GB2134065A - Safety line - Google Patents

Abstract

A safety line 6 for use by operatives working at a height, in which the line is secured to a fixture and is maintained in tension by a spring drum 2 as the operative moves around towards and away from the fixture, and wherein a lock mechanism 7 allows passage of the line in response to normal movement of the operative but is actuated to lock the line against extension on the application of tension in the line above a predetermined level equivalent to the effect of the operative falling. <IMAGE>

Description

SPECIFICATION Safety line This invention relates to apparatus for use as a safety line.

Men working on roofs have, due to the high risk of falls, to be provided with a safety line. To maximise the effectiveness of these safety lines it is preferable that they are kept substantially taut as the man moves around the roof, thereby minimising the distance that the workman may fall before being supported by the line.

Hitherto this meant that either a safety line had to be directly tied to a fixture on the roof and adjusted every time the workman changed position or a second man had to be employed to hold the length of line.

According to the present invention there is provided an extensible line one end of which is adapted for attachment to.a fixture, the line having means for attachment to a load to be restrained and a lock mechanism for the line actuable on an increase in tension in the line above a predetermined value.

The lock mechanism is preferably on the line intermediate said one end of the load.

Preferably, said lock mechanism includes a spring-loaded cam which locks the line, so as to prevent extension, when the tension in the line exceeds said value.

Preferably also, there is included a rope drum adjacent the lock mechanism provided with a recoil mechanism which rotates the drum so as to take up any slack in the line.

Embodiments of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of one embodiment of safety line apparatus in accordance with the present invention; Fig. 2 is a perspective view of the apparatus of Fig. 1 with one side of the casing removed; Fig. 3 is a side view of the apparatus of Fig. 1 showing details of the locking mechanism; Fig. 4 is an end view of the apparatus of Fig. 1 showing details of the rope drum; and Fig. 5 is a side view of the apparatus of Fig. 1 showing details of the axle assembly.

Referring to the drawings, safety line apparatus comprises a casing 1 having bolted sections 1A and 1 B and an attachment eye 1 C. A rope drum 2, for a rope 6 is mounted on an axle 3 which is rotatably mounted in the casing 1 and held against axial movement by circlip 4 fitted in grooves 3A (Fig. 5). The drum 2 is tensioned by a coil spring 5 which acts against a catch 3B on the axle 3. The rope 6 passes from the rope drum 2 through an inertia locking mechanism 7 before exiting from the casing 1 through an aperture 8.

The locking mechanism 7 comprises a backplate 9, rope guides 10, 11 and 12, rope pulleys 13, 14, a rope locking plate 1 5 and a rope locking cam 1 6 which is slidably mounted on the backplate 9 by way of guide pins 1 8 and held away from the locking plate 1 5 by springs 1 7.

The coil spring 5 is tensioned such that when out of use the length of rope 6 is retracted into the casing 1 and wound round the rope drum 2.

In use the apparatus is attached to a fixture by way of the eye 1 C and the rope 6 is pulled slowly out through the aperture 8 to be attached to a workman via a harness or the like. The person is then free to move about. Any slackness in the rope is taken up by the tension in the coil spring 5 causing the rope drum 2 to rotate and hence reel in the rope 6. Similarly if the person requires more rope he may exert sufficient pull on the rope to overcome the tension in the coil spring 5 thus causing the rope 6 to unwind from the drum 2 and pass through the locking mechanism 7.

In this case the pull on the rope 6 is insufficient to compress the springs 1 7 and therefore the locking cam 1 6 remains in position thus allowing the rope 6 to pass freely between the cam 1 6 and the locking plate 1 5. Should the person now slip, the sudden increased pull on the rope 6 will be such that the pull of the rope against the cam 1 6 will be sufficient to compress the springs 1 7 hence causing the cam 1 6 to slide, on the guide pins 1 8 towards the locking plate 1 5. Thus the rope 6 is gripped tightly between the cam 1 6 and the plate 1 5 such that further movement of the rope 6 is prevented hence arresting the fall of the workman.

Modifications and improvements may be made without departing from the scope of the invention.

1. A safety line between a fixture and a body moving towards and away from the fixture, the line having one end secured to the fixture and the other end secured to the body, traction means maintaining a low level of tension in the line, and a lock mechanism between the ends of the line, the lock mechanism allowing extension of the line, at a level of tension in the line below a predetermined value and locking the line against extension on application of tension in the line above said predetermined value.

2. A safety line according to Claim 1 , wherein the lock mechanism includes a spring-loaded cam which engages the line to prevent its extension on application of tension in the line above said predetermined value.

3. A safety line according to Claim 2, wherein the cam is movable between a first position towards which it is spring-loaded and in which the line passes freely around it and a second position in which it clamps the line against movement relative to the cam.

4. A safety line according to Claim 1, 2 or 3, wherein the traction means incorporated a winding mechanism for storage of the line prior to its extension.

5. A safety line according to Claim 4, wherein the traction means includes a coil spring which maintains the low level of tension in the line.

6. A safety line according to any one of the preceding Claims, wherein the traction means and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Safety line This invention relates to apparatus for use as a safety line. Men working on roofs have, due to the high risk of falls, to be provided with a safety line. To maximise the effectiveness of these safety lines it is preferable that they are kept substantially taut as the man moves around the roof, thereby minimising the distance that the workman may fall before being supported by the line. Hitherto this meant that either a safety line had to be directly tied to a fixture on the roof and adjusted every time the workman changed position or a second man had to be employed to hold the length of line. According to the present invention there is provided an extensible line one end of which is adapted for attachment to.a fixture, the line having means for attachment to a load to be restrained and a lock mechanism for the line actuable on an increase in tension in the line above a predetermined value. The lock mechanism is preferably on the line intermediate said one end of the load. Preferably, said lock mechanism includes a spring-loaded cam which locks the line, so as to prevent extension, when the tension in the line exceeds said value. Preferably also, there is included a rope drum adjacent the lock mechanism provided with a recoil mechanism which rotates the drum so as to take up any slack in the line. Embodiments of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of one embodiment of safety line apparatus in accordance with the present invention; Fig. 2 is a perspective view of the apparatus of Fig. 1 with one side of the casing removed; Fig. 3 is a side view of the apparatus of Fig. 1 showing details of the locking mechanism; Fig. 4 is an end view of the apparatus of Fig. 1 showing details of the rope drum; and Fig. 5 is a side view of the apparatus of Fig. 1 showing details of the axle assembly. Referring to the drawings, safety line apparatus comprises a casing 1 having bolted sections 1A and 1 B and an attachment eye 1 C. A rope drum 2, for a rope 6 is mounted on an axle 3 which is rotatably mounted in the casing 1 and held against axial movement by circlip 4 fitted in grooves 3A (Fig. 5). The drum 2 is tensioned by a coil spring 5 which acts against a catch 3B on the axle 3. The rope 6 passes from the rope drum 2 through an inertia locking mechanism 7 before exiting from the casing 1 through an aperture 8. The locking mechanism 7 comprises a backplate 9, rope guides 10, 11 and 12, rope pulleys 13, 14, a rope locking plate 1 5 and a rope locking cam 1 6 which is slidably mounted on the backplate 9 by way of guide pins 1 8 and held away from the locking plate 1 5 by springs 1 7. The coil spring 5 is tensioned such that when out of use the length of rope 6 is retracted into the casing 1 and wound round the rope drum 2. In use the apparatus is attached to a fixture by way of the eye 1 C and the rope 6 is pulled slowly out through the aperture 8 to be attached to a workman via a harness or the like. The person is then free to move about. Any slackness in the rope is taken up by the tension in the coil spring 5 causing the rope drum 2 to rotate and hence reel in the rope 6. Similarly if the person requires more rope he may exert sufficient pull on the rope to overcome the tension in the coil spring 5 thus causing the rope 6 to unwind from the drum 2 and pass through the locking mechanism 7. In this case the pull on the rope 6 is insufficient to compress the springs 1 7 and therefore the locking cam 1 6 remains in position thus allowing the rope 6 to pass freely between the cam 1 6 and the locking plate 1 5. Should the person now slip, the sudden increased pull on the rope 6 will be such that the pull of the rope against the cam 1 6 will be sufficient to compress the springs 1 7 hence causing the cam 1 6 to slide, on the guide pins 1 8 towards the locking plate 1 5. Thus the rope 6 is gripped tightly between the cam 1 6 and the plate 1 5 such that further movement of the rope 6 is prevented hence arresting the fall of the workman. Modifications and improvements may be made without departing from the scope of the invention. CLAIMS

1. A safety line between a fixture and a body moving towards and away from the fixture, the line having one end secured to the fixture and the other end secured to the body, traction means maintaining a low level of tension in the line, and a lock mechanism between the ends of the line, the lock mechanism allowing extension of the line, at a level of tension in the line below a predetermined value and locking the line against extension on application of tension in the line above said predetermined value.

2. A safety line according to Claim 1 , wherein the lock mechanism includes a spring-loaded cam which engages the line to prevent its extension on application of tension in the line above said predetermined value.

3. A safety line according to Claim 2, wherein the cam is movable between a first position towards which it is spring-loaded and in which the line passes freely around it and a second position in which it clamps the line against movement relative to the cam.

4. A safety line according to Claim 1, 2 or 3, wherein the traction means incorporated a winding mechanism for storage of the line prior to its extension.

5. A safety line according to Claim 4, wherein the traction means includes a coil spring which maintains the low level of tension in the line.

6. A safety line according to any one of the preceding Claims, wherein the traction means and the lock mechanism are contained within a common housing which is releasably secured to the fixture.

7. A safety line substantially as hereinbefore described with reference to and as shown in the accompanying drawings.