GB2312660A

GB2312660A - Pulley Drive Assembly

Info

Publication number: GB2312660A
Application number: GB9708675A
Authority: GB
Inventors: Alaric Waterson
Original assignee: MACTAGGART SCOTT
Current assignee: MACTAGGART SCOTT
Priority date: 1996-05-02
Filing date: 1997-04-30
Publication date: 1997-11-05
Anticipated expiration: 2017-04-30
Also published as: WO1999023026A1; GB2312660B; GB9708675D0

Abstract

A drive assembly (22 Fig 1) for a pulley (26, fig 3) comprises a first pulley (26) having a cable (20) passing around part of the pulley circumference. Three relatively small pulleys (30, 32, 34) are mounted on an assembly body (24) and a belt (36) extends around the pulleys. The belt (36) is driven and two of the small pulleys (30, 34) are located on a chord of the first pulley (26) such that tension in the belt (36) tends to bias the belt (36) to bear against the cable (20) as it passes around a portion of the circumference of the first pulley (26) located between the two small pulleys (30, 34). Preferably, the assembly is used to tow a sonar array from a submarine (10) with the cable being wound or unwound from a winch (18). In an alternative embodiment (Fig 4) an assembly (50) of pulleys and flexible belt is used to drive a ground engaging wheel (64) of an aircraft or vehicle e.g. on board a ship.

Description

DRIVE ASSEMBLY This invention relates to a drive assembly for a wheel which may be in the form of, for example, a pulley or a ground engaging wheel of an aircraft. The invention also relates to a method of driving a pulley or wheel.

The deployment, or veering, of cable from a winch drum is often achieved by applying a tension to the cable to draw it from the drum. In a number of applications this veering may be achieved by means of the load present on the cable, for example, in a towed sonar array as might be deployed from a submarine or ship, the array is deployed from a winding drum mounted on the vessel by means of the drag on the array created by the surrounding water.

However, initially, when only a short length of cable is deployed, the drag may not be sufficient to veer the cable from the winding drum and to pull the cable over the various pulley wheels that are provided between the drum and the point where the cable passes from the vessel.

Conventionally, such initial tension may be provided by locating a pair of driven rollers to form a nip beyond the last pulley wheel on the vessel. However, the point loads created by such a nip may damage the cable.

It is among the objects of at least one aspect of the present invention to obviate and mitigate this difficulty.

According to the present invention there is provided a drive assembly for a pulley, the assembly comprising: a first pulley adapted to accommodate a cable or the like passing around part of the circumference thereof; a body; at least three relatively small pulleys mounted on the body; a flexible member extending around the small pulleys; and means for driving the flexible member, two of the small pulleys being located on a chord of the first pulley such that tension in the flexible member tends to bias the member to bear against a cable passing around a portion of the circumference of the first pulley located between said two of the small pulleys.

The invention also relates to a method of applying a linear force to a cable or the like.

This arrangement allows a linear force to be applied to the cable without applying any significant radial loads thereto. Thus, the assembly may be utilised to deploy (veer) cable from a winch drum or wind (haul) cable onto a drum. The assembly may be provided directly on the winch drum, with the first pulley forming a part of the drum, or may be provided separately of the drum.

The invention has particular application in the deployment and retrieval of towed sonar arrays, in which the cable may be damaged if subject to high radial compressive forces. When deploying the array, the assembly may provide an initial tension to veer the cable from the winch drum. Then, once the drag on the array is sufficient to pull the cable from the drum, the assembly may run free.

However, when the drag on the array reaches a level where the remaining coils of cable on the winch drum may be subject to a compressive force sufficient to damage the cable the assembly may provide drag on the cable to reduce the tension in the cable between the first pulley and the winch drum. Further, the assembly may be utilised to haul the cable and retrieve the sonar array, allowing the cable to be wound onto the drum under minimal tension.

Preferably, one of the smaller pulleys is driven such that tension is created in the flexible member.

Preferably also, one of the smaller pulleys is mounted on the body via biassing means to impart an initial tension in the flexible member.

Preferably also, the flexible member is in the form of a belt, which may be toothed.

According to another aspect of the present invention there is provided an assembly for use in driving a wheel, the assembly comprising: a body; at least three pulleys mounted on the body; a flexible member extending around the pulleys; and means for driving the flexible member, two of the pulleys being locatable on a chord of a wheel to be driven such that tension in the flexible member tends to bias the member to bear on a portion of the circumference of a wheel located between said two of the pulleys.

The invention also relates to a method of driving a wheel.

The assembly may be provided in conjunction with a relatively large pulley wheel for providing drive for the pulley. Alternatively, the assembly may be utilised for driving a ground engaging wheel of a vehicle or aircraft to, for example, manoeuvre an aircraft on the deck of a ship. For such an application it is preferable that the said two of the pulleys are locatable relative to the wheel such that the flexible member extends around over half of the circumference of the wheel. Of course this provides a greater degree of friction between the flexible member and the wheel and also facilitates securing the assembly on the wheel. With such an arrangement it is also desirable that at least one of said two pulleys is movably mounted to facilitate mounting and dismounting of the assembly from the wheel.

Preferably, one of the pulleys is driven and imparts a tension on the flexible member.

Preferably also, one of the pulleys is mounted on the body via biassing means to impart an initial tension in the flexible member.

These and other aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a somewhat schematic plan view of a submarine including a towed sonar array deployment system including a drive assembly for a pulley in accordance with a preferred embodiment of the present invention; Figure 2 is a plan view of a drive assembly of the deployment system of Figure 1; and Figure 3 is a sectional view on line 3-3 of Figure 2; and Figure 4 is a somewhat schematic side view of a drive assembly in accordance with another embodiment of the present invention.

Reference is first made to Figure 1 of the drawings which illustrates a submarine 10 provided with a towed sonar array deployment system 12 incorporating a drive or pulley assembly 22 in accordance with a preferred embodiment of the present invention. The system 12 is utilised to deploy a towed sonar array from a winch drum 18 located within the hull of the submarine 10. From the drum 18, the cable 20 which connects the array to the submarine is passed around two pulley assemblies 14, 22 which ensure that the cable 20 clears the propeller of the submarine 24.

Reference is now made to Figures 2 and 3 of the drawings which illustrate the pulley assembly 22 in greater detail. The assembly comprises a casing 24 which accommodates a first relatively large pulley wheel 26 with an outer face 28 grooved to accommodate the cable 20 as it passes around the pulley 26. Mounted within the casing 24 are three smaller pulley wheels, 30, 32, 34 and a flexible belt 36 which extends therearound. Two of the pulleys 30, 34 are located on a chord of the larger pulley 26 such that tension in the belt 36 tends to bias the belt 36 to bear against the cable 20 as it passes around the first pulley 26. As will be noted from Figure 2, these two pulleys 30, 34 are located adjacent the respective points on the circumference of the pulley 26 where the cable 20 engages the pulley 26. One of the smaller pulleys 30 is mounted on the casing via a loading cylinder 38 to impart an initial tension on the belt 36. Another of the small pulleys 34 is driven by a hydraulic motor 40 mounted to the casing 24 via a housing 42 to create further tension in the belt 36.

In use, the pulley assembly 22 may be used in the initial deployment of the sonar array when the level of drag on the array and cable 20 in the water beyond the pulley 22 is insufficient to pull the cable 20 from the winch drum 18. The motor 40 is utilised to drive the belt in the direction of the arrows A, the motor 40 also causing the pulley 34 to apply tension to the belt 36 which clamps the belt 36 against the cable 20 on the pulley 26. The cable 20 is thus pulled from the winch drum 18 in the direction of the arrows B.

Once the drag on the portion of the array and cable in the water reaches a level which is sufficient to pull the array from the winch drum 18, the assembly 22 may be permitted to run freely. However, as the drag on the array increases it may be desirable to limit the tension in the cable 20 being pulled from the winch drum 18, and which would otherwise crush and damage the cable 20 remaining on the winch drum 18. Thus, the assembly 22 may be utilised to apply a drag to the cable such that the tension in the cable 20a between the pulley assembly 22 and the winch drum 18 is considerably lower than the tension in the cable 20b beyond the pulley assembly 22.

The assembly 22 may also be utilised to haul the cable 20 and retrieve the sonar array. Thus, if the belt 36 is driven in the opposite direction the cable will be pulled in while the winch drum 18 is rotated to wind the cable 20 onto the drum 18. Again, the tension in the portion of the cable 20a between the pulley assembly 22 and the winch drum 18 is considerably lower than the tension in the cable 20b beyond the assembly 22.

From the above description it will be seen that the pulley assembly 22 provides a simple and convenient means for veering or hauling the cable 20 and the use of the belt 36 to apply force to the cable 20 avoids the application of point loads to the cable 20 as would result from the use of conventional drive rollers.

It will be clear to those of skill in the art that the above described embodiment is merely exemplary of the present invention and that various modifications and improvements may be made thereto, without departing from the scope of the invention, for example, the large pulley 26 may be driven, rather than one of the smaller pulleys.

Further, although the above described embodiment is illustrated as operating in conjunction with a pulley 26, a belt and small pulley wheel arrangement could also be provided on a winch drum for deploying cable therefrom.

Also, by providing an assembly on a portable carrier an assembly 50 could be utilised to drive wheels of, for example, an aircraft on the deck of a ship, as illustrated somewhat schematically in Figure 4 of the drawings.

Such an assembly 50 includes a wheel-mounted body (not shown), carrying five small pulley wheels 52, 54, 56, 58, 60 with a belt 62 extending therearound. One of the pulleys 52 is driven and one of the pulleys 58 is mounted on the body so as to be movable to a position (shown in ghost outline) in which the assembly 50 can be wheeled, by an operator, to engage with, for example, the nose wheel of an aircraft 64 on the ground or the deck of a ship 66. The pulley 58 is then returned to a position adjacent the wheel 64 such that the belt 62 contacts a substantial portion of the circumference of the wheel 64.

Activation of the motor to drive the pulley 52 will create a tension in the belt 62, clamping the belt 62 against the wheel and, as the assembly 50 is restrained from rotating around the wheel 64 by contact with the ground/deck 66, driving the belt 62 will result in the wheel 64 rotating and the aircraft moving across the ground/deck 66.

Thus, this embodiment of the invention provides a simple and convenient arrangement for movement of aircraft over short distances.

Claims

1. A drive assembly for a pulley, the assembly comprising: a first pulley adapted to accommodate a cable or the like passing around at least a part of the circumference thereof; a body; at least three relatively small pulleys mounted on the body; a flexible member extending around the small pulleys; and means for driving the flexible member, two of the small pulleys being located on a chord of the first pulley such that tension in the flexible member tends to bias the member to bear against a cable passing around a portion of the circumference of the first pulley located between said two of the small pulleys.

2. The assembly of claim 1, in combination with a winch drum.

3. The assembly of claim 2, wherein the first pulley forms a part of the drum.

4. The assembly of claim 2, wherein the first pulley is provided separately of the drum.

5. The assembly of any of claims 2 to 4, wherein the invention is adapted for mounting on a ship or submarine for use in the deployment and retrieval of towed sonar arrays.

6. The assembly of any of the preceding claims, wherein at least one of the smaller pulleys is driven.

7. The assembly of any of the preceding claims, wherein one of the smaller pulleys is mounted on the body via biassing means to impart an initial tension in the flexible member.

8. The assembly of any one of the preceding claims, wherein the flexible member is a belt.

9. The assembly of claim 8, wherein the belt is toothed.

10. A method of applying a linear force to a cable or the like, the method comprising the steps of: passing a cable or the like around at least part of the circumference of a first pulley; passing a flexible member around at least three relatively small pulleys, two of the pulleys being located on a chord of the first pulley; and driving the flexible member such that tension in the flexible member tends to bias the member to bear against the cable passing around a portion of the circumference of the first pulley located between said two of the small pulleys.

11. The method of claim 10, utilised to deploy cable from a winch drum or wind cable onto a drum.

12. The method of claim 11, utilised in the deployment and retrieval of a towed sonar array.

13. The method of claim 12, wherein the first pulley is provided separately of the drum and when deploying the array an initial tension is provided to veer the cable from the winch drum; then, once the drag on the array is sufficient to pull the cable from the drum, the pulley is permitted to run free; and then when the drag on the array reaches a level where the remaining coils of cable on the winch drum may be subject to a compressive force sufficient to damage the cable the pulley provides drag on the cable to reduce the tension in the cable between the first pulley and the winch drum.

14. The method of claim 12 or 13, wherein, when the cable is hauled to retrieve the sonar array, the cable is wound onto the drum under minimal tension.

15. The method of any of claims 10 to 14, wherein one of the smaller pulleys is driven such that tension is created in the flexible member.

16. The method of any of claims 10 to 15, wherein one of the smaller pulleys is biassed to impart an initial tension in the flexible member.

17. An assembly for use in driving a wheel, the assembly comprising: a body; at least three pulleys mounted on the body; a flexible member extending around the pulleys; and means for driving the flexible member, two of the pulleys being locatable on a chord of a wheel to be driven such that tension in the flexible member tends to bias the member to bear on a portion of the circumference of a wheel located between said two of the pulleys.

18. The assembly of claim 17, wherein the assembly is adapted for driving a ground engaging wheel of a vehicle or aircraft.

19. The assembly of claim 17 or 18, wherein said two of the pulleys are locatable relative to a wheel to be driven such that the flexible member extends around over half of the circumference of the wheel.

20. The assembly of claim 17, 18 or 19, wherein at least one of said two pulleys is movably mounted to facilitate mounting and dismounting of the assembly from a wheel.

21. The assembly of any of claims 17 to 20, wherein one of the pulleys is driven and imparts a tension on the flexible member.

22. The assembly of any of claims 17 to 21, wherein one of the pulleys is mounted on the body via biassing means to impart an initial tension in the flexible member.

23. The assembly of any of claims 17 to 22, wherein the flexible member is a belt.

24. The assembly of claim 23, wherein the belt is toothed.

25. A method of driving a wheel, the method comprising: passing a flexible member around at least three pulleys; locating the pulleys relative to a wheel such that two of the pulleys are located on a chord of the wheel; and driving the flexible member such that tension in the flexible member tends to bias the member to bear on a portion of the circumference of the wheel located between said two of the pulleys.

26. The method of claim 25, wherein the wheel is a ground engaging wheel of a vehicle or aircraft.

27. The method of claim 25 or 26, wherein said two of the pulleys are located relative to the wheel such that the flexible member extends around over half of the circumference of the wheel.

28. The method of claim 25, 26 or 27, including moving at least one of said two pulleys to facilitate mounting and dismounting of the assembly from the wheel.

29. The method of any of claims 25 to 28, including driving one of the pulleys.

30. The method of any of claims 25 to 29, including biassing one of the pulley wheels to impart an initial tension in the flexible member.

31. The drive assembly substantially as described herein and as illustrated in Figures 1, 2 and 3 of the accompanying drawings.

32. The drive assembly substantially as described herein and as illustrated in Figure 4 of the accompanying drawings.