The present invention relates to work platforms, used for example in the building industry, or for installation and repair work, e.g. in water or electrical services or in erection work with large machines.

Work platforms of this type have been made with a supporting structure incorporating a system of arms, either ^* in the form of a parallelogram linkage sytem or as scissors. In other embodiments, the work platform is movable along a vertical mast or guide means, attached to a basic frame.

The vertical movement of the work platform is provided by machinery, most often electrically driven.

Vertically movable platforms of these known types are often large and heavy, and thereby difficult to handle for- minor jobs. They are also so expensive that they can hardly be used for such worko

The present invention has the object of providing a very simple and cheap work platform, primarily intended for erection, installation and repair work and for being put to use in small building jobs. This object is achieved in a very simple manner by forming the work platform to coact with a anoeuverable lifting machine and to have a platform which is movable vertically. At its first end the platform has a vertical support with guide means adapted for guiding vertical movement at this end, and has at its second end support an'd carrier means for coaction with machine-driven, vertically movable lifting means on the lifting machine, e.g. the tynes of a fork-lift trucko

A lifting means for the platform comprises two carrier means, which are variable as to their lengths, the first carrier means carrying the first end of the platform and being arranged between the latter and the top of the guide means, while the second carrier means is arranged between the second end of the platform and an attachment arranged under the lowest position of the platform, this attachment being mounted on the lifting machine carrying the movable lifti,

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means. The carrier means are so connected to each other that for platform movement the second means is shortened just as much as the first means is extended, the platform being parallel-displaced upwards. For the opposite variation in length of the carrier means, the platform is moved downwards The invention will now be described in more detail whil referring to the appended drawing, showing a work platform i coaction with a fork-lift truck.

The entire work platform with supports is designated by the numeral 10 in the figure, while 11 designates a fork-lif truck. The work platform comprises a platform 20, a vertical support means 30 along which the platform 20 is vertically movable, and a lifting or operating means 40 for raising and lowering the platform 20. The platform 20 comprises a longitudinal beam structure 21, a walkway 22 and surrounding ..railing 23, comprising post and horizontal handrails. At its first end, to the left in the drawing, the platform 20 is carried by a vertical suppor means 30, described in more detail below. At its second end, to the right in the drawing, the platform i-s carried by the tynes 12 on the fork-lift truck 11. The tynes 12 can be inserted in tubes or channels 27 and be locked thereto, e.g. with the aid of through-holes and bolts or clamping means. A beam 27 is arranged for each tyne on the fork-lift truck 11 and the beams are connected together into a framed structure. Said structure has brackets 26 carrying a shaft 25, which also coacts with brackets 24 on the frame 21 of th platform 20 at its second or right end. The platform 20 and the truck 11 are thus articulated in relation to each other about the shaft 25 ₀ When the work platform is not in use, it rests on the ground via the support means 30 and the beams 27

The support means 30, carrying the first or left end of the platform 20, comprises one or more vertical tubes or beams 31, which can slide in guides 28 on the platform.20. The beam or beams 31 are preferably unrotatably connected to the platform 20, but are disposed for movement substantially at right angles to the platform. The support 31 has at its upper end a carrier structure 32 for a rotatable

pulley 45, which is part of the operating means 40. At its lower end the support 31 is provided with a castor wheel or wheels 33, pivotable about vertical shaft stubs 34. By means of this arrangement, the work platform can be driven and manoeuvered by the truck in desired directions.

Operation of- the platform 20 vertically is done by means of an apparatus primarily comprising traction means such as one or more cables and cable pulleys. In the figure, a cable is denoted by the numeral 41, one end portion 41' of which is fixed to an attachment 42 on the downward, front end part of the fork-lift truck. The cable portion 41" is taken upwards and round a rotatable cable pulley 43, which is arranged on the shaft 25 or in the vicinity thereof. From the cable pulley 43, the cable 41 extends along the platform 20 to the first or left end thereof, and to a rotatable cable pulley 44, which is mounted on the under side of the platform 20. From the cable pulley 44, the cable.41 is taken with a substantially, vertical portion 41" over a rotatable cable pulley 45 mounted on the upper end of the support 31 and thereafter downwards outside the platform 20 and outside the support 31 to an attachment point 46 on said support. In the embodiment illustrated, the attachment point 46 is arranged at one end of a turnbuckle 47, the other end of which having anattachment point 48 rigidly connected to the lowest portion - ₀ f the support 31.

The platform 20 is moved upwards and downwards by raising or lowering the- tynes 12 of the fork-lift truck 11. When the tynes are raised, the second end of the platform 20 is raised via the framed structure with the parts 25-27, carried by the tynes 12 of the fork-lift truck 11. The coacting structure 24 on the platform 20 is also lifted by the intermediary of the shaft 25. When the platform 20 is raised, the portion 41* of the cable 40 will _r be extended by the cable 41 under the platform being pulled out to the right or second end of said platform. This movement signifies that a corresponding length of the cable is taken away from the cable portion 41", which thus becomes shorter. It will be noted that the extension of the cable portion 41*

to the shortening of the cable portion 41". This signifies that the first or left end of the platform 20 maintains an unaltered height in relation to the second end of the platform, and that the platform is thus displaced parallel upwards. When the "tynes 12 of the fork-lift truck are lowered, the cable portion 41 * is shortened and the portion 41" is extended, and the platform 20 is displaced parallel downwards in an analogous manner. With the aid of the described arrangement, the lifting machinery of the fork-li truck is thus utilized for raising and lowering the work platform, which thus does not need its own driving machiner As described above, the cable 41" runs over a rotatabl cable pulley 45 and down to a turnbuckle 47. This arrangeme constitutes a device by means of which the horizontal attitude of the platform 20 can be adjusted. For example, i the firs-t or left end of the platform is lower than the second end, the turnbuckle 47 is rotated so that the attach ment point 46 is moved downwards. The cable portion 41" wil thus be pulled upwards round the pulley 45 and be shortened thereby lifting the first or left end of the platform so th the latter can be adjusted with the same height at both end If, instead, the first or left end of the platform 20 is higher than the second end, the turnbuckle 47 is rotated so that the cable pulley 44 and thereby the first or left end the platform 20 is lowered to the desired position. An adjustment of the horizontal attitude of the platform in th way described results, for example, in that the platform 20 can be brought to a horizontal attitude and subsequently be moved upwards and downwards without this attitude being altered even if the substructure is such that the castor wheel or wheels 33 are somewhat lower or higher than their normal position in relation to the wheels on the fork-lift truck 11.

One embodiment of the invention has been described above, but anyone ^' skilled in the art can naturally easily provide other embodiments within the scope of the appended patent claims. For example, a hydrostatic system can be use instead of the described lifting or operating arrangem

and the adjustment means 46-48 can be built up from elements other than a turnbuckle, to mention just a few examples.