GB2131921A

GB2131921A - Rope descending device

Info

Publication number: GB2131921A
Application number: GB08232928A
Authority: GB
Inventors: Anthony Robert Morgan
Original assignee: M K Ltd
Current assignee: M K Ltd
Priority date: 1982-11-18
Filing date: 1982-11-18
Publication date: 1984-06-27

Abstract

A hand operated device for controlling the descent of a person down a rope comprises a base plate 10 having a rotatable cam member 13 mounted thereon, said cam member 13 having a lever 15, and mounted on the plate 10 are guide members 16, 17, 18, 19 and a guard 21 which can be positioned over the guide members 16-19 after the rope 23 has been passed under the guide member 16, around the cam member 13 and engaged with the guide members 17-19. When a downward load is applied to the device the tensioning of the rope 23 causes the cam 13 to pivot in order to jam the rope between the cam 13 and guide member 17, movement of the lever 15 in a direction towards the guide members 17-19 causes the cam 13 to rotate to increase the gap and the device slips down the rope at a controlled rate and release of the lever 15 causes the cam to be rotated by the loop in the rope to again jam the rope between the cam 13 and the guide member 17. <IMAGE>

Description

SPECIFICATION Rope descending device This invention relates to a hand operated device for controlling the descent of a person down a rope.

According to the present invention there is provided a hand operated device for controlling the descent of a person down a rope, comprising a base plate, a cam rotatably connected to said base plate and around which a loop in a rope is passed in use of the device, a lever extending from the cam for rotating said cam, a first fixed guide member provided on said base plate for guiding the rope to the cam, a second fixed guide member provided on said base plate adjacent said cam and around which the rope is passed after leaving the cam, said cam being shaped such that when in use the tensioning of the rope causes the loop portion to rotate the cam to jam the rope between the cam and the second fixed guide member, rotation of the cam in the opposite direction increasing the gap between the cam and said second fixed guide member to allow the device to slip on the rope.

Preferably a further guide member or members are provided on the plate.

A guard member is preferably pivotably connected to the plate to cover the part of the rope which in use extends through the device.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a device according to the present invention with the guard member swung back, and Figure 2 is a view taken in the direction of arrow 2 indicated on Fig. 1 with the guard swung to a vertical position compared with the inclined position shown in Fig. 1.

The device comprises a plate 10 having a portion 11 which extends to one side and is substantially triangular as shown in Fig. 1.

Pivotably connected at 1 2 to one side of the portion 11 is a cam member 1 3 having a side flange 1 4 which is extended by a lever 1 5.

Fixed to the plate 10 and extending from one side face thereof are circular guide member 16, 17, 18 and 19. Pivotably connected to the upper guide member 1 6 is a guard member 20 which is substantially L-shaped in cross-section having a wall 21 which extends over the outer ends of guide members 16, 17, 18 and 19 and a wall 22 which extends over the edge of the plate 10 when in the operative position. In the drawings the guard member 20 is shown swung about its pivot to an inoperative position which enables the device to be connected to a rope 23.The guide members 1 7 and 1 8 are provided at their outer end with a recessed head portion 24 of a fixing bolt which serves to fix them to the plate 10 and the guide member 1 9 is provided at its outer end with a screw 25 having a head portion 26 which is knurled to enable it to be rotated by a persons fingers.

The wall 21 is provided along its free edge with recesses 27, 28 and 29. The recesses 27 and 28 receive the fixing bolts of the respective guide members 1 7 and 1 8 when the guard member 20 is swung to its operative position, the wall 21 then engaging under the head portion 24 and in this position the recess 29 receives the screw 25 and is heid in position by the head portion 26.

In positioning the device on the rope 23 the guard member 20 is swung to an inoperative position and a loop portion 23a is formed on the rope 23 and passed around the cam member 1 3 and the rope 23 is passed under the guide member 1 6. The part of the rope 23 extending from the cam member 1 3 is passed over the guide member 1 7. The rope 23 can be positioned in three different arrangements giving three different speeds of descent, namely a fast speed, a slow speed and an intermediate medium speed. For producing a fast speed of descent the rope 23 after passing over the guide member 1 7 extends vertically downwardly along the plate.

This is shown by the broken lines at A.

For producing a slow speed of descent the rope 23 after passing over the guide member 1 7 is passed over the guide member 1 8 as shown by the broken lines at B and for producing an intermediate medium speed of descent the rope 23 after passing over the guide member 1 7 is led between the guide members 1 8 and 1 9 as shown by the broken lines at C.

The bottom end of the plate 10 is provided with an aperture 30 for receiing a ring or shackle which connects the device to a harness worn by the user. When a downward load is applied to the device, i.e. when subjected to the weight of the user the rope 23 is tensioned and loop portion 23a of the rope 23 causes the cam 1 3 to pivot in order to reduce the gap between the cam 1 3 and the guide member 1 7 and the rope 23 is thus jammed between the cam 1 3 and the guide member 1 7. In order to descend down the rope the user by means of one hand moves the lever 1 5 in a direction towards the guide members and due to the shape of the cam 1 3 the gap increases allowing the device to slip down the rope at a speed determined by the friction applied to the rope 23 by the cam 1 3 and guide members acting on the rope 23.

Upon release of the handle 1 5 the tension in the loop portion 23a will always rotate the cam 1 3 to the jamming position. Therefore the device is self locking on the rope 23 when the handle 1 5 is released. The provision for having three different speeds of descent is useful when training a person to abseil.

Claims

1. A hand operated device for controlling the descent of a person down a rope, comprising a base plate, a cam rotatably connected to said base plate and around which a loop in a rope is passed in use of the device, a lever extending from the cam for rotating the cam, a first guide member provided on said base plate for guiding the rope to the cam, a second guide member provided on said base plate adjacent said cam and around which the rope is passed after leaving the cam, said cam being shaped such that in use tensioning of the rope causes the loop portion to rotate the cam to jam the rope between the cam and the second fixed guide member, rotation of the cam in the opposite direction by means of said handle increasing the gap between the cam and said second fixed guide member to allow the device to slip on the rope.

2. A device as claimed in claim 1, in which a third guide member and a fourth guide member are provided on said plate so that the rope can be selectively engaged with said guide members to provide for slow, intermediate and fast speeds of descent down the rope.

3. A device as claimed in claim 1 or claim 2, in which a guard is pivotably connected to the plate to cover the part of the rope which in use extends through the device.

4. A device as claimed in claim 3, including means for holding the guard in its operative position.

5. A device as claimed in any preceding claim, in which the plate is provided with an aperture for receiving an ring or shackle for connecting the device to a harness worn by the user.

6. A device as claimed in any preceding claim, in which the plate has a triangular portion extending from one edge on which the cam is mounted.

7. A hand operated device for controlling the descent of a person down a rope, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.