GB2430424A

GB2430424A - Pulley block

Info

Publication number: GB2430424A
Application number: GB0519035A
Authority: GB
Inventors: Giles Smith
Original assignee: Allen Brothers Fittings Ltd
Current assignee: Allen Brothers Fittings Ltd
Priority date: 2005-09-17
Filing date: 2005-09-17
Publication date: 2007-03-28
Also published as: GB0519035D0

Abstract

A pulley block for use for example on a racing dinghy has a block body 12 between the side cheeks 13,14 of which is rotatably mounted a pair of sheaves 11, with a separator 16 therebetween. A transverse opening 21 extends through the block body, internally of the sheaves 11. A slot 23 is formed through the separator 16 at an end of the block remote from a mounting pin 18, a becket member 25 extending through the slot to project externally of the block body. A locking pin 31,32,33 is provided within the transverse opening 21 to restrain the becket member within the slot 23.

Description

S

PULLEY BLOCK

This invention relates to a pulley block and in particular to a pulley block which may be provided with a becket, if required.

Though a pulley block of the kind with which this invention is concerned may be used in a variety of circumstances, it has a particular application in relation to small racing boats such as dinghies, catamarans and the like. As such, the invention will be described exclusively with reference to a pulley block for those uses, though the invention is not to be regarded as limited thereto.

Pulley blocks are used extensively on the running rigging of racing dinghies (which term is used herein to include other racing boats such as catamarans), to assist in the hoisting and trimming of the sails, controlling the boom and in association with other lines used on dinghies. Particularly on racing dinghies, such pulley blocks are required to have sheaves which may rotate with low friction in order to minimise losses and also to have relatively low weights. Further, such pulley blocks are frequently highly stressed and so must display great strength in order not to fail at inconvenient times. As a consequence of these demands, pulley blocks for racing dinghies tend to be relatively expensive items.

A typical pulley block has a mounting pin which permits the block to be connected to some other component, such as a fixed part of a dinghy. In addition, it is known to provide a pulley block with a becket - that is to say, a facility whereby a line or shackle may be terminated to the body of the pulley block. Such a becket is provided on the pulley block body at a position angularly spaced from the block mounting pin, and typically diametrically opposed thereto, having regard to the sheave. A typical becket comprises a metal plate projecting radially from the body of the block though it is known to provide a flexible becket for example of cord or webbing.

In genera!, the becket must be provided as a part of the block, during manufacture. As such, a retailer of pulley blocks will have to stock essentially similar blocks in both without becket and with becket varieties. This increases the amount of stock a retailer has to carry, the display space required to display both varieties of block and also the value of the stock held by the retailer.

This invention aims at addressing the problem of providing essentially similar blocks either without or with a becket, in a simple and costeffective manner.

Accordingly, this invention provides a pulley block comprising: - a block body defining a pair of opposed side cheeks and a separator disposed therebetween; - at least two annular sheaves mounted side-by-side between the cheeks and separator, the side cheeks and separator rotatably mounting the sheaves and there being a transverse opening extending through the side cheeks and separator within the annular sheaves, the separator having a slot formed therein which extends in the plane of the separator from an outer edge thereof to the transverse opening thereof; and - a becket arrangement including a member located in the slot in the separator and projecting into the transverse opening, the member also projecting externally of the block body to permit the attachment thereto of another component, and locking means within the transverse opening to resist a load applied to the member externally of and away from the block body.

By providing a separator which defines a slot for carrying a becket and also providing a locking means for a becket furnished in that slot, it becomes possible to add a becket to a pulley block at the time of purchase of the block or subsequent thereto. In turn, this means that a retailer does not need to stock pulley blocks provided with beckets; rather, the retailer may stock only pulley blocks without beckets and also stock a supply of beckets with locking means therefor, suitable for use with those pulley blocks. In the event that a purchaser requires a block with a becket, that may be provided at the point of sale.

Except for the configuration of the separator between the sheaves, the block body may be essentially conventional. Thus, the block body may include a bridging member externally of the sheaves and interconnecting the side cheeks. The separator may be formed integrally with the block body or may be separately formed and connected to the bridging member, in a similar manner to that employed with conventional blocks having two sheaves. In addition to the bridging member, the side cheeks and separator may also be connected together within the space defined within the annular sheaves, so long as the transverse opening is still left clear, for fitting the locking means of the becket arrangement.

In a particularly preferred pulley block of this invention, the block body comprises two similar mouldings each defining a side cheek and part of the bridging member, which mouldings are clamped together by suitable fastenings with the separator disposed centrally therebetween.

The slot in the separator may be substantially diametrically opposed to the bridging member, in order that the becket member may project from the block at a diametrically opposed position to the mounting pin for the block.

In one embodiment of this invention, the member of the becket arrangement comprises a flexible strap extending in the plane of the separator, in the slot therein. The inner end of the strap (that is the end within the transverse opening of the block body) may be secured by a suitable clamp arrangement so as to resist withdrawal from the slot by force applied to the strap externally of the block body and in a direction away therefrom. In this case, the part of the strap external to the block may be preformed with a loop, for example to permit the tying of a line thereto. Alternatively, the strap may be formed into a loop with the two ends of the strap being disposed within the transverse opening of the block body and being secured therein by the locking means, with two portions of the strap being disposed in the slot. A further possibility would be to provide two generally parallel slots in the separator, with one portion of the strap in one slot and the other portion in the other slot.

Various locking means may be provided for the strap, depending upon the structure thereof. For example, a screw-threaded clamp could be provided, or a buckle arrangement for the two ends of the strap. In either case, the strap could have a sufficient length to permit the connecting of the ends of the strap to the locking means when disposed externally of the block body whereafter the loop in the strap is pulled away from the block body until the locking means engages the separator, within the transverse opening. To ensure stability in use and to facilitate assembly, a spacer may be provided between the transverse opening in the separator and the locking means.

As an alternative to a flexible strap, the becket arrangement may have a substantially rigid metal or plastic member which extends through the slot in the separator with the inner end of the member furnished with a locking means to prevent the member being pulled radially away from the block, out of the slot.

The locking means may comprise one or more pins extending through corresponding holes formed in the plate at the inner end thereof. Each such pin should be provided with means to prevent inadvertent removal and so may comprise a screw-threaded fastener. An alternative would be to provide a lock member to at least one side, but preferably both sides, of the inner end of the becket member, the or each lock member being held in position by a screw- threaded fastener which also extends through a hole in the member. A pair of lock members may be provided, one to each side of the inner end of the becket member, or a single lock member with a slot therein to receive the inner end of the becket member.

In the foregoing, it has been presumed that the pulley block comprises a double block, with two sheaves side-by-side and with the separator extending therebetween. The invention is however equally applicable to pulley blocks having more than two sheaves. For example, in the case of a triple pulley block, corresponding separators may be provided to each side of the central sheave and the becket member may be mounted in the slots in both of those separators. Thus, for a becket member in the form of a flexible strap, a loop may be formed by portions of that strap extending through the slots in the two separators respectively. Greater strength may be achieved by having a single strap formed into two loops crossing over externally of the pulley block with an internal loop within the transverse opening but constrained therein by a part extending through that internal loop, and the ends of the strap secured together within the transverse opening. Alternatively, two separate straps could define loops which cross over externally of the pulley block and the four ends of those straps being secured by the locking means within the transverse opening.

In a similar way, a metallic or pre-moulded plastics becket member may have a U-shape or a Y-shape with the arms thereof extending through the slots in the two separators, respectively, of the block body and the ends thereof being secured by the locking means within the transverse opening.

Alternatively, substantially rigid planar becket members may be employed with a rigid bridging part provided between those members externally of the block, so that a line may be secured thereto.

In the case of a quadruple block, a separator formed with a slot as described above could be provided between the outer sheaves and the next adjacent sheaves, such that a flexible strap or metallic U-shaped or 1shaped becket member could be arranged in the slots of those separators. In the alternative, a single separator with a slot for the becket member could be provided between the two inner sheaves.

By way of example only, several specific embodiments of pulley block of this invention will now be described in detail, reference being made to the accompanying drawings in which:- Figures 1 and 2 are respectively side and edge views of a first embodiment in the form of a double pulley block fitted with a becket arrangement including a flexible strap becket member, parts being cut away for clarity; Figures 3 and 4 are similar to Figures 1 and 2 but with the double pulley block fitted with a becket arrangement having a metallic becket member; Figures 5 and 6 are respectively side and underneath views of a triple pulley block fitted with a becket arrangement including two flexible strap becket members, again parts being cut away for clarity; and Figure 7 is a side view of the pulley block of Figure 5 but fitted with a metallic becket arrangement.

Referring initially to Figures 1 and 2, there is shown a first embodiment of pulley block 10 having a pair of annular sheaves 11 rotatably mounted side- by-side within the block body 12. The body includes a pair of opposed side cheeks 13,14 together with a bridging piece 15 extending therebetween, and a separator 16 disposed centrally between the side cheeks and connected to the bridging piece. Each sheave 11 is rotatably supported between a side cheek and one side of the separator 16, by balls running in tracks formed respectively on the sheave and on the side cheeks and separator. A metal strap 17 extends externally of the side cheeks and over the bridging piece and retains in position a rotatable mounting pin 18. The block is held together once assembled by means of fastenings 19,20 extending transversely through the block body 12 and the strap 17. Fastening 19 passes through the bridging piece 15 whereas fastening 20 extends through a transverse opening 21 in the side cheeks and the separator, within the bore of the annular sheaves. Such a construction of a double pulley block is essentially conventional and will not be described in further detail here.

The separator 16 is formed with a slot 23 extending generally radially from the outer periphery of the separator to the transverse opening 21. The slot is formed within the thickness of the separator so that the tracks on the separator for the balls mounting the sheaves are continuous and not interrupted by the slot. Typically, in the region of slot 23, the separator may have a thickness of 3.3 mm with the slot having a width in the direction of the sheave axis of 1.8 mm.

In this embodiment, the becket is formed by a strap 25 cut and sealed from a length of webbing. Two portions 26,27 of the strap extend side-by- side through the slot 23 in the separator 16 so that the two ends of the strap are disposed within the transverse opening 21 and there is formed a loop 30 externally of the pulley block 10. The two portions 26,27 extend through a slot formed in a spacer 31 disposed within the transverse opening 21 and the two strap end parts are locked by a buckle 32 which bears on the spacer 31. The buckle comprises a plate having a transverse opening together with a bar 33, each strap end extending through the opening, around the bar and back through the opening as best seen in Figure 2. By appropriate configuration of the buckle, the strap 25 is locked in position within the transverse opening 21 so as to be able to resist tension applied to the loop 30, away from the block 10.

By making the strap 25 sufficiently long, the ends thereof may be pulled out of the transverse opening 21 to enable the engagement thereof with the buckle 32 while still leaving a small loop 30 accessible externally of the pulley block. Then, once the two ends have been secured to the buckle, the loop may be pulled to bring the buckle into engagement with the spacer 31, whereafter the becket is ready for use.

Figures 3 and 4 show an alternative becket arrangement for the block 10 of Figures 1 and 2. Instead of providing a length of webbing to serve as the becket, in the arrangement of Figures 3 and 4 there is provided a becket plate 35 of sheet metal such as stainless steel, which defines an eye 36 externally of the pulley block, to permit the connection thereto of a shackle, a line or the like.

The becket plate has a pair of arms 37 which extend through the slot 23 into the transverse opening 21, each arm having at its internal end a hole 38. A clamp 39 has a slot in which the arms 37 are received, the clamp having through-holes aligned with the holes 38 of the arms 37 and the holes on one side of the slot being screw-threaded such that screws 40 may be received in the through-holes and the holes 38 of the arms, as shown in Figure 4, to secure the becket plate to the clamp 39. Once attached in this way, the becket plate will be locked in position and able to withstand force applied to the eye 36, in the direction away from the block.

Access may be gained to the bars 39 and screws 40 through the transverse opening 21 so facilitating assembly. Also, as shown in Figure 3, the metal becket plate 35 may be profiled so as to engage shoulders 41 in the slot 23 in the separator 16 so as to prevent radially inward movement of the external part of the becket plate and locate the plate in the circumferential direction. In other respects, the assembly corresponds to that of Figures 1 and 2 and so will not be described further, here.

Figures 5 and 6 show an arrangement similar to that of Figures 1 and 2, but for a triple pulley block 43. Like parts with those of Figures 1 and 2 are given like reference characters but this block 43 differs from block 10 in that three sheaves 11 are provided, along with two separators 16 disposed one to each side of the central sheave, each separator having a slot 23. In this embodiment, two straps 44,45 are provided, each strap being similar to strap 25 of the arrangement of Figures 1 and 2. Each strap 44,45 has its two ends connected to a respective buckle 46,47 such that each buckle secures one end of each strap. As shown in Figure 6, it is preferred for the straps to cross over externally of the pulley block so as to provide a high-strength point for securing a line, though it would be possible to have the loops of the two straps lying side- by-side, externally of the pulley block. The lengths of the two straps should be adjusted using the buckles, so that any load applied to the becket is shared equally by the two straps.

As shown in Figure 5 (but not in Figure 6), a spacer 48 is disposed externally of the pulley block adjacent the slots 23 in the separators 16, to ensure the straps 44,45 remain in the correct required disposition and do not jam against each other in the slots. Further, the spacer 48 prevents the cheeks collapsing on to the sheaves when the becket is under load. In other respects, the arrangement of Figures 5 and 6 is similar to that of Figures 1 and 2 and moreover is used in the same manner.

Figure 7 shows the pulley block of Figures 5 and 6, but used with a pair of metallic becket plates 35 each of which has the same configuration as the becket plate 35 of Figures 3 and 4. Each such becket plate has a pair of arms secured within the transverse opening by clamp bars 39 and screws 40, as described above. Externally of the pulley block 43, the eyes 36 in the two becket plates support a profiled pin 49 locked in place by nuts 50 so as to extend between the two plates 35. In other respects, the arrangement is as has been described hereinbefore and is used in the same manner.

Claims

1. A pulley block comprising: - a block body defining a pair of opposed side cheeks and a separator disposed therebetween; - at least two annular sheaves mounted side-by-side between the cheeks and a separator, the side cheeks and separator rotatably mounting the sheaves and there being a transverse opening extending through the side cheeks and separator within the annular sheaves, the separator having a slot formed therein which extends in the plane of the separator from an outer edge thereof to the transverse opening thereof; and - a becket arrangement including a member located in the slot in the separator and projecting into the transverse opening, the member also projecting externally of the block body to permit the attachment thereto of another component, and locking means within the transverse opening to resist a load applied to the member externally of and away from the block body.

2. A pulley block as claimed in claim 1, wherein the block body includes a bridging member externally of the sheaves and interconnecting the side cheeks, the separator being connected to the bridging member, between the sheaves.

3. A pulley block as claimed in claim 2, wherein the side cheeks and separator are also connected together within the space defined within the confines of bore of the annular sheaves.

4. A pulley block as claimed in claim 3, wherein the block body comprises two similar mouldings each defining a side cheek and part of the bridging member, which mouldings are clamped together by fastenings with the separator disposed centrally therebetween.

5. A pulley block as claimed in any of claims 2 to 4, wherein the slot in the separator is substantially diametrically-opposed to the bridging member, with respect to the sheaves.

6. A pulley block as claimed in any of the preceding claims, wherein the member of the becket arrangement comprises a flexible strap.

7. A pulley block as claimed in claim 6, wherein the flexible strap is formed into a loop with strap portions passing through the slot in the separator so that the two ends of the strap are disposed within the transverse opening.

8. A pulley block as claimed in claim 7, wherein the two ends of the strap are secured by a clamp arrangement so as to resist withdrawal from the slot by force applied to the strap externally of the block body and in a direction away therefrom.

9. A pulley block as claimed in claim 6, wherein one end of the flexible strap is disposed within the transverse opening and is secured there by a clamp arrangement so as to resist withdrawal from the slot by a force applied to the strap externally of the block body, and the end of the strap externally of the block body is formed into a loop to serve as a becket.

10. A pulley block as claimed in any of claims 6 to 9, wherein a buckle is disposed within the transverse opening, the or each end of the flexible strap being connected to the buckle.

- 14 -

11. A pulley block as claimed in claim 10, wherein a spacer is disposed in the transverse opening, the spacer having a passageway though which the strap extends and the buckle bearing on the spacer.

12. A pulley block as claimed in any of claims 1 to 5, wherein the member of the becket arrangement comprises a substantially rigid plate, one end of the plate being disposed within the transverse opening and the other end of the plate lying externally of the pulley block and being configured for the attachment of a component thereto.

13. A pulley block as claimed in claim 12, wherein the locking means comprises a fastener extending through a bore formed in said one end of the becket plate, within the transverse opening.

14. A pulley block as claimed in claim 13, wherein at least one lock member is provided within the transverse opening, said fastener extending through the bore formed in said one end of the becket plate and also through the lock member.

15. A pulley block as claimed in claim 14, wherein a pair of lock members are provided, one to each side of said one end of the becket plate and a screw- threaded fastening extends through one of the lock members and the hole in said one end of the plate, and into a screw-threaded hole in the other lock member.

16. A pulley block as claimed in claim 14, wherein the lock member comprises a bar formed with a slot to receive said one end of the becket plate, the fastener extending through the bar to each side of said one end of the - 15- becket plate as well as through the bore formed in said one end of the becket plate.

17. A pulley block as claimed in any of the preceding claims, wherein there are three coaxial annular sheaves arranged side-by-side within the block body between the side cheeks thereof, and a pair of separators disposed one to each side of the central sheave respectively, each said separator being formed with a slot for receiving a becket arrangement.

18. A pulley block as claimed in claim 17 and in which the becket arrangement comprises a flexible strap, one end portion of the strap extending through the slot of one separator and the other end portion of the strap extending through the slot of the other separator.

19. A pulley block as claimed in claim 18, wherein the becket arrangement comprises a pair of flexible straps each similarly disposed with respect to the slots in the separators and the straps crossing over externally of the pulley block.

20. A pulley block as claimed in claim 17, wherein the becket arrangement comprises a pair of substantially rigid plates disposed one in the slot of each separator respectively and each becket plate being configured for the attachment of some other component thereto, externally of the block.

21. A pulley block as claimed in claim 20, wherein each becket plate has an eye formed externally of the block and a pin extends between the eyes of the two plates.

22. A pulley block as claimed in claim 1 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.