This invention relates to a hoisting device of the type which comprises an elongate support member having parallel tracks for a load-carrying carriage and a winch the cable of which is connected to the carriage to pull the loaded car¬ riage along the support member.

US-A-4 183 423 discloses a hoisting device of this kind which is designed to be easily transportable from one place to another and to lend itself to use where there is a tempor- ary need for moving loads between different levels, such as from the ground to an upper floor or the roof of a building. One example of typical situations in which the lack of inexpensive and readily erectable and movable load-handling devices often means that there is no economically realistic alternative to manual moving of loads, such as building mate¬ rials, small machines etc., between different levels, is con¬ struction or repair or maintenance work which is carried out on the an upper floor or the roof of a small house or other low building. The general object of the present invention is to pro¬ vide an improved hoisting device of the kind described above. A more particular object of the invention is to provide a hoisting device of the kind described above which is simple and inexpensive, can be quickly erected on the site of use and can be quickly disassembled for transport and storage.

To this end there is provided according to the invention a hoisting device comprising an elongate support member having a track, a carriage which is detachably supported on the track for movement along the support member and includes a winch cable attachment member and means for carrying a load, a top member having means for attaching it to the other end of the support member, a base member including means for detachably connecting it to one end of the support member, a winch comprising a winch cable and mounted on the base member, and

a cable guiding member mounted on the top member for guiding the winch cable between the winch and the carriage.

The invention will be described in greater detail below with reference to an exemplary embodiment shown in the accom- panying drawings, in which:

Fig. 1 is a side view of a hoisting device embodying the invention;

Fig. 2 is a front view of the hoisting device of Fig. 1;

Fig. 3 is a cross-sectional view on line III-III of Fig. 2;

Fig. 4 is a fragmentary view showing two interconnected sections of the supporting member of the hoisting device;

Fig. 5 is a cross-sectional view on line V-V of Fig. 4.

As illustrated in the drawings, the exemplary embodiment of the hoisting device according to the invention comprises the following main parts which can be easily and quickly assembled and disassembled:

- An elongate, ladder-like support member 11 having a pair of parallel side rails 12 which form a track; - A carriage or trolley 13 which is movable along the track on the support member, being supported thereon by flanged front and rear rollers 14 engaging the side rails 12;

- A base member 15 having mounted thereon a winch 16 which is driven by an electric motor and comprises a winch cable 17, one end of which is attached to the carriage 13, and also having mounted thereon a holder 18 receptive of one end, the lower end, of the support member 11;

- A top member or head 19 which is detachably mounted on the other, upper end of the support member 11 and provided with a pulley 20 guiding the winch line 17.

As already mentioned, the support member 11 resembles a ladder and in the illustrated exemplary embodiment is actual¬ ly a conventional commercially available ladder of the very commonly occurring type which is made of aluminium or other light metal and comprises two I-section side members inter¬ connected by a plurality of tubular rungs of square rounded cross-section the ends of which are passed through and rigid¬ ly connected with the side member webs by an upsetting oper-

ation. Ladders of this type are characterised by a very high load-bearing capacity and low weight and are commercially available in several different lengths and transverse dimen¬ sions. As shown in Fig. 3, the upper flange 12A of each side rail 12 of the support member 11 forms a track for the rollers 14 on one side of the carriage 13. The side rails 12 are symmetrical in cross-section so that both flanges can serve as the track. In the illustrated embodiment, the carriage 13 comprises a square, substantially planar frame with two side members 21 which are interconnected by front and rear crossbraces 22. These crossbraces also serve as axles in that their ends pro¬ trude beyond the outer sides of the side members and support the front and rear rollers 14 for rotation. The inner sides of the rollers are provided with flanges 14A which guide the carriage against the inner edge of each upper flange 12A of the side rails 12.

A pair of laterally spaced upper arms 23 are pivotally mounted on the front crossbrace 22 and a pair of laterally spaced lower arms 24 are pivotally mounted on the rear cross¬ brace 22. These arms 23 and 24 can be raised from a folded- down position (Fig. 2) alongside the side members 21 and interconnected in a selected position such that the first pair of arms 23 forms a load platform supported by the second pair of arms 24 as shown in Fig. 1.

A metal ring 25 is secured, such as by welding, to the front crossbrace 22 and serves as an attachment member for the end of the winch line 17. Outside each roller 14 on the front crossbrace 22, a smaller roller 26 is rotatably mounted on a bracket 27 which is adjustably secured to the end portion of the crossbrace. The bracket is securely held to the crossbrace by means of a set screw 27A or some other suitable locking means. In use of the hoisting device, the brackets 27 are positioned such that the rollers 26 lie between the outer portions of the upper flanges 12A of the side rails 12 close to the lower or inner side of these flange portions. In this

position the rollers 26 serve as retaining means to prevent the front rollers 14 of the carriage 13 from becoming disen¬ gaged from the side rails 12, e.g. under the influence of a load on the carriage tending to overturn the carriage about the rear rollers 14.

The base member 15 comprises a rectangular base plate 28 which in use of the hoisting device engages the ground or some other suitable supporting surface. The base plate 16 supports the winch 16. Mounted on the base plate 28 is also the holder 18 for the lower end of the support member 11. The holder 18 com¬ prises a pair of short tubular sockets 29 and a crossbrace 29A which is rigidly connected with the tubular sockets 29. Adjacent one end thereof, the tubular sockets 29 are pivot- ally mounted on aligned pivot pins 30 carried by the base plate 28 on opposite sides of the winch 16 so that the holder 18 can be pivotally moved about an axis A which is parallel to and close to the base plate, the crossbrace 29A being positioned such that it clears the winch. The tubular members 29 are open at their ends remote from the pivot pins 30 and they are spaced apart and dimen¬ sioned such that they can receive the protruding lower end portions of the side rails 12 of the support member in plug- and-socket fashion. When received in the tubular members 29, the end portions of the side rails 12 rest on the pivot pins.

The head 19 comprises a pair of short tubular sockets 31 and a crossbrace 32 which is rigidly secured to the tubular sockets 31, such as by welding, and on which the pulley 20 is mounted. One end of the tubular sockets 31, the lower end, is open while the other or upper end is closed. Moreover, the sockets are dimensioned and spaced apart such that they can be slid over the protruding upper end portions of the side rails 12 of the support member 11 in plug-and-socket fashion. When the hoisting device is to be erected for use in transporting a load between two different levels, such as for hoisting building materials from the ground to an upper floor or the roof of a building, the base member 15 is placed in a suitable position on the ground. Then the lower end of the

support member 11 - on the upper end of which the head 19 has previously been mounted as described above - is slid into the sockets 29 of the holder 18 and the upper portion of the support member is allowed to take support against the wall or roof of the building in a suitably inclined position.

The carriage 13 is then positioned on the track formed by the side rails 12. In order that the rollers 26 on the brackets 27 may not interfere with this positioning, the brackets are first displaced outwardly so that the rollers 26 clear the flanges on the side rails. When the rollers 14 of the carriage properly engage the side rails, the brackets are then moved to the position shown in Fig. 3 and secured in this position. The winch line 17 is passed over the pulley 20 and attached to the ring 25. After the winch 16 has been connected to a suitable current source and the load has been placed on the carriage 13, the winch 16 is operated by means of a control box B to pull the carriage up the support member 11 to the upper floor or the roof where the load is removed. Naturally, loads can also be transported from the upper level to the ground. If desired, the person or persons operating the hoist may use the support member 11 as a ladder to climb up and down.

When the hoisting device is to be transported to a dif¬ ferent place, it is disassembled into its main parts. The carriage 13, the base member 15 and the head 19 can be placed in a suitable box or secured together in a suitable manner to form a compact and easy-to-handle unit. The support member 11 is handled separately.

If required, the support member can be extended by join- ing two support member sections together as shown in Figs. 4 and 5. A pair of joining members 33 of channel section are placed against the outer sides of the webs of the side rails 12 of the support member sections to be joined. The joining members are then clamped by means of tie rods 34 passed through the tubular rungs 35. It should be noted that if joining members 33 are used as described, the rollers 26 have to be positioned under the side rails 12 instead of between the flanges as shown in Fig. 3.

To prevent personal injury or damage to the hoisting device or the load in case the cable 17 or the brake of the winch 16 fails, the carriage 13 can be provided with at least one safety hook or catch (not shown) coupled to the winch cable 17. When subjected to the pull of the winch cable 17, the safety hook or catch is held in an inactive position in which it clears the rungs 35, but if the pull disappears and the carriage tends to run uncontrollably down the support member 11, the safety hook or catch is automatically swung or otherwise moved down between the side rails 12 to a position in which it engages the first rung 35 it encounters so that the carriage is immediately arrested.

An important feature of the hoisting device according to the invention is to be found in the incorporation of the winch in the base member. The incorporation of the winch in the base member not only facilitates the erection and disas¬ sembly of the hoisting device as well as its handling, trans¬ portation and storage. It also means that the weight of the winch, which is the heaviest single component of the hoisting device, does not act on the support member. Accordingly, the support member is only acted on by the weight of the carriage and the load.