GB2235916A - Hand tackle - Google Patents

Abstract

A hand tackle comprises an internally toothed pulley wheel (4) for a suspension cable (8), and a hand driven driving shaft (19) carrying a pinion (5) that meshes directly with the toothed pulley wheel (4). The tackle may be used for raising and lowering a hanging bridge for external building maintenance Instead of meshing teeth, friction contact may be employed. <IMAGE>

Description

HAND TACKLE This invention relates to a hand tackle which can move a load along a vertically suspended cable. The invention has particular though not exclusive application to raising and lowering a so-called hanging bridge, for example for maintenance works to the outside of a building.

A previously proposed hand tackle used for such work principally comprises a solid heavy pulley wheel that on its edge has a gear rim with internal teeth and wherein a sun wheel is mounted on a driving shaft situated in the centre of the toothed pulley wheel and drives the toothed pulley wheel by way of a plurality of planet wheels.

Because of such solid toothed pulley wheel and the planet wheels such a tackle is heavy and the frictional resistance of the tackle is increased. A major disadvantage is still further that the pulley wheel and more especially the teeth of the gear rim are very difficult to manufacture since the pulley wheel is a solid wheel which for example does not allow simple manufacture of the teeth and these can only be produced by slotting.

With another previously proposed tackle of a similar type the toothed pulley wheel comprises a ring provided with an internal toothing which is mounted rotatably in a gear box by means of ball bearings. The drive occurs by means of a large number of toothed wheels including a sun wheel and two planet wheels.

Due to the complex structure such a tackle is difficult to manufacture, has a high internal resistance and is very heavy.

According to the invention there is provided a hand tackle comprising a gear box and a toothed pulley wheel mounted in the gear box and to have a suspension cable wrapped therearound, the toothed pulley wheel is ring shaped and comprises a gear rim with the internal teeth mounted rotatably in the gear box by means of bearings, and a driving shaft mounted on bearings in the gear box carries a pinion that meshes directly with the toothed pulley wheel to form a gear transmission.

Such a hand tackle can be lightweight, simple, easy and relatively inexpensive to manufacture and can have a low internal resistance.

Such a hand tackle can give a very efficient distribution of power.

Although the specification and claims refer to toothed wheels it should be appreciated that the same results and advantages can be obtained with a hand tackle according to the invention utilising friction wheels.

Through the special bearing arrangement of the gear rim it is obtained at the same time that this allows a certain, be it of course small, angular adjustment without this being disadvantageous or inconvenient for the good operation of the hand tackle.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Figure 1 shows a schematic front view of a first embodiment of a hand tackle according to the invention; Figure 2 shows a section taken on line II-II in Figure 1; Figure 3 shows on a larger scale a part that is indicated F3 in Figure 2; and -Figure 4 shows another embodiment of a hand tackle according to the invention.

Referring to Figures 1 and 2, a hand tackle has a casing 1 with therein an in itself known safety mechanism 2 and a gear box 3 in which a toothed pulley wheel ii is driven by a pinion 5.

The hand tackle is suspended in relation to two cables namely a safety cable 6, which extends vertically via a guide tube 7 through the hand tackle, and an actual suspension cable 8 which goes more centrally through guide tubes 9, is wound once around the toothed pulley wheel 4 and emerges from the hand tackles laterally where it is supported by a guide 10. In its turn a hanging bridge (not shown) is attached by means of a fixed connection 11 to one or more of these hand tackles.

The toothed pulley wheel 4 is formed by a gear rim 12 with internal teeth 13 which is mounted in the gear box 3 by means of two ball bearings 14 working together with the outer circumference of the pulley wheel and has a V-shaped groove 15 extending over its entire outer circumference, located between the two ball bearings 19 and to receive the suspension cable 8. A small wheel 16 with an outer circumference 17 shaped to suit the suspension cable 8 is mounted on bearings in a pressure element 18 and presses the suspension cable 8 into the V-shaped groove 15.

The toothed pulley wheel 4 is driven by the much smaller pinion 5 that is fixed on a driving shaft 19 which is mounted on bearings in the gear box 3 by means of two ball bearings 20 near to the location where the suspension cable 8 runs onto the toothed pulley wheel 4.

The driving shaft 19 itself extends to outside the gear box 3 where a respective crank 21 with a grip 22 is mounted on each protruding extremity.

Between one of the two cranks 21 and the gear box 3 a blocking mechanism is installed cbmprising a ratchet wheel 23 and a cooperating pawl 24. With the same objective a braking mechanism is also provided comprising a sleeve 25 fixed on the driving shaft, a sleeve 27 which can be screwed over the driving shaft 19 by means of a rod 26 and brake rings 28 between them which grip onto a fixed ring. The fixed ring can for example be the ratchet wheel 23.

A freewheel clutch could possibly also be built in for this purpose.

The safety mechanism 2 can be formed by two brake blocks 29 which by means of a not shown, but in itself known, centrifugal mechanism can be clamped against the safety cable 6, whereby the aforementioned centrifugal mechanism is driven by the movement of the safety cable 6 through the hand tackle.

In use the safety cable 6 is suspended vertically next to the suspension cable 8 for example from the roof of a building.

Through rotation of the cranks 21 in the direction of the arrow 30, the pinion 5 and the toothed pulley wheel 4 also rotate, the toothed pulley wheel with considerable speed reduction, and the toothed pulley wheel 4 travels upward over the suspension cable 8.

The cable 8 is thereby firmly drawn into the groove of the toothed pulley wheel 4 so that it does not slip through.

Before the cranks 21 are released the sleeve 27 is screwed toward the sleeve 25 by means of the rod 26, whereby the ratchet wheel 23 is clamped fast between the sleeves 25, 27. The hand tackle will then remain suspended in position on the suspension cable 8 since the pawl 24 prevents rotation in the opposite direction. In order to move downward again the sleeve 27 must be unscrewed such that the brake rings 28 can slide over the ratchet wheel whereby if desired they can provide for some braking action during the downward movement.

The safety cable 6 provides an extra security device. If the hand tackle were to roll uncontrolled downward over the suspension cable 8 or if the suspension cable 8 were to break or come loose, the centrifugal mechanism would press the brake blocks 29 against the safety cable 6 and by so doing bring the hand tackle and thereby the hanging bridge to a standstill.

The above described hand tackle is almost symmetrically produced through which it is very easy and simple to use. In any case it hangs almost in equilibrium on the suspension cable 8 and the driving shaft 19 is also situated close to the suspension cable 8.

Because of the direct drive of the toothed pulley wheel 4 without intervention of planet wheels for example there is very little frictional loss and the cranks 21 rotate in the most logical direction, namely the same direction as the toothed pulley wheel 4 that as it were travels over the suspension cable 8.

The simple construction of the above described hand tackle can bring the advantage that it is inexpensive to manufacture. Also the special form of the toothed pulley wheel Li as an open ring, furthermore allows in particular that the teeth 13 on this toothed pulley wheel 4 can be manufactured much more easily and inexpensively, for example by simple cutting.

In Figure 4 a variant is shown of the hand tackle wherein the safety mechanism 2 is assisted by a second safety mechanism 31 that acts on the cable 8 and an eccentrically operating disc 32 which presses on the cable 8 when standing still. When descending, the disc 32 must be manually freed from the cable 8.

In Figure 4 it is indicated that the brake blocks 29 which with undesired descent act on the cable 6, are assisted by a spring 33.

Also in Figure 4 it is illustrated that the small wheel 16 is pressed onto the cable 8, on the one hand, under influence of the weight of the hanging bridge which through intervention of a rod 34 in a hinge point 35 is attached to the pressure element 18, and on the other hand, through intervention of a spring 36.

Claims (11)

1. A hand tackle comprising a gear box and a toothed pulley wheel mounted in the gear box and to have a suspension cable wrapped therearound, the toothed pulley wheel is ring shaped and comprises a gear rim with the internal teeth mounted rotatably in the gear box by means of bearings, and a driving shaft mounted on bearings in the gear box carries d pinion that meshes directly with the toothed pulley wheel to form a gear transmission.

2. A hand tackle according to claim 1, in which the pinion meshes with the toothed pulley wheel adjacent the location at which the suspension cable rolls onto the toothed pulley wheel during upward movement.

3. A hand tackle according to claim 1 or claim 2, in which one extremity of the driving shaft extends to a position outside the gear box and is provided there with a crank.

LI. A hand tackle according to any one of the preceding claims, in which a ratchet wheel that works together with a pawl attached to the gear box is mounted on the driving shaft.

5. A hand tackle according to any one of the preceding claims, in which a fixed sleeve is mounted on the driving shaft and in relation to this sleeve opposite the driving shaft a further sleeve is movable by screwing, and each of the sleeve and the further sleeve carries a brake ring with the brake rings opposite each other and having therebetween a ring connected to the gear box.

6. A hand tackle according to claim 5 when appendant to claim 4, in which the ring situated between the two brake rings forms the ratchet wheel.

7. A hand tackle according to any one of the preceding claims, in which guides are provided in the hand tackle for a safety cable.

8. A hand tackle according to any one of the preceding claims, in which a second safety mechanism is provided that is principally formed by an eccentric disc which acts on the cable when the hand tackle is stationery.

9. A hand tackle according to any one of the preceding claims, in which a hanging bridge is suspended via a rod and a hinge point from a pressure element that itself is hingedly attached to the casing of the hand tackle and that has a freely rotatable small pressure wheel that, at the location of the V-shaped groove of the toothed pulley wheel, works together with the cable.

10. A hand tackle according to claim 9, in which the pressure element is connected by means of a spring to the housing of the hand tackle, such that the spring firmly presses the pressure element, respectively the small pressure wheel, toward the groove, respectively against the cable in this groove.

11. A hand tackle substantially as hereinbefore described and illustrated with reference to the accompanying drawings.