EP0084606A1

EP0084606A1 - Cable pinching sheave

Info

Publication number: EP0084606A1
Application number: EP82109557A
Authority: EP
Inventors: Thomas Joseph Reynolds; Jagdish Chandra Kalyan
Original assignee: Western Gear Corp
Current assignee: Western Gear Machinery Co
Priority date: 1982-01-04
Filing date: 1982-10-15
Publication date: 1983-08-03
Also published as: NO830007L; JPS58167355A; AU8962382A

Abstract

A pinching sheave (10) for continuously engaging and pulling in or paying out cable or other flexible conduit. A cable (100) is placed on the rim of an inner disc assembly (16) which is mounted on a rotatable shaft (20). Pinching discs (40, 41) mounted on each side of the inner plate are pivoted toward the inner plate to apply a pinching force to the cable. The shaft is rotated, requiring movement of the "pinched" cable.

Description

Technical Field

This application pertains to devices for retracting or paying out cables or other flexible conduits, and more particularly, to an improved sheave for maximizing the friction between the sheave and such conduits by applying a pinching force to the conduits.

Background Art

Devices which retract or pay out cables or other flexible conduits are used in a variety of fields. In a marine environment, these devices are used to haul in fish- pots, nets, and other similar units. In underground mining operations, these devices, are used to extend and retract the electrical cables which power mining vehicles. Whenever mobility of one or all objects joined by a cable, line or other flexible conduit is required, a suitable means of retracting and paying out the conduit is needed.
One method of retracting or paying out conduits is to simply wind and unwind the conduit on a spool. Although this method is acceptable for some uses, it has inherent drawbacks. As a conduit is retracted, the portion of the conduit being wound around the spool may be subjected to excessive stress. Additionally, unless there is a constant pulling force in. the direction of payout, unwanted slack may result when the spool is unwound.
The difficulties mentioned above can be eliminated by using a sheave which can temporarily grasp and pull in or pay out the conduit. Sheaves of this type may be used in conjunction with a spool or other system of stowing retracted or unused conduit, such as that disclosed in U.S. Patent No. 4,258,834. The axial force that a sheave is capable of exerting on a conduit or cable is limited by the magnitude of the friction between the sheave and cable. If the friction is insufficient in relation to the axial load on the cable, the cable will slip on the sheave.
Devices now used for grasping and continuously pulling a conduit are exemplified by the power sheave disclosed in a patent to Haines, U.S. Patent No. 3,635,441, entitled "Fishing Apparatus and Sheave Therefor." The sheave of the Haines patent utilizes a pair of discs which are resiliently biased toward each other. The rotational axes of the discs are angled with respect to each other so that the top portion of the discs grips a cable while the bottom portion releases it. Devices of the Haines type are not well suited for use with all conduits in that the convex surfaces of the discs tend to force a cable outward. Additionally, no means is provided to vary the force exerted on a cable during operation.
Another type of sheave device is disclosed in Hawley et al., U.S. Patent No. 4,258,834, entitled "Winding System for Flexible Conduits and Cables." The Hawley et al. patent discloses a drive mechanism which engages a cable between a rotating rim with an integral side flange and a movable flange which is biased toward the cable by a hydraulic ram.

Disclosure of the Invention

It is an object of this invention to provide a device for retracting and paying out cables or other flexible conduits which will provide sufficient frictional engaging of such conduits.
It is another object of the invention to provide a device for retracting and paying out cables or other flexible conduits which will permit variable force to be exerted on the cable while in operation.
It is another object of the invention to provide a device for retracting and paying out cables or other flexible conduits which permits quick disengagement of the conduit being retracted or paid out.
It is a further object of the invention to provide a device for retracting and paying out cables or other flexible conduits which is capable of accommodating a variety of conduit diameters.
These and other objects of the invention are accomplished by a rotating disc assembly which receives a length of cable. The cable rests on the rim of an inner plate which is mounted between two side discs on a common shaft which is rotated by a hydraulic motor. Respective rollers engage the outer ends of each side disc and push it inward to pinch the cable resting on the rim of the inner plate. A hydraulic cylinder biases each roller against its respective side disc and permits the application of variable amounts of pressure on the side discs by the rollers. Additionally, the hydraulic cylinder permits a quick release of the pressure on the side discs when desired, and it allows the side discs to separate in response to variations in the diameter of the cable.

Brief Description of the drawings

Fig. 1 is an isometric view of a cable binding sheave with the housing partially cut away to expose the hydraulic motor.
Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1.
Fig. 3 is a plan view of the roller assembly.
Fig. 4 is a cross-sectional view taken about line 4-4 of Fig. 2.
Fig. 5 is a cross-sectional view taken about line 5-5 of Fig. 2.

Best Mode for Carrying Out the Invention

The cable-pinching sheave 10, as illustrated in Figs. 1 and 2, is designed to receive a length of cable 100 within a rotating disc assembly 16, pinch the cable after it is placed within the disc assembly 16, and then extend or retract the cable by rotating the disc assembly 16.
The rotating disc assembly 16, best illustrated in Fig. 2, is comprised of a centrally located splined shaft 20 on which a circular center plate 30 and two pinching discs 40,41 are mounted. The center plate 30 has a relatively wide inner base 34 which interlocks with the spline shaft 20. The main portion of the center plate 30 is provided with a plurality of weight reduction holes 32 and extends radially outward from the base, terminating in an outer rim 36 which engages the underside of the cable 100, as shown in Figs. 2 and 5.
As shown in Fig. 4, each pinching disc 40,41 is comprised of three interfitting sections. An inner disc 42 interlocks with the spline shaft 20 at a location abutting one side of the inner base 34 of the center plate 30 (see Fig. 2). The inner disc 42 projects radially outward and terminates in a relatively narrow flange 47 positioned centrally on the body of the inner disc, as shown in Fig. 2.
The middle section of each pinching disc 40,41 is an elastic fitting 43 which forms an H-shaped ring extending radially outward from the inner disc 42. The inner slot of the H-shaped elastic fitting 43 fits snugly about flange 47 to connect the elastic fitting 43 to the inner disc 42.
The third section of each pinching disc 40,41 is the outer ring 44. A flange 48 extends inwardly from the outer ring 44 into the outer slot of the H-shaped elastic fitting 43, as shown in Fig. 2. The elastic fitting 43 thus forms a resilient connection between the inner disc 42 and the outer ring 44, which permits the outer ring 44 to pivot inwardly about the flange 48 in a direction along the longitudinal axis of the splined shaft 20 when subjected to pinching forces, as discussed below.
In manufacturing the pinching discs 40,41, the inner disc 42 and the outer ring 44 are positioned on a flat surface with the proper spacing. Rubber is then poured between the plates and vulcanized under heat and pressure. The flanges 47,48 are machined in the inner disc 42 and outer ring 44 prior to assembly to provide a sufficient metal-to-rubber contact area.
The inner discs 42 and outer ring 44 each have weight reduction holes 46,45 evenly spaced at locations a common distance from the rotational axis of the splined shaft 20. The weight reduction holes 46,45 help to minimize the overall weight without sacrificing necessary strength.
It should be understood that although the cable pinching discs 40,41 described above are coupled to the shaft 20 via the interlocking connection between the splined shaft 20 and the inner discs 42, other suitable means of coupling are also possible. The outer rings 44, for example, can be resiliently connected to the circular center plate 30, eliminating the need for the inner discs 42.
The rotating disc assembly 16 is coupled to a hydraulic motor 110 capable of rotating the splined shaft 20 either clockwise or counterclockwise. A servo valve 1.20 is used to provide quick change of rotational direction.
The rotating disc assembly 16 is mounted within a housing 12 by means of bearings 13 positioned around the splined shaft 20 at a location near each end of the shaft. A seal ring 15 is positioned between the bearings 13 and each pinching disc 40,41. The ends of the splined shaft 20 are threaded and receive securing nuts 17 on each end which are adjusted inwardly to properly tighten the rotating disc assembly 16. A bearing housing 19 surrounds each end of the splined shaft 20 and is secured to the housing 12 by screws 18, as shown in Fig. 2.
When the cable-pinching sheave 10 is operated, a length of cable 100 is placed on the edge of the outer rim 36. The sides of the cable are engaged by the outermost portion of the inner sides of the pinching discs 40,41, as shown in Fig. 2. A hydraulically adjustable roller assembly 50 and a manually adjustable roller assembly 60 rollably engage the outer side of pinching discs 40 and 41, respectively, at locations opposite the cable 100. Each roller assembly 50,60 is adjustable to deliver a variable amount of force inwardly on its corresponding pinching disc 40,41, causing the portion of the pinching disc 40,41 near the roller assemblies to pivot inward toward the cable while simultaneously pivoting outward the portions of the pinching discs 40,41 radially opposite said portions. As the pivoting pinching discs 40, 41 engage the cable 100, each exerts a force on the cable 100. This force has a sideways component directed toward the center of the cable 100 and, because the outer edges of the discs 40,41 are inclined inwardly, a radial component directed toward the longitudinal axis of the splined shaft 20. These forces thus not only combine to "pinch" the cable between the two pinching discs 40,41, but they also force the cable 100 against the rim 36 in order to increase the frictional force therebetween. When the pinching discs 40, 41 and rim 36 are rotated by the hydraulic motor 110, and sufficient pinching force is applied to the cable 100, the cable 100 is required to move in conjunction with the discs 40,41 and rim 36, resulting in the extension or retraction of the cable.
The hydraulically adjustable roller assembly 50 discussed above is illustrated in Fig. 3. A pair of mounting brackets 57,58 connect the roller assembly 50 to the housing 12. The rear bracket 58 supports the rear end of a hydraulic cylinder 52. An extendable piston shaft 53 projects from the nonsupported end of the hydraulic cylinder 52. A pair of triangular plates 54 with rounded corners are pivotally mounted to the front bracket 57 near one corner of the plates 54. The projecting end of the piston shaft 53 is mounted between the two plates at a location near a second corner. A roller 56 is rotatably mounted between the two plates at a location near the final corner, as illustrated in Fig. 3. When the pressure inside the hydraulic cylinder 52 is increased, the piston shaft 53 extends out of the hydraulic cylinder 52, rotating the plate 54 about the front bracket 57, thereby causing the roller 56 mounted on the plate 54 to move toward the pinching disc 41. The pinching force that the roller 56 applied to the cable 100 is thus proportional to the pressure of the fluid in hydraulic cylinder 52. The hydraulic cylinder 52 may be connected to an accumulator (not shown) so that the pinching force remains constant as the diameter of the cable 100 varies.
The manually adjustable roller assembly 60 operates in essentially the same manner as the hydraulically adjustable roller assembly 50. A turnbuckle 62 is used in place of the hydraulic cylinder 52 and piston shaft 53 to connect the triangular plates 54 to mounting bracket 58. Prior to operation, the turnbuckle 62 of the manually adjustable roller assembly is normally adjusted to deliver the approximate force desired to pinching disc 40. During operation, the precise pinching force desired may then be obtained by hydraulically adjusting the roller assembly 50.
The roller assemblies 50,60 are positioned on the housing 12 such that the roller 56 will contact the outer surface of the pinching disc 40,41 at a location corresponding to the position of the cable as shown in Fig. 2.
The cable pinching sheave 10 described above may be used in conjunction with devices known in the art for coiling or wrapping and stowing unused or retracted cable. Although the invention is described here for use with a cable, it may also be used with any flexible elongated member, including electrical and fluid conduits. It should therefore be understood that the word "cable" is used here in this broad sense.

Claims

1. A device for extending and/or retracting a cable, comprising:

a shaft coupled to a power source to rotate the shaft;

a substantially circular rim concentric with the shaft and positioned at a location radially outward from the shaft, the rim having a cable extending along a portion of its periphery;

rim support means coupling the rim to the shaft;

cable-engaging means positioned about each side of the cable; and

pushing means exerting an inward force on the engaging means, thereby pinching the cable between the engaging means to move the cable with rotation of the rim.

2. The device of claim 1 wherein the cable-engaging means are coupled to the shaft.

3. The device of claim 2 wherein the cable-engaging means comprise a disc concentric with the shaft positioned on each side of the rim, the outer edges of the discs extending radially from the shaft to a point beyond the rim and being biased inwardly toward each other against the cable by the pushing means.

4. The device of claim 3, further including weight reduction apertures in the discs.

5. The device of claim 2 wherein each cable-engaging means comprises an inner disc mounted on the shaft on opposite sides of the rim support means, an annular outer disc positioned concentric to the inner disc, and a resilient ring connecting the inner and outer discs such that the outer disc may pivot along the longitudinal axis of the shaft in response to the force applied by the pushing means.

6. The device of claim 5 wherein the inner disc terminates outwardly in a relatively narrow flange, the flange received within the resilient ring.

7. The device of claim 5 wherein the outer annular disc includes a relatively narrow flange projecting radially inward from the outer disc which is received within the resilient ring.

8. The device of claim 5, further including weight reduction apertures in the discs.

9. The device of claim 2 wherein the shaft has a plurality of longitudinal splines interlocking with the rim support means and cable-engaging means.

10. The device of claim 1 wherein the forces exerted by the pushing means have a component directed toward the longitudinal axis of the shaft.

11. The device of claim 1 wherein the portions of the cable-engaging means adjacent the cable are inclined inwardly such that the distance between the cable-engaging means de-. creases as the distance from the shaft increases so that when the inward force is applied to the inclined portion of the cable-engaging means, the cable-engaging means exerts a force on the cable having a component directed toward the longitudinal axis of the shaft.

12. The device of claim 1 wherein the rim support means consist of a circular metal plate having a relatively wide inner base interlocking with the shaft.

13. The device of claim 1 wherein the shaft has a plurality of longitudinal splines interlocking with the rim support means.

14. The device of claim 1 wherein the pushing means includes a roller positioned adjacent the cable-engaging means and further including means of exerting inward pressure on the roller.

15. The device of claim 1 wherein the pushing means are capable of exerting a variable force on the engaging means.

16. The device of claim 1 wherein the shaft has a plurality of longitudinal splines interlocking with the rim support means.

17. A device for extending and contracting a cable, comprising:

a splined shaft coupled to a power source to rotate the shaft;

a circular plate having a base mounted interlockingly on the shaft and an outer rim receiving a cable on its periphery_;

a pair of cable-engaging discs interlockingly mounted on the shaft, including an inner disc mounted on the shaft and having a diameter that is substantially smaller than the diameter of the circular plate; an outer annular disc positioned concentric with the inner disc, the outer surface of the outer disc extending to a location radially outward from the periphery of the rim; and a resilient ring connecting the inner and outer discs such that the outer disc may pivot along the longitudinal axis of the shaft;

a roller positioned adjacent the portion of each cable-engaging disc which extends outwardly beyond the rim such that when an inward force is applied to the roller, it will rollably engages the disc and pivots the outer discs inward toward a cable positioned on the periphery of the rim, thereby applying a pinching force to the cable; and

bias means for applying an inward force to each roller.

18. The device of claim 17 wherein said bias means is a hydraulic cylinder, said device further including an accumulator coupled to the hydraulic cylinder to permit a constant pinching force to be applied to the cable when the cable size increases or decreases.