The present invention relates to a stair-climbing aid which is to be placed on a tread of an existing flight of stairs and has a height which is approximately half the difference in height between two adjacent treads of said stairs. A stair-climbing aid of this type is disclosed in US Patent 2 782 796. Said aid comprises a walking stick provided at the end with a block of wood having a height which approximately corresponds to half the difference in height between two adjacent treads. The user takes this aid with him or her at every step when negotiating the stairs and uses it for support if necessary. In this way it is possible to reduce the difference in height between two adjacent treads by half.

One of the major problems facing the elderly in living alone is climbing stairs in the home. Climbing stairs in the home constitutes a problem for 15 % of people older than 55. This is caused, inter alia, by the fact that stairs in the home are frequently very steep. The elderly are found to experience difficulty as they get older in bending their knee and hip joints at a large angle, certainly when this is done under a relatively high load (own body weight) and repeatedly. The device according to said US patent has the disadvantage that it is not very stable, necessitates the user moving the stair-climbing aid along with him or her and can give rise to accidents, so that the user takes a fall together with the stair-climbing aid.

It is the aim of the present invention to provide an improved stair- climbing aid which does not have the abovementioned disadvantages and can be used universally on stairs having different differences in height between two adjacent treads.

This aim is achieved with a stair-climbing aid described above in that said aid comprises a base section, provided with fixing means for fixing to the horizontal part of a stair tread, and a step section, which is con¬ nected to the base section and extends horizontally with respect thereto. The invention is based on the insight of fixing the stair-climbing aid firmly to the stairs concerned. That is to say, for a given flight of stairs there are a number of stair-climbing aids equal to the number of treads of the flight of stairs concerned. As a result of the firm fixing, the risk of accidents is avoided. Moreover, it has been found that in order to enable the user to move naturally it is important that the step section located halfway between the treads protrudes somewhat with respect to the

tread on which the base section is fixed. In this way the natural movement of the user is retained, as a result of which the risk of tripping or fall¬ ing is further restricted. Fixing can be effected using any of the tech¬ niques known from the prior art, such as by screwing. As already indicated above, for the purposes of universal applicability it is important that the base section and step section are adjustable with respect to one another in the vertical direction, so that the stair-climb¬ ing aid according to the invention is universally applicable. Angles of stairs in houses have a maximum steepness of 45°, but a broad scale of values down to 16° is encountered.

By allowing the interface between base section and step section to extend obliquely with respect to the horizontal and the vertical, an ad¬ justment in the protrusion in the horizontal direction with respect to the stair tread beneath it is automatically achieved when the height is adjusted. There is found to be a relationship between them.

In addition to the generally known relationship, the so-called "stairs formula", i.e. that the sum of twice the difference in height between the top surface of two treads and the depth of a tread must be between 60 and 70 cm and more particularly is about 63 cm, there must preferably also be compliance with the requirement that when the step section is moved with respect to the base section the resultant displacement in the horizontal direction is about three times the movement in the vertical direction. Natural movement on the part of the user is ensured in this way.

Although it is possible to produce the connection between base section and step section in any of the ways known from the prior art, according to a preferred embodiment one of the sections at the interface between base section and step section is provided with recesses and the other of said sections is provided with protrusions which fit in said recesses. Optimum fixing between base section and step section can thus be achieved by slid- ing said sections sideways into one another, whilst, on the other hand, adjustment in very small increments is possible by means of mutual posi¬ tioning.

So as to be able to continue to make use of the original treads, the length of the aid is preferably less than half of the length of the stair tread concerned. In order to prevent slipping, the step section is provided with anti-slip means on the top.

The invention will be explained below with reference to illustrative embodiments shown in the drawing. In the drawing:

Fig. 1 shows the base section and step section of the stair-climbing aid according to the invention in the disassembled state;

Fig. 2 shows a first application of the stair-climbing aid according to the invention; and Fig. 3 shows a second application of the stair-climbing aid according to the invention.

In the figures, the stair-climbing aid according to the invention is indicated in its entirety by 1. As can be seen in particular from Fig. 1, said aid comprises a base section 2 and a step section 3. Both the base section 2 and the step section are provided with sloping faces. The base section 2 is provided with protrusions 9, between which openings 10 are defined. The step section 3 is provided with protrusions 11, provided with openings 12. Said protrusions 11 having openings 12 can be pushed from the side into, respectively, openings 10 and protrusions 9. In this way it is possible to place the step section 3 in various positions with respect to the base section 2, the top surface of the step section 3 always remaining parallel to the bottom surface of the base section 2, that is to say is always horizontal in the normal position. The step section is provided with an anti-slip profile 13 on the top. 15 indicates a rubber band or belt, such as an O-ring, stretched around both the base section 2 and the step section 3. When step section 3 and base section 2 are pushed into one another, underlying movement will not be hindered by the presence of the rubber component 15, because this has a fairly small volume as a result of the tension under which it is fitted. After the sections have been slid into one another, the rubber belt 15 is cut through, as a result of which said belt becomes free and moves in the gap between the adjoining sections at increasing the volume per unit length thereof. As a result, movement of sections 2 and 3 relative to one another is made more difficult. In this way, the relatively large tolerances which are inherent in specific produc- tion methods, such as extrusion, can be taken up without giving rise to difficulties in assembly. In this way a play-free fixing can be achieved. Any free ends can, moreover, serve at the same time to grip a finishing strip which is to be fitted on the front ends of both the base section and step section 3 and is not shown in more detail. These finishing strips can serve as definitive fixing for the sections 2 and 3.

It must be understood that the principle of assembly with the aid of a rubbery component which is under tension, and thus has a small volume, in the case of sections having a relatively large mutual tolerance and the

subsequent increasing of the volume of the rubbery component by, for example, cutting through, so that the play between said sections disap¬ pears, is generally applicable. A possible example in the building trade is the assembly of all sorts of products, such as door or window frames, in which case it is no longer necessary to use mastic or the like.

Fig. 2 shows the application of the stair-climbing aid according to the invention with a relatively shallow flight of stairs. Said stairs are com¬ posed of treads 6 having horizontal parts 7, to each of which the base section 2 is fixed in any manner known from the prior art. With this arrangement, the front end of the base section 2 preferably extends to be approximately flush with the front edge of the tread 7 con¬ cerned. With this arrangement the slope of the interface between step sec¬ tion 3 and base section 2 is so chosen that if the height (a) between the original tread and the top of the step section changes, the step section alters its position in the horizontal direction by a factor of 3 times said change. The steeper the construction of a flight of stairs, the smaller becomes the distance (d) . The fact that distance (d) becomes smaller is partially compensated for in the horizontal direction by the position of the step section, because the protruding part (c) becomes larger. This condition is in addition to the generally known stairs formula, according to which the sum of twice the difference in height between the tops of two treads and the depth of a tread is between 60 and 70 cm and preferably is 63 cm.

Although the invention has been described above with reference to a preferred embodiment, it must be understood that numerous modifications can be made thereto without going beyond the scope of the present Application.

For instance, fixing of the base section with respect to the step sec¬ tion can be effected in other ways known from the prior art. It is not absolutely essential that the interface between the step section and the base section is oblique. The same effect can be achieved using a step- shaped interface between the two sections. It is also possible for the base section and step section to be firmly joined to one another in the factory, so that various ranges are provided for various types of stairs. An embodi¬ ment in which the base section and the step section are of identical con- struction is likewise to be preferred for production engineering reasons. Finally, it is possible to fit a side finishing plate so that the way in which the step section and base section engage in one another is not vi¬ sible and is fixed by the side finishing plate and the chosen position. All

such modifications are considered to fall within the scope of the present Application, as described in the appended claims.