GB2291944A

GB2291944A - A device for arresting the fall,or controlling the descent,of personnel or equipment

Info

Publication number: GB2291944A
Application number: GB9415634A
Authority: GB
Inventors: Giovanni Farina
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-08-03
Filing date: 1994-08-03
Publication date: 1996-02-07
Also published as: GB9415634D0

Abstract

A device for arresting the fall, or controlling the descent, of personnel or equipment comprises a rotary drum member 1 and a stationary member 22, one of the members including braking blocks B each of which is biased into engagement with a cooperating braking wall of the other member and creates a greater frictional force upon rotation of the drum member in one direction than in the other. Biasing may be acheived by springs 14 and/or weights acting under centrifugal forces, hydraulic or pneumatic pressure, or magnetism, and the biasing means may be adjustable. <IMAGE>

Description

SAFETY APPARATUS The invention relates to a safety apparatus and more particularly to a device useful for absorbing the energy of a fall thus arresting the subject (personnel or equipment) in a controlled manner or for controlling the rapid descent of a subject in an emergency or on a controlled basis. Devices of this purpose are known and they usually comprise of a rope drum and a braking component to cooperate with a brake disc or drum and a stationary component.

It is one object of this invention to provide a device for the purpose specified which is easier to assemble to a predetermined braking torque. It is another object of the invention to provide such a device which will provide substantially the same braking force even when used repeatedly.

According to one aspect of the invention there is provided a device for use in arresting a fall or controlling a descent, the device being connectable to one end of a descent rope or the like, the device comprising an assembly of a rotary drum member, a stationery member and an intermediate braking member, one of the members including a braking block the other including a cooperate braking wall, wherein the facing surfaces of the block and the wall are shaped so that relative movement between the block and the wall tends to increase the braking force.

Preferably the braking wall is arcuate and the facing wall of the braking block includes an arcuate portion extending in a circumferential direction.

The invention may be applied to devices in which the block face and the cooperating wall portion are arcuate or curved or to devices wherein they are generally straight or define an acute angle. It is an essential feature of the invention that by defining the contact faces there is an increase in braking force as relative movement takes place in one direction.

Preferably the device includes a force generating means to urge the block towards the wall. The element may be spring means; hydraulic pressure, pneumatic pressure; centrifugal forces; magnetism; or the like. Preferably the means is adjustable to compensate for any wear of the contact parts.

Preferably a block is present in a cavity therefor in a sector of a wall present on the respective member. Preferably the sector is generally L shaped having a shorter limb extending radially of the rotary member and a longer limb extending towards the rim of the member. Preferably the force generating element is located between the shorter limbs and the facing end of the block.

In order that the invention may be well understood it will now be described by way of example only with reference to the accompanying drawings, in which Figure 1 is a side elevation of one device of the invention, parts being cut away; Figure 2 is an exploded view of the device of Figure 1; Figure 3 is an elevation of the outer face of the middle disc shown in Figure 2; Figure 4A is an enlarged view and Figure 4B is an end elevation of an individual brake block shown in Figure 3 Figure 5 is another device of the invention; and Figure 6 is yet another device of the invention The same reference numerals are used to identify the same parts in the different embodiments.

The device of Figures 1 to 4 comprises a spool shaped drum 1 having side walls 2, 3 joined by a spindle 4. A rope R is attached at one end to the device in any known way. A coilspring, not shown, is housed in the socket defined by the outer shape of the side wall 3 for retraction when required. The outer side of the wall 2 includes a pawl 5 of the flyin or flyout type to cooperate with an internally configured cover plate, not shown. The device so far described is conventional and the specific features are not essential to this invention.

The outer face of the side wall 2 is shown best in Figure 3 from which it can be seen that an annular wall 8 is present and is split into six outer segments 9. Each segment defines a generally L shaped cavity 10 having a short limb 11 extending radially of the disc and a longer wall 12 running towards the rim 13 of the disc. One end of a compression spring 14 is received in a hole 15 in the wall of the shorter limb 11. The length, diameter and force of the spring and the inclination is selected according to the required braking torque. The spring acts against the shorter end wall 16 of a generally wedge shaped brake block B. The shape of the block B is shown in Figures 3, 4A and 4B from which it can be seen that the block is generally triangular as seen in side view and has the flat end wall 16 and the inclined corner 17 where it meets the longer side 18.The shorter end 19 of the triangular shape is straight. The inclined wall 20 comprises a flat portion 20A and an arcuate portion 20B which joins the end 19. A chamfer 21 is present along the upper edge. Each block B is received in a cavity 10. A brake dnrm 22 is present beyond the outer face of the disc 2. The drum is generally dished and has an annular wall 23 dimensioned so that when the drum 22 is superimposed on the disc 2 the wall 8 is received within the wall 23, with a slight clearance fit. Because the blocks B are urged outwardly by their associated springs 14, the outer edge of the blocks tend to contact the inner surface of the arcuate wall 23.The disc 2 has a through hole 24 in alignment with the cylinder 3, and the drum 22 has a larger hole 25 in axial alignment to receive an end plate 26; long bolts 27 pas through the plate 265, drum 22, disc 2, and into aligned holes in the cylinder 4 to hold the components together.

By selection of the spring 14, and the dimensioning of the brake blocks B relative to the wall 23 of the drum 22 it is possible to predetermine the braking force. The spring provides a relatively large contact force between the block and the facing wall, because of the geometry, in one rotational direction. Thus one can control the braking so that braking will be even and a person undergoing a fall will not be subjected to excessive peak loads while his fall is being arrested. In use, the braking force is generated by the interaction of engagement of opposed faces of each brake block B and the wall of the drum, which force includes a radial component because of the relatively long dimension of the block in the circumferential direction. As the brake blocks B are pulled in the direction of the rotation of the disc 2, the wedge shape tends to be urged harder against the wall 23 of the drum 22. The spring 14 initiates and augments the braking force by urging the blocks B towards the wall 23, at a relative acute angle.

In the embodiment of Figure 5, the blocks 16 are in the outer wall, not the inner. In the embodiment of Figure 6, the walls are generally parallel and straight and the block 16 is set at an angle as shown.

The spring force tends to compensate for any wear of the block with repeated use, so that one can achieve substantially the same braking force throughout the life of the device. The brake blocks may be made of any suitable material selected to reduce abrasion and to maintain the block integrity and shape. Typically the block will be a bonded mixture of hard particles, e.g. a FERODO type material, sintered block, a composite; a metal, or the like.

The invention is not limited to the embodiment shown. For example the brake blocks may be located in the wall of the drum. The number of blocks may vary, and they need not all be of the same size. The blocks may have more than one arcuate wall, and some blocks may face in opposite directions to others. The blocks may be multi-part. Weights may be present to replace or assist the spring when the device is used as a descent control. The parts may be held together using circlips, or the like.

The rope may be of textile or wire, chain, or any other material or combination of materials known for the purpose.

Claims

1. A device for use in arresting a fall or controlling a descent, the device being connectable to one end of a descent rope or the like elongate element, the device comprising an assembly of a rotary member, a stationery member and an intermediate braking member, one of the members including a braking block and the other including a cooperate braking wall, wherein the facing surfaces of the block and the wall are shaped so that rotation or relative motion of the member increases the braking force.

2. A device according to Claim 1, including means to urge the block towards the wall.

3. A device according to Claim 2, wherein the means to urge the braking block towards the cooperating braking wall is a force provided by spring means, hydraulic pressure, pneumatic pressure, centrifugal force, magnetism; or the like.

4. A device according to Claim 3, wherein the means is adjustable to compensate for any loss of contact surface area between the braking block and the cooperating wall.

5. A device according to Claim 2, 3 or 4 wherein the means to urge the block towards the braking wall is spring biased between an end wall of the block and the shorter wall of the cavity.

6. A device according to any preceding Claim wherein the braking wall is arcuate and the facing wall of the braking block includes an arcuate portion extending in a circumferential direction.

7. A device according to Claim 6 wherein the block is present in a cavity therefor in a sector of an annular wall present on the rotary member.

8. A device according to Claim 7, wherein the sector is generally L shaped having a shorter limb extending radially of the rotary member and a longer limb extending towards the rim of the member.

9. A device according to Claim 8 including a spring between the block and the shorter wall of the cavity.

10. A device according to any of Claims 1 to 6 wherein the braking blocks are present in an inner rotary member and contact an annular wall.

11. A device according to any of Claims wherein the blocks are present in an outer member and contact an inner contact wall.

12. A device according to any of Claims 1 to 5, wherein the facing walls are generally straight, and the block extends at an inclination to the axis in between.