GB2024912A

GB2024912A - Adjustable rope gripper

Info

Publication number: GB2024912A
Application number: GB7828672A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-07-04
Filing date: 1978-07-04
Publication date: 1980-01-16
Also published as: GB2024912B

Abstract

A device for use in descending a rope 27, comprises a friction grip which can be fitted on to the rope at any point along the length of the rope without the need to thread the rope through the device. Downward load applied to the device, causes the device to lock on to the rope and prevent descent. The device has a control lever 15 which can be pulled down to reduce friction thereby bringing about a controlled descent. If the control member is released again, the device locks on to the rope and prevents further descent. <IMAGE>

Description

SPECIFICATION Descending devices The invention relates do descending devices and particularly to devices for use in descending a rope while engaged in climbing, potholing, or similar pursuits.

The invention provides a descending device for use in descending a rope, the device comprising a friction device which can be fitted on to a rope at any point along the length of the rope without the need to thread one end of the rope through the device, the device being such that if the device is fitted on to an upwardly extending rope and a downward load is applied to the device, friction causes the device to lock on to the rope and prevent descent, the device having a control member which can be urged by a user of the device in a direction to reduce the amount of friction thereby bringing about a controlled descent, but if the control member is released, the device locks on to the rope again and prevents further descent.

Preferably the device comprises a first member, a second member and a third member connected together to define an undulating path for the rope, the second member lying between the first and third members and being movable by the control member between a locking position in which the rope will be trapped between the second member and one of the first and third members, and a descending position in which the rope can slide along the undulating path.

Preferably the device has a pair of spaced-apart side members and the first and third members each extend from one side member to the other side member, the second member having a free end so that the device can be attached to a rope at any point along the length of the rope by forming a loop in the rope, passing the loop between the side members, and hooking the loop over the free end of the second member.

Preferably the free end of the second member projects beyond the side member adjacent to the free end, in such a manner as to reduce the risk of the loop of rope slipping off the second member.

Preferably the second member has a mounting which lies between the side members and which engages a central part of the second member, the second member thus having two free ends and the second member being longer than the width of the gap between the side members so that each free end projects beyond the adjacent side member.

The device can thus be used with a doubled rope by forming a loop in one rope, passing the loop between the side members and hooking that loop over one free end of the second member, and then forming a loop in the other rope, passing that rope between the side members and holding that loop over the other free end of the second member.

The second member can conveniently be mounted directly on the control member, the control member being pivotally mounted between the side members.

The control member may comprise a lever mounted for pivotal movement about an axis which coincides with the first member, such that movement of the lever to and fro causes movement of the second member towards and away from the third member.

The side members preferably comprise a pair of side plates.

The plates may project beyond the third member to form a mounting point for attaching a load to the device.

The plates may have a cut-away or recessed portion to increase the extent to which the second member can move towards the third member.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings in which: Figure 1 is a front view of the device, attached to a doubled rope; Figure 2 is a side view of the device, with one side plate removed for the sake of clarity, the device being shown in the locking position; Figure 3 is a view similar to Figure 2, but showing the device in the descending position; and Figure 4 is a side view of the control member.

The device shown in the drawings comprises a pair of parallel side plates 10 and 11 made of aluminium alloy. The plates are spaced apart by a first friction creating member 1 2 and a second friction creating member 1 3 extending between the plates. The member 12 comprises a pair of aluminium alloy collars 14. A lever 1 5 is sandwiched between the collars 1 4 and the side plates, collars and lever are all secured together by a bolt 1 6 which passes through all the items and has a nut 1 7 secured on the end thereof.

The member 1 3 comprises a cylindrical member of aluminium alloy which is held in position by a second bolt 1 8 and nut 19.

The cylindrical member 13 and the collar 14 are such that the bolts 16 and 18 are a tight fit within these items, preventing them from rotating.

Furthermore there is a spacer member (not visible in the drawings) threaded on to the bolt 1 6 between the collars 14 so that the collars can be tightly clamped by the nut and bolt without trapping the lever 1 5. The pivot hole 20 (see Figure 4) of the lever 1 5 is sufficiently large to ensure that the lever 1 5 can pivot freely about the spade member.

A second, central friction creating member 21 is mounted on the lever 1 5. This member comprises a pair of collars 22 mounted one at each side of the lever 1 5. A bolt 23 passes through one of the collars 22, then through a hole 24 (see Figure 4) in the lever 15, then through the other collar 22, and a nut 24 is finally secured to the free end of the bolt. The arrangement is such that the collars 22 cannot rotate about their axis.

As can be seen from Figure 1, the length of each collar 22 is such that the collar projects well beyond the adjacent side plate 10 or 11.

The plates 10 and 11 project beyond the friction creating member 1 3 and are then bent inwardly to meet one another at 25. A hole 26 is formed through each plate in the area where they meet, so that a load can be attached to the device, for example using a snap link.

If it is desired to use the device to descend a doubled rope, the device is first attached to the rope with the device arranged so that the end carrying the hoies 26 is lowermost. One strand 27 of the doubled rope is formed into a loop 28 and the loop is passed between the side plates 10 and and is hooked over one of the collars 22. A second loop 29 is formed in the other strand 30 of the rope end this loop is passed between the side plates, on the other side of the handle 1 5, and is hooked over the other collar 22. Botch strands of rope now follow an undulating path through the device, the strands of the rope engaging with all three friction creating members.The length of the collars 22 is such that once tension is applied to the rope, there is virtually no possibility of the loops 28 and 29 slipping off the collars 22 thereby detaching the device from the rope.

A person wishing to use the device clips a snap link to which he is attached into the holes 26, so that his body is suspended from the device. The load on the device causes the device to tend to slip down the rope. This in turn creates friction on the rope and the device is such that these frictional forces pull the collars 22 towards the member 1 3. The strands of rope are trapped between the collars 22 and the member 13, as shown in Figure 2, and the device locks on to the rope.

The handle 1 5 is in the form of a bellcrank lever, the dimensions of the lever and the positions of the holes 20 and 24 being such that downward pressure on the lever 1 5 urges the collars 22 away from the member 13, as shown in Figure 3. Thus when a user of the device wishes to descend, he merely applies downward pressure to the lever 15, to move the lever into the position shown in Figure 3. In this position the strands of rope are not trapped and the device slowly slides down the rope, the rate of descent being controlled as a result of the friction arising between the rope and the friction creating members.The rate of descent can be varied by adjusting the position of the handle 15, and if the user should accidentally let go of the handle 15, or become injured, he does not fall rapidly down the rope, as is the case if a climber or potholer loses control of a known descender. The device immediately locks into position, and the user is suspended safely from the rope.

The device shown in the drawings provides a simple, lightweight descending device with a minimum number of parts. It enables a user to fasten himself onto a rope at any point along the length of the rope and descend the rope safely, even if he loses control, for example as a result of becoming injured. X There is no need to control the position of the rope with the hands in order to ring about the necessary amount of friction, as is the case with many l.own descending techniques.

The device is particularly versatile in that it can be utilised on a single rope or a doubled rope.

When used with a single rope, the single rope is treated in exactly the same manner as one of the strands 27 or 30. In other words the rope is hooked around one of the collars 22 and the other collar 22 is not used.

It will be seen from Figure 3, that because of the bellcrank shape of the lever 15, the edge 31 of the handle is relatively close to the member 13.

This ensures that if the two strands of rope become twisted below the descending device, the risk of the twisted part of the rope becoming jammed in the descending device is reduced. As the two strands of rope approach the member 1 3 during a descent, the edge 31 of the handle 15 tends to separate the strands of the rope and remove any twist.

The invention is not restricted to the details of the foregoing embodiment. For example the portion of the lever 1 5 which is grasped by a hand of the user may be provided with a handgrip, for example of plastics or rubber material.

It is most important that the friction creating members do not rotate, since they would then cease to provide adequate friction, and if desired additional means may be provided to prevent these members from rotating. For example eccentrically mounted pins may be provided to pin the collars 14 and member 13 to the side plates, and to pin the collars 22 to the lever.

While the device shown in the drawings is particularly suitable for use in climbing and potholing, it may also have uses as a device for escaping from buildings or other high structures.

Furthermore the device can operate in the inverted condition. For example the device may be suspended from a fixed point using holes 26, a rope may be attached to the device, a load (e.g. an injured person or stretcher) may be secured to an end of the rope, and a person stationed at the fixed point may use the lever 1 5 to pay out the rope through the device in a controlled manner, thereby lowering the load.

Claims

1. A descending device for use in descending a rope, the device comprising a friction device which can be fitted on to a rope at any point along the length of the rope without the need to thread one end of the rope through the device, the device being such that if the device is fitted on to an upwardly extending rope and a downward load is applied to the device, friction causes the device to lock on to the rope and prevent descent, the device having a control member which can be urged by a user of the device in a direction to reduce the amount of friction thereby bringing about a controlled descent but if the control member is released, the device locks on to the rope again and prevents further descent.

2. A descending device as claimed in Claim 1, comprising a first member, a second member and a third member connected together to define an undulating path for the rope, the second member lying between the first and third members and being movable by the control member between a locking position in which the rope will be trapped between the second member and one of the first and third members, and a descending position in which the rope can slide along the undulating path.

3. A descending device as claimed in Claim 2, having a pair of spaced-apart side members, the first and third members each extending from one side member to the other side member, the second member having a free end so that the device can be attached to a rope at any point along the length of the rope by forming a loop in the rope, passing the loop between the side members, and hooking the loop over the free end of the second member.

4. A descending device as claimed in Claim 3, in which the free end of the second member projects beyond the side member adjacent to the free end, in such a manner as to reduce the risk of the loop of rope slipping off the second member.

5. A descending device as claimed in Claim 4, in which the second member has a mounting which lies between the side members and which engages a central part of the second member, the second member thus having two free ends and the second member being longer than the width of the gap between the side members so that each free end projects beyond the adjacent side member.

6. A descending device as claimed in any oneeof Claims 3 to 5, in which the second member is mounted directly on the control member, the control member being pivotally mounted between the side members.

7. A descending device as claimed in Claim 6, in which the control member comprises a lever mounted for pivotal movement about an axis which coincides with the first member, such that movement of the lever to and fro causes movement of the second member towards and away from the third member.

8. A descending device as claimed in any one of claims 3 to 7, in which the side members comprise a pair of side plates.

9. A descending device as claimed in Claim 8, in which the plates project beyond the third member to form a mounting point for attaching a load to the device.

1 0. A descending device as claimed in Claim 8 or Claim 9, in which the plates have a cut-away or recessed portion to increase the extent to which the second member can move towards the third member.

11. A descending device constructed and arranged substantially as herein described, with reference to the accompanying drawings.