Patent Grant
9976347
The present invention relates to a ladder and especially to a safety device for it enabling a safe positioning against an object like a pit wall when for example being propped up in an elevator shaft.
It is a matter of regrettable fact that the number of accidents associated with the use of ladders is still too high resulting in serious and in some instances fatal injuries. In most if not all instances, the reason for such accidents is inadequate anchoring of the ladder when being in position angled against a wall or similar structure. Many and varied arrangements have been proposed for stabilizing the ladder in its use position. For example, legs attached to the stiles of the ladder have been suggested for additional contact with the ground to give more stability and struts for contact with the supporting wall have also been proposed.
To this end, the safety demands for entering into a pit of an elevator shaft have been intensified as this is to be read in the EN 81-20 regulations. So, the maximum weight of the ladder shall not exceed 15 kg in order to allow its easy and safe handling from the landing sill (some national regulations may even request a maximum weight less than 15 kg for manual handling) and the safe use of the ladder in its position of use shall be ensured by means of a device securing the ladder to the landing sill, or the bottom of the pit, or the wall of the well. At least, the risk of a person tipping over of the ladder when standing or grasping the upper part of the ladder above a landing sill level shall be prevented by means of appropriate measures.
From a technical point of view, it is critical to minimize the impact of these requirements for a layout design of standard elevators. A more specific type of ladder support for ladders intended for a use in pits finds form in a bracket attachable at the ladder with a clamp for positive engagement with for example a wall or landing level of an elevator shaft. In use the ladder is anchored at its top end to the floor edge, thus assisting in the prevention of inadvertent slippage away from the intended orientation of the ladder against the wall of the shaft. One such bracket for a modular ladder with an adjustable sill hook profile is described in EP 1 609 943. A locking device is provided at the sill hook profile being parallel adjustable to a longitudinal axis of the ladder rail being therewith fastened over a support or directly over a pit level.
An additional request would be the ease of installation and use during the installation and maintenance. The future usage of this invention would be all elevators requiring a pit ladder.
It is therefore a general object of the present invention to provide an improved ladder and a convenient support device which facilitates an attachment of the ladder to a structure against which the ladder is to be placed in a leaning orientation to prevent tipping of the ladder, especially when a person grasps a part of the ladder above a landing sill level, and to find a solution for a convenient placement of such device when the ladder is not in use. The latter shall aim to arrange the ladder parallel to a pit wall so that the ladder can remain in the shaft even when a car is moving in the shaft.
Basic idea of the invention is thus a provision of a ladder with integrated tipping protection and integrated landing fixing by simultaneously creating a space saving structure when the ladder is not in use. To this end, there is provided a ladder support bracket having a support shoulder for creating a support contact with a complementary structure like the plane of a floor, wherein the bracket further comprising at least one jaw for joining the bracket to an elongated rail of a ladder, the jaw having a retainer mechanism by means of which the bracket can be brought into a clamping position attaching the bracket unmovably to the rail and a resting position holding the bracket in swivel connection relative to the rail and/or movably along at least a section of such rail.
The complementary structure in the simplest case is a horizontal floor surface at the upper edge of a pit. To realize a good support contact the support shoulder advantageously comprises a bearing surface for being put onto said horizontal floor level.
To bring said support shoulder in stable contact with a ladder, the ladder support bracket comprises at least one jaw for joining the bracket to an elongated rail of a ladder, i.e. the one which is upstanding when propping up the ladder. A ladder meant herewith in the application includes two of said upstanding rails which are interconnected by a plurality of rungs.
As the ladder weight is limited according to the regulations—see for example EN 81-20—the inventive concept heeds to not add extra weights to the ladder. The ladder meant by the invention can have a weight of about 5 kg, only. The ladder can show a foldable construction, which minimizes the layout impact of the ladder. The structure of the support bracket permits the fixing to be placed in the correct location between ladder rungs. The design is made to be flexible by being fixable to the correct position for putting the ladder in use by the installation or maintenance crew. The design also prevents the tipping of the ladder by moving the critical point in the structure further away from centre of gravity. When the ladder is to be put into a storage position at the wall site, the fixing structure, namely the support bracket is to be folded down into the ladder plane and thus minimizes the impact of the ladder to layout drawings.
The inventive ladder
The upstanding rails may include a rotary joint in order to make the ladder foldable; however this is not a must. Even a plurality of those rotary joints may be present in order to make the ladder foldable in a multiple manner.
Essential for the invention is that said jaw has a retainer mechanism by means of which the support bracket can be brought into at least two positions when having arranged the inventive support bracket at a ladder. The first position concerns a clamping position attaching the bracket unmovably to such a rail. The second position is a resting position holding the bracket in a swivel connection relative to the rail. Optionally, there is also a possible traverse-movement of the bracket along at least a section of the rail. As regards the clamping position in which the bracket is fixed to the ladder a relative position between the ladder and its support bracket is realizable to create a safe placement of the ladder against an object like a pit wall by having placed the inventive bracket conveniently against the pit wall or pit wall edge, meaning for example onto the floor-ground at the upper end of the pit. By propping up the ladder in this way the created support contact of the support shoulder with said complementary structure, i.e. the floor edge eliminates a tipping of the ladder. This means that due to that at least a part of the support shoulder is placed on the horizontal floor level, the ladder can no longer be turned around in that plane corresponding to the wall against which the ladder is propped up. This is especially an advantage when a person is standing or grasping the upper part of the ladder above said floor level since this has been in prior art the most often case of having pushed the ladder to one side when grasping one of the rail-ends.
As regards the resting position of the support brackets, the same is in a swivel connection relative to a ladder's rail. By means of this measure the support bracket can be brought into a resting position for the case the ladder is not in use. The movement for bringing the support bracket from an acting position in which the support shoulder enhances the support of the ladder, into the resting position and vice versa is realized best by means of a swivel turning movement. Pivoting the support bracket between these two positions conveniently takes place about an axis which is parallel to the rungs of the ladder or other said about one being perpendicular to the longitudinal axis of a rail.
By means of the optional shifting movement of the support bracket along at least a distance or section of a rail the relative position between the support bracket and the ladder as such can be adjusted to bring the support bracket into a convenient height in dependency of the pit wall-altitude. Additionally, such a traverse-movement can help to further swivel the bracket down into the ladder's plane formed by the rails. The more the bracket is shifted away from that adjacent rung towards which the bracket is to be swivelled against, the further it can be pivoted into the ladder's plane.
To realize a good contact between the support shoulder and the horizontal floor level, the support shoulder advantageously comprises a bearing surface for being put onto said horizontal level. Further, according to a convenient improvement the bearing surface is at least partially completed with a supporting edge surface which is formed rectangular to the bearing surface. Therewith, the support shoulder is made complementary to the floor edge enhancing stability of the position between ladder and pit wall and floor edge. So, according to the last elucidated embodiment the support shoulder comprises two surfaces which can be exactly laid on a floor edge against which the ladder in question is to be propped in the acting position of the bracket. In this respect, it is convenient to make the bearing surface of the support shoulder which shall be put onto the horizontal floor level bigger than the supporting edge surface which is to be placed against the vertical pit wall. This leads to that according to a convenient embodiment, the resting position of the bracket shall result from a swivel movement of the bracket by positioning the support shoulder with the bigger one of its support surfaces (being in this case said bearing surface) into a plane which corresponds by the two rails of the ladder. Therewith, a space saving structure is realized according to which the support bracket does especially not protrude from the outer circumference of the ladder in the resting position of the bracket.
It is to be noted that it is also possible that the supporting edge surface engages into a groove which is made vertical into the floor section. This enhances a further time the halt of the ladder since then it is even eliminated that the ladder tips back into the pit.
According to a further development of the invention, the retainer mechanism of the support bracket is formed such to encircle or encompass a rail by having further a tensioning bolt acting as an actuator for the clamping position and the resting position, respectively. The used terms “encircle or encompass” do not mean obligatory to that the jaw completely touches the rail in question. Quite to the contrary, it is sufficient to that only a part of the outer surface of a rail is clamped by the jaw. In case a ladder rail is formed by a cuboid block it is sufficient to that the jaw clamps the rail by touching two of parallel block-walls and leaving a free space between the other two parallel block-walls.
The above thoughts lead to a development of the jaw in that sense that the jaw is built in the form of trapeze with pairs of parallel walls encompassing the ladder rail in an abutting manner when being in the resting position. A possible design for this structure can be for example seen in the embodiment outlined in the following drawings.
According to any of the elucidated embodiments it is convenient to provide the ladder bracket with two jaws which are to be mounted to both rails of a ladder, respectively.
Therein,
In
Such a swivelled position is shown in
Due to the clamping position the load on the ladder is partly supported by the support shoulder. Thereby it tilts the rails relative to the retaining mechanisms such that the jaws grip the rails, leading to a securing the ladder from tipping. For the resting position in turn, namely when the ladder is lifted up from the landing sill, the support bracket drops freely and can be tucked to the resting position for minimal footprint when stored on the shaft wall.
All features shown or discussed with respect to particular embodiments of the invention can be combined in various applicable combinations in order to realize their positive technical effects simultaneously.
The scope of the present invention is given by the claims only and is not restricted by the exemplary embodiments discussed in the description or depicted in the figures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15180734 | Aug 2015 | EP | regional |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3853202 | Jarboe | Dec 1974 | A |
| Number | Date | Country |
|---|---|---|
| 1 609 943 | Dec 2005 | EP |
| 2013-213407 | Oct 2013 | JP |
| 2013213407 | Oct 2013 | JP |
| 2014-34795 | Feb 2014 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20170044830 A1 | Feb 2017 | US |
