion 44 is also of channel section into which the tension spring 38 can enter, helping the spring to be snag-free in its operation as it extends and contracts.

Claims: A winch with a driven rotatable sheave (6) and means (13,35,45) for contacting a flexible pulling element (3,8) to urge it radially towards the sheave between inlet (4,5) and outlet (5,4) runs at a plurality of circumferentially spaced-apart contact positions (11,12,11',12',11",12") around the circumference of the sheave (6), said plurality of contact positions including two (11,12,11',12',11",12") which are located symmetrically one at either side of a diameter (23) which passes through the axis of rotation (7) of the sheave and which passes between the inlet (4,5) and outlet (5,4) runs, characterised in that the means is a spring assembly (13, 35, 45) for resiliently urging the pulling element (3, 8) inwardly. A winch according to claim 1, in which the spring assembly has anchorage points (19,20) in a body of the winch at each of its ends, and the spring assembly (13,35,45) extends between the anchorage points (19, 20) around the sheave (6) on one side of a second diameter (21) through the axis of rotation (7) to provide said contact positions, the second diameter being perpendicular to the first-mentioned diameter (23) and said two contact positions being on said one side of the second diameter. A winch according to claim 1 or 2 which is for reception of a flexible pulling element which has serially a rope (3) and a chain (8), the sheave (6) having a toothed portion (9) adapted for reception of the chain (8) and the spring assembly being effective to urge at least the rope (3) into contact with the sheave. A winch according to any one of claims 1 to 3, wherein the spring assembly (13,35,45) is for contacting the flexible pulling element (3,8) at said two contact positions (11,12,11',12',11",12") only. A winch according to any one of claims 1 to 4, wherein the spring assembly is a single spring member (13) for engaging the flexible pulling element (3,8) by respective arms (14,15) thereof. A winch according to any one of claims 1 to 4, wherein the spring assembly comprises rigid arms (14',15',14",15") pivoted at the anchorage points (19,20) respectively and drawn together by a spring element (36,38) extending between them. A winch according to claim 6, wherein the arms (14",15") are tubular (41) in section over part of their length but include a channel-section portion (42).

Inventors: HENLY NICHOLAS CHARLES, HENLY, NICHOLAS CHARLES
Applicants: LEWMAR LTD, LEWMAR LIMITED
Application year: 1998
Main classification: B66D1
IPC codes: B66D1