GB2140386A - Lifting mechanism for showing eg a play surface - Google Patents

Abstract

A lifting mechanism comprises at least three, preferably four, wires or similar filaments 9, 10, 11, 12 each secured at one end e.g. 27 to a point associated with the play surface and at the other to a fixed point e.g. 22 remote therefrom and each is entrained over a pulley e.g. 25 mounted about a fixed axis and over a pulley e.g. 26 mounted about a laterally movable axis 32. Axis 32 is moved by a screw-and- nut device powered by two revisible electric motors 37, 38 via belt drives 39, 40. The current powering these motors may be switched to power, e.g. a model railway layout. <IMAGE>

Description

SPECIFICATION Stowable play surface The present invention is concerned with a play surface which can be stowed away when not in use. It is of value, among other purposes, for model railway layouts and table games such as snooker, billiards and pool but it is also applicable to functional surfaces such as for working upon or in domestic applications.

The biggest difficulty with a play surface for a model railway or for a table game is that it usually requires a larger area than is conveniently available in an average home. Thus a railway layout measuring, say, 3.5 metres by 1.5 metres is too large for permanent display in the average domestic room but, unless it is to be dismantled after each use, there is the problem of where and how to stow the layout until it is next required. Table games of the type of snooker and pool have become increasingly popular over recent years but again there is little room for such a table game in the average home.

It is an important feature of my invention that it allows a play surface of the abovementioned types to be raised horizontally to the ceiling for stowing when not in use, thus freeing the previously-occupied space for other purposes. An incidental advantage is that the play surface is thereby stowed in a relatively dust-free area.

The stowable play surface according to my invention incorporates a lifting mechanism which comprises at least three wires or similar filaments, eaoh of said wires being secured at one end to a point associated with the play surface and being secured at its other end to a fixed point remote from the play surface, each of said wires being entrained over a pulley mounted about a fixed axis and over a pulley mounted about a laterally movable axis, and means to vary the distance between the fixed axis and the movable axis.

I should emphasise that, in using the words "play surface", I do not wish to imply that the surface of the device which I have invented must necessarily be used for play or leisure, although such activities do indeed represent an important possible use thereof. It will readily be understood that the surface may alternatively perform a work or business function. Thus my invention is equally usable as a work surface, for example for manual work or for drawing upon, or as a domestic surface, for example as an occasional table.

The play surface may be any desired shape, for example round, square or irregular, but for many purposes it is most convenient for the surface to be rectangular or oval. The surface need not be continuous acr ss its width; for example it may take the form of a flat annulus or may have one or more cut-outs to afford ready access to areas of the surface away from its perimeter.

The play surface is suspended, at least during transit between its stowed position and its position of use, by at least three wires or similar filaments. For most purposes, I prefer to use four such wires or the like. In view of the likely weight of the play surface, which often will have attachments such as model railway track and model buildings and may also carry the drive mechanism by means of which it is raised and lowered, I prefer to use wire, especially steel strand. However it is also possible to use rope or cord, either of which may be of natural or synthetic material.

Each of the wires or similar filaments (which for convenience I shall refer to hereafter simply as "wires" is secured at one end to a point associated with the play surface. Thus the wire may be secured to the surface itself or may pass through it and be secured for example to its underside. At its other end, the wire is secured to a fixed point remote from the play surface. Thus, for example, the wire may be secured to the ceiling above the position of use of the surface. As another possibility, the wire may pass over a pulley on the ceiling and then be secured elsewhere, for example on an adjacent wall.

Each wire passes over at least two pulleys, the first of which is mounted for rotation about a fixed axis and the second of which is mounted for rotation about an axis which can be moved laterally, that is in a direction other than an axial direction. By effecting relative movement of these two pulleys so as to increase or decrease their distance apart, it is possible to change the path length of the wire between its ends and thereby to raise or lower the suspended play surface.

In a particularly preferred form of my invention, the wire leading to the movable pulley and the same wire running away from that pulley follow essentially parallel paths, so that a loop of wire is formed with the movable pulley at its apex. In this way, a given linear movement of the movable pulley may produce a shortening or lengthening of the path of the wire equal to twice that amount. It will be recognised that by further looping of the wire about the movable pulley the effect may be further enhanced.

Relative movement of the fixed and movable pulley, that is movement of the movable pulley towards and away from the fixed pulley, may be achieved in a variety of ways.

Thus the movable pulley may be mounted on a lever, which may be manually operable or may be suitably driven. A greater degree of fine control may be achieved by means of my preferred arrangement, which entails moving the movable pulley by rotating a threaded screw. Thus the movable pulley may be mounted upon an internally threaded driven member which engages an elongated threaded drive member and rotating the drive member. The threaded drive member may be rotated manually, as by a hand-wheel or lever mounted thereon, but I particularly prefer to provide electrical drive means for the drive member.In the case, for example a model railway layout, where electric power is required at the play surface for operating com ponents or tools thereon, the power may be switchable between a first operating mode where it drives the mechanism for raising and lowering the play surface and a second operating mode where it is supplied for use at the surface.

The invention will now be further described, and other features thereof will be made more readily apparent, by reference to the accom panying drawings, which illustrate one preferred embodiment of my invention. In the drawings: Fig. 1 is a plan view of the operating mechanism, with the play surface itself omitted for the sake of clarity; and Fig. 2 is a sectional view, taken on the line Il-Il of Fig. 1.

The illustrated device comprises a main frame formed from square cross-section tube and consisting principally of parallel side members 3 and 4 and an end member 5.

Running transverse to the length of the main frame are cross battens 7 and 8, which extend sideways from the main frame to form side-arms 7a, 7b, 8a and 8b. These side-arms are the members by which the play surface is suspended from the ceiling and, together with the main frame itself, they provide the base for the play surface.

Associated with each of the side-arms 7a, 7b, 8a and 8b is a suspension wire, designated by the numerals 9 to 1 2 in the drawings. Each of the suspension wires passes over a pulley (13 to 16), mounted on a suspension carriage (17 to 20), adjustably secured to the respective side-arm so that the distance of the carriage away from the adjacent main frame member may be varied as desired. The suspension wires at their upper ends are secured to the ceiling 21 as at 22, 23.

The paths followed by the suspension wires through the main-fframe may be easily seen by reference to Fig. 1 of the drawings. Referring to the left-hand side of that Figure, the suspension wire 11, leaving the pulley 1 5 of the carriage 1 9 on the side-arm 8a, runs inwards towards the main rame and is diverted by a pulley 24, also mountedonside- arm 8a, to run parallel to the side member 3.

The suspension wire 11 joins the suspension wire 9 adjacent the side-arm 7a and the two wires pass in parallel over a twin pulley 25.

The wires 9 and 11 now follow parallel paths, forming a loop over a further twin pulley 26 before being anchored together at 27 on end member 5.

The suspension wires 1 2 and 10 follow similar paths on the right-hand side of the main frame, passing over a pulley 28 (wire 1 2 only) and twin pulleys 29 and 30 before being anchored together at 31 on the end member 5.

The two pulleys 26 and 30 are mounted so as to rotate freely on a cross-bar 32, which at its ends slidably engages the side members 3 and 4 to enable it to move in a direction parallel to the length of the main frame.

Cross-bar 32 is secured to an internally threaded brass nut 33, which engages the threads of an elongated drive screw 34, jour nalled at one end at 35 in a fixed cross member 36.

Thus rotation of the drive screw 34 moves the slidable cross-bar 32 towards or away from the fixed cross-member 36 and reduces or increases respectively the size of the loops in the wires around the pulleys 26 and 30. In this way the whole assembly is lowered (with the assistance of gravity) or raised repectively away from or towards the ceiling 21.

Rotation of the drive screw 34 may be achieved as desired by means of an electric motor or a selected combination of electric motors. In the illustrated embodiment, two reversible motors 37 and 38 are shown, working together via drive belts 39 and 40 engaging a twin pulley 41 on the end of the drive screw 34. Alternatively, different motors may be used for raising and lowering the assembly, for example one motor for lowering it and two working together to raise the assembly.

The overall dimensions of the play surface incorporated in the illustrated embodiment of the invention are a matter of choice. A small version thereof may measure perhaps 2.5 metres by 1.2 metres and a much larger version may measure of the order of 5 metres square.

While, in the illustrated embodiment, the lifting mechanism is mounted on the main frame which itself carries the play surface, it is equally possible for the lifting mechanism, incorporating all of the illustrated components, to be mounted upon the ceiling, or even upon an adjacent wall. Those ends of the suspension wires which in the illustrated embodiment are secured to the ceiling are instead secured to the lifting surface but in all other respects the mechanism operates in exactly the same way.

The control of operation of my novel device may be designed to meet the particular needs of the user. However, I prefer to operate the device using a switch either mounted upon an adjacent wall or suspended from the ceiling.

By means of such a switch, power may be switched on and off to the drive motor or motors and/or the direction of operation may be reversed and/or the power may be transferred from the drive to the play surface itself, in order for example to power a model railway layout. If desired, one or more limit switches may be incorporated in the design, to cut out the drive and/or to reverse it at the ends of the path of travel of the play surface. Addi ticnal in situ control may be afforded by means of a further switch (e.g. a push button) mounted upon the play surface itself.

Claims (10)

1. A stowable play surface incorporating a lifting mechanism which comprises at least three wires or similar filaments, each of said wires or similar filaments being secured at one end.to a point associated with the play surface and being secured at its other end to a fixed point remote from the play surface, each of said wires or similar filaments being entrained over a pulley mounted about a fixed axis and over a pulley mounted about a laterally movable axis, and means to vary the distance between the fixed axis and the movable axis.

2. A stowable play surface as claimed in claim 1, comprising four such wires or similar filaments.

3. A stowable play surface as claimed in either of the preceding claims, wherein each wire or similar filament is led towards and away from the movable pulley along essentially parallel paths, so as to form a loop about said pulley.

4. A stowable play surface as claimed in any of the preceding claims, wherein the means to vary the distance between said fixed axis and said movable axis comprises a lever upon which said movable pulley is mounted.

5. A stowable play surface as claimed in any of claims 1 to 3, wherein the means to vary the distance between said fixed axis and said movable axis comprises a rotatble threaded screw.

6. A stowable play surface as claimed in claim 5, wherein the movable pulley is mounted upon an internally threaded rotatable drive member.

7. A stowable play surface as claimed in claim 6, wherein said elongated drive member is rotated by electrical drive means.

8. A stowable play surface as claimed in claim 7, wherein switch means are provided to enable the electric power to be switched between a first operating mode where it drives said drive member and a second operating mode where it is supplied for use at said surface.

9. A stowable play surface as claimed in any of the preceding claims, incorporating one or more limit switches to cut out the drive and/or to reverse it at the ends of the path of travel of said play surface.

10. A stowable play surface substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.