WO2008088268A1

WO2008088268A1 - Ladder with two side legs and an extension leg to bepressed against ground

Info

Publication number: WO2008088268A1
Application number: PCT/SE2008/000025
Authority: WO
Inventors: Jan Wallenius
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-01-16
Filing date: 2008-01-14
Publication date: 2008-07-24
Anticipated expiration: 2009-07-16
Also published as: SE0700080L; EP2115263A1; WO2008088268A8; SE529879C2

Abstract

The invention relates to a ladder with two side legs (1,2) and at the foot end of one of the side legs ( 2 ) an extension leg ( 5 ), which is slidably mounted in a holding device ( 4 ) attached to said one side leg ( 2 ), which holding device is provided with a locking device (13) that prevents a sliding downwards of the one side leg when the ladder is loaded, and a manually operated release device for permitting adjustment of the extension leg ( 5 ). The locking device is, according to the invention, designed to lock the extension leg (5) in both directions, and the extension leg is provided with a device (6) for detachable interconnection with a lateral tilt protecting device (9), which further is provided with a device (10,11) for detachable interconnection with the foot end of the other side leg (1).

Description

LADDER WITH TWO SIDE LEGS AND AN EXTENSION LEG TO BE PRESSED AGAINST GROUND.

The present invention relates to a ladder with two side legs and a number of runges extending between the side legs, and at the foot end of one of the side legs an extension leg with an anti-skid device to be pressed against a supporting surface, which extension leg is slidably mounted in a holding device fixedly attached to said one side leg, which holding device is provided with a locking device that prevents sliding downwards of the one side leg when the ladder is loaded, and a manually operated release device for permitting adjustment of the extension leg.

Such a ladder is known e.g. by the US patent No. 4,766,976, published in year 1988 , which discloses a locking device with a number of locking rings stacked on the extension leg, which locking rings by a compression spring are urged in oblique, self-locking position against a protrusion when the extension leg is pressed upwards in relation to the side leg at loading of the ladder. The locking device is released by pressing a finger against the upper edge part of the locking rings, such that the extension leg may be adjusted in relation to a possible laterally inclined ground surface, after which the locking device is actuated by removing the finger from the locking rings. Hence, the ladder can be used on uneven ground and on steps, but it cannot be equipped with a lateral tilt protecting device in the shape of a cross beam lying on the ground and attached to the foot ends of the extension leg and the other side leg, because the locking rings will be free to slide and permit tilting of the ladder over the side leg having its foot end attached directly to the lateral tilt protecting device. A functioning like that is prevented by using a ladder, later suggested and described in the Swedish patent SE 0600756-1. This ladder has side legs which both are equipped with slidable extension legs provided with locking devices as described above and mutually interconnected by a flexible connection running in a path along the side legs and between the side legs permitting the extension legs to move in opposite directions a decided maximal distance and brings about a locking of both the locking devices in the manner described above when a tightening occurs of the flexible connection when both the extension legs are pressed at the same time against a supporting surface. The ladder is characterized in that both the locking devices further are equipped with at least one further locking ring, which is adapted to lock in the opposite direction in relation to the first locking rings and simultaneously with the first locking rings be pressed in locking^' direction when the extension legs are pressed against a surface. Those foot ends are detachably connected with a lateral tilt protecting device in the shape of a cross-beam, which accordingly can transmit the load of the ladder to the support surface, which may be the ground or a staircase landing etc.

A ladder of this type can be utilized with or without the lateral tilt protecting device, and in the former case tilting is prevented in both directions due to the fact that both extension legs are fixedly secured against pushing as well as pulling forces. The construction with the flexible interconnection between the extension legs and the carefully adjusted connection with the locking devices in order to achieve locking of the two systems of locking rings in the two locking devices when the lateral tilt protecting device is set down on the support results in a ladder that is complicated to manufacture and to put together, and as a consequence unsuitably expensive.

The object of the invention is to achieve a ladder of the kind mentioned by way of introduction above, which can be equipped with a lateral tilt protecting device, and which is substantially easier and cheaper to manufacture and maintain than the previously known ladders.

This is obtained according to the invention in that the locking device attached to the said one side leg is designed to lock the extension leg in both directions, and that the extension leg is provided with a device for detachable interconnection with a lateral tilt protecting device, which further is provided with a device for detachable interconnection with the foot end of the other side leg.

In this way, the demand for the arrangement of two slidable and mutually interconnected extension legs has been eliminated as well as the demand for a reliable locking of two extension legs when the ladder is set downon a support. The ladder according to the invention has only one slidably journalled extension leg, and this extension leg is normally locked to the side leg in a reliable way by a locking device, which is manually released only when the position of the extension leg has to be adjusted.

The locking device may be of some known kind, e.g. in the shape ofa series of notches along the extension leg, and perpendicular to those a latch bolt journalled in the holding device and pressed by a spring into a hatch positioned in line with the latch bolt, which can be pulled-out a bit for permitting the extension leg to be adjusted. The locking device is preferably, however, designed according to claim 2 with a pair of V- positioned locking rings, which are slidably mounted on the extension leg and are positioned between two stop surfaces of the holding device, which stop surfaces engage the outside surfaces of the pair of locking rings at the closest to each other positioned edge portions, and the pair of locking rings are spaced apart by a compression spring between the pair of locking rings. This makes it possible to obtain a stepless adjustment of the extension leg after releasing the locking device by manual compression a bit of the locking rings spaced apart by the compression spring. If the anti-skid devic is unsuitable for interconnection with the lateral tilt protecting device it is possible to provide the opposite end of the extension leg with means for interconnection with the lateral tilt protecting device, in which case the extension leg or the holding device together with the extension leg is pivotal 180° for change between on one hand the use of the anti-skid device and on the other hand interconnection with the lateral tilt protecting device.

In case of a considerable incline of a support surface the extension leg protrudes a distance which may correspond to two normal steps of a staircase. Hence, it is important that the protruding end of the extension leg does not come to be exposed to bending stress at the inclining of the lateral tilt protecting device. Therefore, according to e preferred embodiment of the invention, either of the extension leg mounted on one of the side legs or the foot end of the other side leg is equipped with a control pin directed perpendicular to the lateral tilt protecting device, which control pin is journalled slidable in an arched control slit extending in the same direction as the lateral tilt protecting device in a bracket attached to the lateral tilt protecting device. The control slit has a guide surface with such a curvature that at all positions of the lateral tilt protecting device in relation to the ladder the control pin engages a part of the guide surface that is perpendicular to the push or pull direction of the control pin.

The invention is more closely clarified in the following with reference to the attached drawings, which show schematically various embodiments, chosen by way of example, of ladders according to the invention, and in which

Figure Ia and b is a front view of a ladder with mounted lateral tilt protecting device,

Figure 2a and b is a view of two sides of an extension leg in the position shown in Fig.Ib,

Figure 3a and b is a view from two sides of the extension leg shown in Fig.2a and b, after pivoting 180°,

Figure 4a and b is a front view of a ladder equipped with a mounted lateral tilt protecting device of a different design, and

Figure 5a and b is the same view as shown in Fig. 4a and b of an example of a further embodiment of a mounted lateral tilt protecting device.

The ladder shown in Fig.Ia has two side legs 1,2 connected by a number of rungs 3. A holding device 4 is attached to one of the side legs 2, in which holding device an extension leg 5 is slidably journalled in parallel with the side leg 2. The lower end of the extension leg 5 is connected by a bolt 6 with one end of a link 7. The other end of the link is by a bolt 8 connected with a lateral tilt protecting device 9 in the shape of a cross-beam. The lower end of the other side leg 1 is connected with the lateral tilt protecting device 9 by a fork-shaped coupling link 10, which by a coupling bolt 11 is attached to the lateral tilt protecting device 9 and with a part is inserted into the end of the side leg 1 and is secured to it by a bolt 12. The ladder is placed on a support surface sloping to the right in the drawing, and after release of a locking device 13 the extension leg 5 has slided down to the position shown, after which the locking device has been activated. The ladder has only one extension leg 5, so if the support surface should slope to the left in the drawing it is sufficient to turn the ladder half a turn. Hence, a second extension leg is unneeded. Fig. 2a and b discloses the extension leg 5 with associated holding device 4 and locking device 13. The holding device is a steel band, which has been bent backwards and forwars such that three parts are formed in which apertures 14 are made corresponding to the cross section of the extension leg 5. The extension leg 5 has been introduced down through the two upper apertures of the holding device, after which the locking device 13 consisting of a pair of three V-shaped locking rings 15,16 with an intermediate compression spring 17 has been slided onto the lower end of the extension leg 5 at the same time as said lower end is displaced downwards and inserted into the lowermost aperture 14. The holding device 4 has two corner parts 21 forming contact surfaces for the locking rings 15,16 such that the locking rings are kept in V-shape position under the influence of the compression spring 17, which has a pressure force adapted to keep the extension leg 5 in self-locking condition in the upward direction by the locking rings 15 and in the downward direction by the locking rings 16. In order to release the locking device it is necessary to press together the parts of the locking rings a bit which are diametrically opposed the parts of the locking rings that are actuated by the corner parts. This is easily made by using thumb and forefinger. Then when the locking rings are released the locking device is activated.

As disclosed by Fig.Ia the extension leg 5 is provided with the bolt 6 for connecting the extension leg with the lateral tilt protecting device 9. The opposed end of the extension leg is provided with a wobbly mounted anti-skid device 18, which makes it possible, after pivoting the extension leg 180°, to use the ladder without a lateral tilt protecting device 9.

The holding device 4 is attached to the side leg 2 by two bolts 19,20. If the ladder is to be placed on a support surface on which a lateral tilt protecting device is unusable, for instance a staircase, it is possible to ease off a the bolts 19,20 and after pivoting the holding device together with the extension leg 180° to be secured again in the existing holes in the side leg 2, as shown in Figs. 3a and b,

Figs.4a and b show an embodiment similar to the embodiment shown in Figs.Ia and b with the difference that the link 7 in Figs.Ia and b has been replaced by a fixed bracket 31, which is attached to the lateral tilt protecting device 9 by a mounting bolt 32. The bracket has an arched control slit 33 in which a control pin 34, attached to the extension leg 5, is slidable bearing against a lower guide surface 35 and an upper guide surface 36. The guide surfaces are shaped such, that the control pin 34 always, independent of the inclination of the lateral tilt protecting device, bears against a part of the guide surfaces 35,36 which is perpendicular to push or pull direction of the control pin. By that is prevented that the end of the extension leg is subjected to oblique load, which is important when the extension leg 5 is in a very protruding position. As an alternative, the extension leg 5 can be pivoted to a coupling link 37 which is fixedly attached to the lateral tilt protecting device 9, as shown in Figs.5a and b. A fork connection 38 is attached to the lower end of the side leg 1, to which connection a control pin 39 is attached. A bracket 40 is attached to the lateral tilt protecting device 9 by mounting bolts 41 and presents an arched control slit 42 through which the control pin 39 extends with the same function as described above with reference to the control slit 33.

The invention is of course not limited to the here shown and described embodiments but can be modified in various ways within the scope of the invention defined by the claims. Hence, the extension leg 5 may, as an alternative, be pulled out from the holding device 4 and after pivoting 180° pushed into the holding device 4 again, in which case there is no need for the holding device to be loosened. It is of course also possible to design the the anti-skid device 18 such, that it can replace the link 7 when necessary for connection with the lateral tilt protection device.

Claims

C L A I M S

1. A ladder with two side legs (1,2) and a number of rungs (3) extending between the side legs, and at the foot end of one of the side legs (2) an extension leg (5) with an anti-skid device (18) to be pressed against a supporting surface, which extension leg is slidably mounted in a holding device (4) fixedly attached to the side leg, which holding device is provided with a locking device (13) that prevents a sliding downwards of the one side leg (2) when the ladder is loaded, and a manually operated release device for permitting adjustment of the extension leg ( 5) , characterized in that the locking device (13) attached to said one side leg (2) is designed to lock the extension leg (5) in both directions , and that the extension leg (5) is provided with a device (6) for detachable interconnection with a lateral tilt protecting device ( 9) , which further is provided with a device (10,11) for detachable interconnection with the foot end of the other side leg (1) .

2.A ladder according to claim 1, characterized in that the locking device (13) includes a pair of V-positioned locking rings (15,16) which are slidably mounted on the extension leg (5) and are positioned between two stop surfaces (21) of the holding device ( 4) , which stop surfaces engage the outside surfaces of the pair of locking rings (15,16) at the closest to each other positioned edge portions, and the pair of locking rings are spaced apart by a compression spring (17) between the pair of locking rings.

3. A ladder according to claim 1 or 2, characterized in that the opposite end of the extension leg (5) in relation to the anti-skid device (18) is provided with a device for interconnection with the lateral tilt protecting device (9), and the extension leg (5) is pivoted 180° for change between use of the anti-skid device and alternatively interconnection with the lateral tilt protecting device ( 9 ) .

4. A ladder according to claim 3, characterized in that the holding device (4) together with the extension leg (5) is pivotal 180°.

5. A ladder according to any of claims 1-4, characterized in that either of the extension leg (5) mounted on one of the side legs (2) or the foot end of the other side leg (1) is equipped with a control pin (34; 39) which is journalled slidable in an arched control slit (33;42) extending in the same direction as the lateral tilt protecting device in a bracket (31;40) attached to the lateral tilt protecting device, and in that the control slit has a guide surface with such a curvature that at all positions of the lateral tilt protecting device in relation to the ladder the control pin (34;39) engages a portion of the guide surface (35,36) that is perpendicular to push or pull direction of the control pin ( 34;39) .

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