GB2304791A - Cable grip - Google Patents

Abstract

A cable grip for a load attachment system comprises a body 10 defining a cable bed adapted to receive a loop of cable, a releasable gripping member 20 operable between a cable release condition and a cable gripping condition, and operating means 40 for effecting movement of said gripping member 20 between said release and gripping conditions. Body 10 may have upstanding flanges 11, 13 with concave cable-engaging surfaces. The outer periphery of gripping member 20 may also be concave. Preferably, operating means 40 has an over-centre action to maintain the cable grip in the closed condition during use. Supplementary fastening means (140, not shown) may be provided to secure operating means 40 to the body 10 in order to minimise the risk of accidental release and/or to prevent tampering.

Description

CABLE GRIP The present invention relates to a device for gripping a flexible support member such as a cable or rope. In particular, the invention is concerned with a cable grip for use in load attachment systems in which a load attachment device is movable along an elongate support secured with respect to a fixed support structure.

A known load attachment system is described in British Patent No.

1,582,201. Here, a flexible elongate element such as a cable is fixedly secured at its ends to a support structure and is also supported at intermediate locations with respect to said structure. The system includes a load-transfer or traversing device which is either used to support the elongate element at each intermediate location, or is engaged with the elongate element to move along it with the ability to traverse the intermediate supports without detachment from the cable.

In such circumstances, the cable used for the elongate support is usually provided with end ferrules or sleeves swaged thereon, which features are provided with integral couplings for bolting to location fittings secured to the fixed structure.

Where the cable serves as a personnel safety line, a shock absorbing device may be incorporated between the cable end and the fixed support, as described in the applicant's European patent application number 0 605 538.

The present invention is concerned with the erection of such load attachment systems. It is an object of the invention to provide a cable grip which obviates the need to terminate the cable with end ferrules, swaged sleeves or similar cable terminations that require modification of the cable end.

It is a further object of the invention to provide a cable grip which is easy to engage and disengage from the cable to assist in the achievement of the desired degree of pre-tensioning during erection of a load attachment system.

The invention is a cable grip comprising: a body member defining a cable bed adapted to receive a loop of cable in use; a releasable gripping member operable between a cable release condition and a cable gripping condition, and operating means separate from said gripping member for effecting movement of said gripping member between said release and gripping conditions.

Preferably, the operating means for effecting movement of the gripping member between its cable release and cable gripping conditions comprises a lever pivoted to the body member at a first position and pivoted to a gripping member driving link at a second position. The gripping member driving link is, in turn, connected to the gripping member at a position remote from its pivotal connection to the lever.

Typically, the body member is a metal casting having a pair of up-turned flanges, the internal surfaces of which are concave in cross-section to serve as a cable seat. Preferably, the cable-engaging surfaces of the gripping member are similarly configured so that, when the device is in the fully closed condition, the trapped loop of cable is gripped snugly around most of its periphery. This helps to equalise loads throughout the gripped length of cable, thereby minimising local stresses.

Preferably, the lever operates with an over-centre action so that, when it is in the fully closed condition, the lever is prevented from being pulled round to its own open position by any tension in the cable.

Additionally, the lever may be provided with a hole for receipt of a padlock shackle. A complimentary hole provided in the body member or, if necessary, an upstanding projection from the body member, allows the lever to be padlocked to the body in order to prevent tampering or accidental release.

The invention will now be described by way of example only with reference to the drawings in which: Figure 1 is a front view of a device according to the present invention, shown in the fully open condition, and Figure 2 is a sectional side view of the device of Figure 1 shown in the fully closed condition.

Referring now to Figure 1, a cable grip in accordance with the present invention comprises a body member 10 having a pair of upstanding flange members 11, 13 which define a cable seat as described in more detail below.

A gripping member 20 is mounted on the body member 10 and is arranged to move in relation thereto between a cable-release condition and a cable-gripping condition. A gripping member driving link 30 is connected to gripping member 20 by means of pivot bolt 110 and penny washer 120.

An operating lever 40 is pivotally mounted on the body member 10 by means of pivot bolt and nut arrangement 90, 91. Lever 40 is, in turn, connected to driving link 30 by pivot pin 50.

The connection between gripping member 20 and operating lever 40 is indirect via driving link 30.

Referring now to Figure 2, the device of Figure 1 is here depicted in the fully closed condition, the principal features being shown in side sectional view.

In this view, it is possible to see more clearly the nature of the connection between gripping member 20 and driving link 30. Beneath penny washer 120, driving link 30 is formed with a large cut-out portion 31 into which an upstanding spigot 21 of the gripping member 20 projects. Spigot 21 is surrounded by a resilient bush 130 which is accommodated within the cutout portion 31. The purpose of resilient bush 130 will be explained in more detail below.

In the vicinity of the pivotal connection between body member 10 and operating lever 40, a spacer bush 60 surrounds the shank of pivot bolt 90 where it passes through slots in the driving link 30 and the gripping member 20. In this view, there is also shown an attachment link 70 journalled on pivot bolt 90, by means of which the cable grip device may be attached to a fixed structure or an intermediate, for example a shock absorbing apparatus as described in the Applicant's European Patent Application No. 0 605 538.

Operating lever 40 is arranged to have an over-centre action so that, when it is moved from the fully-open condition shown in Figure 1 to the fullyclosed condition shown in Figure 2, it passes a neutral or "top dead centre" position and remains biased to the closed condition. This is achieved in the illustrated embodiment by the reaction of the resilient bush 130 against the periphery of cut-out portion 31 of the driving link 30. The biasing pressure urges driving link 30 to the right in Figure 2. The driving link, in turn, exerts a turning force on operating lever 40, effective to keep it in abutment against a projection 12 of flange 11.

As shown, operating lever 40 is fixedly secured to projection 12 of flange 11 by means of a padlock 140, the shackle 141 of which passes through holes 41 and 1 2a of the lever and flange projection, respectively. The padlock 140 is an optional feature which minimises the risk of accidental release of the operating lever 40 and prevents tampering.

In Figure 2 it is also possible to see the preferred concave contour of flange 11 and the preferred concave outer periphery 22 of gripping member 20.

For reasons of clarity, Figure 2 does not show a captive cable in the cable seat.

However, the preferred concave contours described above are effective to facilitate a snug grip around much of the cable circumference so that local stresses are minimised.

As best seen in Figure 1, the flanges 11 and 13 are spaced apart but convergent. A gap 14 is provided between the flanges at the end of the body member 1 remote from the fixed structure (not shown). Gripping member 20 has an external profile which is complementary to the convergence of the flanges 11 and 13. At the end of gripping member 20 nearest the fixed structure (not shown), a part-circular profile 23 is provided so that an entrapped cable can form a natural loop without undue stresses being imposed.

In the embodiment described above with respect to Figures 1 and 2, it is important that the loaded length of cable is threaded around the device in the right orientation. To assist users in this respect, the respective flanges 11 and 13 of the body member 10 may be stamped with instructive labels such as "LOADED CABLE THIS SIDE" and "FREE SIDE", as appropriate.

To install the device on a length of cable, the cable grip is first fully opened by rotating the operating lever 40 fully in the clockwise direction (with reference to Figure 1). Preferably, it is held nearly horizontal whilst the cable to be anchored is inserted into the correct side of the device as indicated by the labelling on flanges 11, 13.

The operating lever 40 is then rotated fully in the counter-clockwise direction (in the sense of Figure 1) until it abuts projection 12 of flange 11.

It is only possible to effect full rotation of the operating lever 40 if the cable is properly seated in the device.

Having clamped a loop of cable in the device, the user may then partially release the operating lever 40 so that any undesired slack in the cable can be taken up by pulling on the cable free end. Then the operating lever is reengaged. Repetition of this step may be necessary until as much slack is removed from the system as possible. This is effective to achieve a first approximation of the desired pre-tension in the system. Accurate setting of cable tension must be achieved by other means, such rigging screws or turnbuckles incorporated elsewhere in the system.

Although the invention has been particularly described with reference to one preferred embodiment, it will be apparent to persons skilled in the art that other variants are possible without departing from the scope of the claims which follow.

Claims (10)

1. A cable grip comprising: a body member defining a cable bed adapted to receive a loop of cable in use; a releasable gripping member operable between a cable release condition and a cable gripping condition, and operating means separate from said gripping member for effecting movement of said gripping member between said release and gripping conditions.

2. A cable grip as claimed in claim 1 wherein said operating means comprises a lever pivoted to the body member at a first position and pivoted to a gripping member driving link at a second position.

3. A cable grip as claimed in claim 2 wherein said driving link is connected to the gripping member at a position remote from its pivotal connection to the lever.

4. A cable grip as claimed in any preceding claim wherein the body member has a pair of up-turned flanges serving as a cable seat.

5. A cable grip as claimed in claim 4 wherein the internal surfaces of said flanges are concave in cross-section.

6. A cable grip as claimed in claim 5 wherein the cable-engaging surfaces of the gripping member are concave in cross-section, the arrangement being such that, when the cable grip is in its fully-closed condition, the trapped loop of cable is gripped around much of its periphery.

7. A cable grip as claimed in any preceding claim wherein the operating means has an over-centre action so that, when the cable grip is in its fullyclosed condition, tension in the cable is ineffective to open the cable grip.

8. A cable grip as claimed in any preceding claim wherein supplementary fastening means are provided for releasably securing the operating means to the body member to prevent tampering or accidental release.

9. A cable grip substantially as described herein with reference to the drawings.

10. A load attachment system incorporating a cable grip as claimed in any one of the preceding claims.