GB2226071A

GB2226071A - Safety device for workmen

Info

Publication number: GB2226071A
Application number: GB8927488A
Authority: GB
Inventors: William Gibson Queen
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-12-15
Filing date: 1989-12-05
Publication date: 1990-06-20
Also published as: GB8927488D0; GB8829415D0

Abstract

A safety retaining device for personnel working on substantially vertical faces, especially on ladders, the device (1) is held in and runs in a conduit (2) for example a tube which can be positioned centrally on a ladder. The device (1) comprises a head (6) essentially of cam form to permit movement in the conduit when in a first position but prevent movement when in a second position to arrest a fall and the head is spring-biassed to either the first or, preferably, the second position. The head (6), mounted on stem (2), may be carried by a U-shaped holder member (9) to which a harness (18) can be joined and which has legs (12A, 12B) projecting through a slot (11) at the conduit (2) to guide the member. In the form shown, spring (16) biases the holder member (9) and head towards said first position. The holder member (9) preferably has rollers (not shown) for smooth movement in the freed condition. <IMAGE>

Description

"SAFETY RETAINING DEVICE FOR WORK PERSONNEL" Description The present invention relates to a safety retaining device for work personnel. It is the principal object of the present invention to provide a retaining device for work personnel which is runnable in vertical directions to enable work personnel to move safely on vertical faces eg on building fronts or chimneys but which arrests the fall of the personnel on the event of an accident.

According to the present invention a safety retaining device for work personnel comprises a head member runnable in a conduit, said head member being of cam form whereby the member runs in said conduit when orientated in a first position but is blocked for movement when orientated in a second position, a stem on said head member to extend through an axial slot in said conduit, holder means for a tethering device carried by said stem, and spring means for biasing the head member towards one of said first and second positions, preferably towards said second position.

Preferably the retaining device includes a leg portion spaced from the stem and adapted to extend into the conduit slot. Said spring means may be located on said leg portion. Preferably the tethering device holder means comprises a holder cup and the stem includes a second head portion having a spherical surface portion for nesting in said holder cup.

In a preferred embodiment, the holder means carries a runner member to facilitate movement on the conduit.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Fig 1 shows a side view of a safety retainer device according to the present invention in the biased locked position; Fig 2 shows a front view of the device, and Fig 3 shows similar view to Fig 1 but with the device in an unlocked moveable condition, while Figs 4A/B are end views corresponding to Figs 3/1.

Figs 5A - 5C show similar views to Figs 1 and 3 for further embodiment of the present invention; Fig 6 shows a front view of the device of Figs 5A 5C.

Referring to Figs 1 - 4 of the drawings, a safety retainer device 1 for work personnel is carried by a tube 2 intended for vertical orientation and in this example attached to the rungs 3 of a ladder fixed in the vertical wall 4 of a building, the tube 2 being positioned centrally on the rungs 3 (Fig 2). The device 1 comprises a runner member 5 having a first head 6 located in the tube 2, a stem 7 extending through an axial slot 11 in the tube 2 and a second head 8 on the stem 7, and a holder member 9 for a personnel tethering device 10 (Fig 1) is located by the head 8. The tube 2 can be similar to the tube shown in the personnel safety retainer described in the applicants UK Patent Application 8717724 (2193993). The holder member 9 comprises a U-bar 12 having leg portions 12A, 12B for location in the slot 11, and a cup 13 fixed (eg by welding) between the U-bar legs.The head 8 is of ballform and nests in a complimentary shaped recess 14 in the cup 13, the head 8 being screwed to the stem 7 whereby the holder member 9 can be fitted to the runner member 5 by inserting the stem 7 through a bore 15 in the base of the cup 13 and then screwing the ball head 8 onto the stem 7.

The head 6 is' formed as a cam structure such that when the head is orientated into a first position (Figs 3 and 4A) the runner 5 can move freely in the tube 2 but when moved to a second position (Figs 1, 4B) the head jams in the tube 2 to preclude runner movement. In particular, the head 6 is preferably formed from a cylindrical plug having a diameter D enabling it to slide in the tube 2. The end 6A of the plug is shaped substantially as a hemisphere while the other end 6B has a flat F1 cut at about 45 to the plug axis whereby there is formed two cam flats F1, F2. Further, side portions S at F1, F2 are curved to enable the head 6 to fit into the tube 2 with the plug axis transverse as shown.In the free position (Figs 3 and 4A) the head 6 has a width W in the direction of the tube diameter less than said diameter, while in the jammed position shown in Fig 1 and Fig 4B) edges J (Fig 4B) of the head 6 engage the tube inner wall to cause the head 6 to jam. The leg portions 12A, 12B assist in guiding the device 1, and a feature of the arrangement is that a compression spring 16 located on the leg portion 12A biases (tilts) the device 1 to the second locking position shown in Fig 1, the spring 16 being located between the cup 13 and a washer 17 abutting the tube 2. Hence, the device 1 automatically adopts the locked retaining position and this is conductive to safety.The spring tension is chosen such that the device 1 can be tilted upwardly to the released position shown in Fig 3 without undue force (ie per arrow F) but nevertheless for the device 1 to be returned promptly and effectively to the locked position when force F is removed: as will be appreciated spring tension can be varied conveniently by adjusting the position of the head 8 (and the cup 13) on the stem 7.

The device 1 does not project excessively from the plane of the ladder so that a work person using the latter can be comfortably positioned at the device 1.

As can be see in Fig 1, the harness 18 of the work person can be connected to the holder member 9 using only a short tethering piece 10 eg in the form of a releasable clip. This precludes excessive momentum build-up in the event of a fall, and the spherical contact between the runner ball head 8 and the holdercup 13 is well capable of handling high fall loads in which situation the runner member 5 is located in the second jammed non-moving position (Fig 1). The prompt arrestment of the runner member 5 by the action of spring 16 mitigates against momentum build-up which would occur if the member 5 were permitted to run down the tube 2 for a period prior to run down the tube 2 for a period prior to arrestment.

However there may be situations where it is preferred to have the device 1 biased to the release position (Fig 4) and this can be easily achieved by fitting the spring 16 (and washer 17) on the leg portion 12B.

Figs 5A - 5C show a further embodiment generally similar to that of Fig 1 and like parts carry like reference numerals but in this case the holder member 9 has a projection 9A supporting an axle 21 on which are rotatably mounted a pair of rollers 22, the rollers 22 being held in position by washers 23 and split pins 24.

When the retainer device is in the freed position (Fig 5A) the rollers 22 run on the tube 2 so enabling the device to run smoothly on the tube 2. Downward movement of the holder member 9 as in Fig 5C increases the jamming action. Further, in this example the spring 16 is located on the stem 7. The device 1 of Figs 5A - 5C operates similarly to that of Fig 1: in Figs 5B and 5C the device 1 is in the jammed arrested condition whereas in Fig 5A the holder member 9 has been tilted against.

the action of spring 16 to free the device 1 to permit movement along the tube 2.

As it is important the device 1 is fitted into the tube 2 the correct way round, appropriate markings I, I2 are included in the head 6 and holder member 9 respectively.

Claims

1. A safety retaining device for work personnel comprising a head member runnable in conduit, said head member being of cam form whereby the member runs in said conduit when orientated in a first position but is blocked for movement when orientated in a second position, a stem on said member to extend through an axial slot in said conduit, holder means for a tethering device carried by said stem, and spring means for biasing the head member towards one of said first and second positions.

2. A safety retaining device as claimed in claim 1, wherein the head member is biased towards said second position by the spring means.

3. A safety retaining device as claimed in claim 1 or 2, wherein the retaining device includes a leg portion spaced from the stem and adapted to extend into the conduit slot.

4. A safety retaining device as claimed in any one of the preceding claims, wherein the tethering device holder means comprises a holder cup and the stem includes a second head portion having a spherical surface portion for nesting in said holder cup.

5. A safety retaining device as claimed in any one of the preceding claims wherein adjusting means are provided for adjusting the tension setting of the spring means.

6. A safety retaining device as claimed in claim 5, wherein the spring adjusting means comprise means for adjusting the relative position of the stem and the holder means.

7. A safety retaining device as claimed in claim 6 when dependent on claim 4, wherein the spring adjustment means comprise means for varying the axial position of said second head member on the stem.

8. A safety retaining device as claimed in any one fo the preceding claims wherein the spring means are located on the stem.

9. A safety retaining device as claimed in claim 3, wherein the spring means are located on said leg portion.

10. A safety retaining device as claimed in any one of claims 1 to 8, wherein a runner member is provided to facilitate movement of the device on said conduit when the head member is in said first position.

11. A safety retaining device substantially as hereinbefore described with reference to and as illustrated in figs 1 to 4 or to Figs 5A-C and Fig 6 of the accompanying drawings.

12. A safety retaining device substantially as hereinbefore described with reference to and as illustrated in Figs. to 4 or to Figs. 5A to C and Fig.

6 of the accompanying drawings.