GB2222629A

GB2222629A - A ladder/scaffold clamp

Info

Publication number: GB2222629A
Application number: GB8919619A
Authority: GB
Inventors: Brian Toomey
Original assignee: ABILITY INT
Current assignee: ABILITY INT
Priority date: 1988-09-09
Filing date: 1989-08-30
Publication date: 1990-03-14
Also published as: GB8919619D0; GB8821144D0

Abstract

A ladder clamp (2) for clamping a ladder (4) to a work tower (6), which ladder clamp (2) comprises first clamp means (8) for clamping to a stile (10) of the ladder (4), and second clamp means (12) for clamping to a horizontal brace (14) of the work tower (6), the first and the second clamp means (8, 12) being angularly offset from one another by an amount which allows the ladder (4) to be located in the work tower (6) at a safe working angle. Preferably the relative angle of the two clamping means is adjustable. <IMAGE>

Description

A LADDER CLAMP This invention relates to a ladder clamp and, more especially, this invention relates to a ladder clamp for clamping a ladder to a work tower.

Work towers are well known. They are self-supporting upstanding structures which are formed by connecting together scaffolding frames. The work towers are used in industry for enabling workmen to gain access to elevated work positions at which work is required to be done. The work towers can be built to various desired heights simply by varying the number of scaffolding frames that are mounted one on top of another.

Workmen using the work towers need to be able to climb easily up and down the work towers. Ladders are customarily provided in the work towers and there is a need for a device which enables a ladder easily and safely to be secured in a work tower.

It is an aim of the present invention to provide a device which satisfies the above mentioned demand.

Accordingly, this invention provides a ladder clamp for clamping a ladder to a work tower, which ladder clamp comprises first clamp means for clamping to a stile of the ladder, and second clamp means for clamping to a horizontal brace of the work tower, the first and the second clamp means being angularly offset from one another by an amount that allows the ladder to be located in the work tower at a safe working angle.

Preferably, the first and the second clamp means are angularly offset by an amount that allows the ladder to be set at a safe working angle of 150 to the vertical.

The first and the second clamp means can be angularly offset by any desired amount, for example to allow the ladder to be set up to a working angle of 450 to the vertical. The first and the second clamp means can be fixed to define a fixed angle of offset. Alternatively, the first and the second clamp means can be relatively movable to define an adjustable angle of offset.

The first clamp means may be a two part clamp comprising first and second clamp parts and screw threaded fastener means for tightening the first and the second clamp parts on the stile of the ladder. The screw threaded fastener means may be a bolt and an internally threaded bar which screws along the bolt.

The second clamp means may be a locking hook.

Preferably, the locking hook is as disclosed in our United Kingdom patent application No. 8808965.

If desired, the first and the second clamp means may be the same or different. Other types of first and second clamps to those described above may be employed if desired.

Preferably, the ladder clamp is made of a metal such for example as aluminium or an aluminium alloy.

An embodiment of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows a ladder clamp in operation clamping part of a ladder to part of a work tower; and Figure 2 shows the ladder clamp of Figure 1 and illustrates in more detail the ladder and the work tower.

Referring to Figures 1 and 2, there is shown a ladder clamp 2 for clamping a ladder 4 to a work tower 6.

The ladder clamp 2 comprises first clamp means 8 for clamping to a stile 10 of the ladder, and second clamp means 12 for clamping to a horizontal brace 14 of the work tower 6. The first and the second clamp means 8,12 are angularly offset from one another by an amount that allows the ladder 4 to be located as shown in the work tower 6 at a safe working angle. An example of a safe working angle for the ladder 4 is 15O to the vertical.

The first clamp means 8 is a two part clamp comprising a first clamp part 16 and a second clamp part 18. The first and the second clamp parts 16, 18 each have a hooked portion 20 for locating around the stile 10 and a straight portion 22. The two straight portions 22 are apertured so that screw threaded fastener means in the form of a bolt 24 is able to pass through the straight portions 22. A centre member 26 is also apertured and the bolt 24 also passes through the centre member 26.

The screw threaded fastener means includes an internally screw threaded bar 28 which locates as shown on the bolt 24 and which can be screwed along the bolt 24 to cause the hooked portion 20 to tighten around the stile 10.

The second clamp means 12 is a locking hook having a hooked portion 30 for fitting over the horizontal brace 14, and a strengthening web 32 to help to prevent deformation of the hooked portion 30 in the event that the ladder clamp 2 should be dropped from a height. The second clamp means 12 is as described in our United Kingdom patent specification No. 8808965, the disclosure of which is incorporated herein by reference. In particular, the second clamp means 12 has a body portion 33 and a locking member 35 which is movable between the locking and non-locking positions and which together with the hooked portion 30 defines a tube-receiving aperture for receiving the horizontal brace 14 which, as shown, of circular cross section.Also as shown, the horizontal brace 14 is provided with longitudinally extending ridges 34 which enable the outside of the horizontal brace 14 very securely to be gripped. The second clamp means 12 also has first and second abutment members (not shown) which are on the body portion 33 and which cooperate with a track (not shown) in the locking member 35. The track and the first and the second abutment members respectively control the movement of the locking member 35 as is described in detail in our United Kingdom patent application No. 8808965. Also as described in the United Kingdom patent application, the second clamp means 12 has biasing means in the form of a coil spring (not shown) for biasing the locking member away from the second abutment means.

The second clamp means 12 includes auxiliary locking means in the form of a grub screw.36. The grub screw 36 is for locking the locking member 35 in its locking position so that the second clamp means 12 cannot be then pulled off the horizontal brace 14 simply by squeezing the locking member in a manner which would otherwise release the locking member.

The first clamp means 8 is welded to a spacer tube 38 by a weld 40. The second clamp means 12 is welded to the spacer tube 38 by a weld 42. As indicated above, the first clamp means 8 and the second clamp means 12 are angularly offset from one another by an amount that allows the ladder 4 to be located in the work tower 6 at the illustrated safe working angle. This working angle may be the angle between first and second notional centre lines 44, 46, the first notional centre line 44 extending through the longitudinal centre of the first clamp means 8 and on to the spacer tube 38, and the second notional centre line 46 extending through the longitudinal centre of the second clamp means 12 and on to the spacer tube 38.

The spacer tube 38 is fixed to the hook and clamp by welds 40, 42. The spacer tube 38 can also be connected in a way that the angle of offset need not be fixed, i.e.

this joint can be achieved by the use of a pinned joint to enable the hook member 12 to pivot with respect to the clamp member 26 which would allow the tube 34 to be variously disposed at an angle to the ladder stile 10.

As shown in Figure 2, the ladder 4 is inclined inside a work tower 6. The ladder 4 comprises a base section 48 and an extension section 50. The base section 48 rests on a platform board 42. The work tower 6 comprises a plurality of scaffolding frames 54 mounted on top of each other as shown. The various scaffolding frames 54 are braced by diagonal braces 56. The horizontal brace 14 gives extra rigidity to the base of the work tower 6 and, with the ladder clamp 2 secured to the horizontal brace 14, the ladder 4 is prevented from moving sideways and backwards and forwards during use.

The upper end of the extension section 50 of the ladder is provided with a simple hook 58 which hooks over a horizontal frame member 60 of one of the scaffolding frames 54.

As shown, the work tower 6 is provided with an elevated platform board 62 and this platform board 62 is provided with a hatch door 64 through which a workman can climb, via the ladder 4 to gain access to the platform board 62.

The work tower 6 is provided with screw threaded extension legs 66 which are mounted on wheels 68.

In use of the ladder clamp 2, the ladder 4 can be slid to any desired height at any desired working angle by sliding the extension 50 of the ladder up or down as required in slides 70. The hook 58, which is simply secured by screws or rivets 72 to the extension section 50, is then located on an appropriate horizontal frame member 60. With the base section 48 of the ladder 4 resting on the platform board 52, the second clamp means 12 can easily and quickly be located on the horizontal brace 14. The ladder 4 will then be very securely held in position.

It is to be appreciated that the embodiment of the invention described above with reference to the accompanying drawings has been given by way of example only and that modifications may be effected. Thus, for example the first and the second clamp means 8,12 may be different from those illustrated. Also, the spacer tube 38 may be longer or shorter than shown and it may be of solid material if desired. Although the ladder 4 is shown as having circular cross section rungs 74, flat rungs may be employed. The rungs of the ladder may be ridged as shown to provide a good grip or they may be plain.

Claims

1. A ladder clamp for clamping a ladder to a work tower, which ladder clamp comprises first clamp means for clamping to a stile of the ladder, and second clamp means for clamping to a horizontal brace of the work tower, the first and the second clamp means being angularly offset from one another by an amount that allows the ladder to be located in the work tower at a safe working angle.

2. A ladder clamp according to claim 1 in which the first and the second clamp means are angularly offset by an amount that allows the ladder to be set at a safe working angle of 150 to the vertical.

3. A ladder clamp according to claim 1 or claim 2 in which the first and the second clamp means are fixed to define a fixed angle of offset.

4. A ladder clamp according to claim 1 or claim 2 in which the first and the second clamp means are relatively movable to define an adjustable angle of offset.

5. A ladder clamp according to any one of the preceding claims in which the first clamp means is a two part clamp comprising first and second clamp parts and screw threaded fastener means for tightening the first and the second clamp parts on the style of the ladder.

6. A ladder clamp according to claim 5 in which the screw threaded fastener means is a bolt and an internally threaded bar which screws'along the bolt.

7. A ladder clamp according to any one of the preceding claims in which the second clamp means is a locking hook.

8. A ladder clamp for clamping a ladder to a work tower, substantially as herein described with reference to the accompanying drawings.