Device for hoisting and lowering a load

Abstract

 A device for hoisting and lowering a load comprises driving (13, 14), coupling (5, 6) and winding means (1, 2, 3), wherein at the start of the hoisting operation, the driving means (13, 14) and the coupling means (5, 6) undergo an axial displacement relative to each other such that a coupling between the driving means (13, 14) and the winding means (1, 2, 3) becomes possible thereby, and wherein at the start of the lowering operation, an uncoupling between these driving means (13, 14) and the winding means (1, 2, 3) is effected. A locking member (16) is present for locking the coupling means (13, 14) before the driving (13, 14) and coupling means (5, 6) are axially displaced relative to each other to enable a coupling between the driving (13, 14) and winding means (1, 2, 3), and for undoing this locking when the coupling is effected before the load is hoisted.

Description

[0001] The present invention relates to a device for hoisting and lowering a load, in particular a winch, comprising driving, coupling and winding means, wherein at the start of the hoisting operation by the driving means, the driving means and the coupling means undergo an axial displacement relative to each other such that a coupling between the driving means and the winding means becomes possible, and wherein at the start of the lowering operation by the driving means, an uncoupling between the driving means and the winding means is effected, the coupling means comprising a locking member which, after the driving means and the coupling means are displaced in axial direction relative to each other over a defined distance, automatically releases the coupling means to effect said coupling, the uncoupling taking place through a locking of the coupling means by the locking member and through an opposite axial movement of the driving means relative to the coupling means.

[0002] Such device is known from German patent specification 860 854. When in this known device the load has been hoisted and, subsequently, considerable changes occur in the load, there is a substantial chance that the winding means start to slip and the load comes down all the same. Such a situation occurs in particular in, for instance, a claw-treating device for trimming the hooves of cows. Such claw-treating device typically comprises a turn-up winch for moving a leg of the cow upwards. When the animal with the lifted leg suddenly gives a strong tug at the winch cable, a considerable load increase occurs all at once, with the risk that, as mentioned above, the winding means start to slip and the animal's leg comes down, which entails the risk of the person attending to the animal's claws getting injured. Hence, the winch should be capable of taking a sudden load increase. This could perhaps be possible by giving the winch a considerably larger and heavier construction. However, in view of the fact that in a claw-treating device, both a foreleg turn-up winch and a hindleg turn-up winch are present, such overdesign leads to an unattractive and relatively costly construction.

[0003] The object of the invention is to remove the above drawbacks or at least limit them substantially, and to provide a device for hoisting and lowering a load which is resistant to a suddenly occurring increase of the load, without this device having an appreciably heavier and larger design.

[0004] To that end, in accordance with the invention, the device as described in the preamble is characterized in that a locking member is present for locking the coupling means before the driving means and the coupling means are axially displaced relative to each other to enable a coupling between the driving means and the winding means, and for undoing this locking when the coupling is effected before the load is hoisted. This allows having the coupling take place with a force much greater than would be the case without this measure, as a result of which, when a load has been hoisted and is retained in this hoisted position, the chance of slipping of the winding means is considerably reduced.

[0005] After the uncoupling, lowering can take place under the weight of the load. Should the lowering operation have to be slowed down, an opposite axial movement of coupling means and driving means, and accordingly a coupling between driving means and winding means, can again be established through a rotation of the driving means in the relevant direction.

[0006] The axial movement can in particular be realized in that the coupling means comprise a pawl wheel which is rotatable in the hoisting direction only, and, fixedly connected thereto or forming a whole therewith, a first threaded bush having an external screw thread engaging the internal screw thread of a second threaded bush which is connected to the driving means and concentrically provided around the first threaded bush, wherein the axial movement of the two threaded bushes is bounded relative to each other by friction plates connected to the winding means, and wherein the locking member can be brought into engagement with the pawl wheel against pressure of a spring. These friction plates are fixedly mounted on a windlass forming part of the winding means, while between these friction plates, the coupling means and the second threaded bush are axially movable relative to each other.

[0007] In a preferred embodiment, a return pawl is present, engaging the pawl wheel under the pressure of a spring, the pawl wheel being blocked by the return pawl as soon as the frictional force exerted by the pawl wheel and the second threaded bush on the relevant friction plates becomes less than the force exerted by the spring together with the force of the load suspending from the winding means.

[0008] The locking member mentioned can also be used for blocking the pawl wheel when the second threaded bush is being fixedly clamped against the pawl wheel as a consequence of an unduly far axial movement in the relevant direction, in order that through an opposite movement of the second threaded bush, it may come loose from the pawl wheel.

[0009] The invention does not merely relate to a device for hoisting and lowering a load, but also to a claw-treating device for trimming the hooves of animals, in particular cows, wherein means are present for securing the forelegs and/or hindlegs and, if necessary, the bellyband of an animal arranged in this treating device. According to the invention, these means are formed by the aforesaid hoisting and lowering device.

[0010] The invention will presently be specified with reference to the accompanying drawings, wherein:

Fig. 1 schematically shows a longitudinal section of the device according to the invention; while in

Fig. 2, a cross section of the locking member is shown, likewise schematically.

[0011] In the present exemplary embodiment, the winding means are formed by a windlass 1 on which, at a particular distance from the end of this windlass, a friction plate 2 is fixedly mounted, for instance through welding. A second friction plate 3 can be provided on the end of the windlass 1, by means of, for instance, a grooved pin 4. Provided around the windlass 1 and adjoining the friction plate 2 is a toothed pawl wheel 5, rotatable in only one direction. The pawl wheel 5 can only be rotated in the direction in which a load can be hoisted. To this pawl wheel 5, a first threaded bush 6, further referred to as pawl wheel threaded bush, is fixedly connected, for instance through welding. The pawl wheel 5 is rotatable in a pawl housing 8 comprising a cover 7. In this pawl housing, a return pawl 10 is located, which is under pressure of a spring 9 and which can engage the pawl wheel 5. For that purpose, the return pawl 10 is located in the hollow space of a first projecting housing part 11, which housing part is closed by a bolt 12. Also by means of this bolt, the required bias is imparted to the spring 9 resting against the return pawl 10. The pawl wheel 5 and the return pawl 10 form a locking member to enable blocking a movement of the pawl wheel or allowing a movement in one direction of rotation only.

[0012] Provided around the pawl wheel threaded bush is a second threaded bush 13, further referred to as drive wheel threaded bush. To this threaded bush, a drive wheel 14 is fixedly connected, for instance through welding. In a manner not further shown, this drive wheel can be driven manually, with or without the interposition of a chain or belt, or by a motor via all kinds of possible transmission means. By rotation of the drive wheel 14 relative to the pawl wheel 5, the external screw thread of the pawl wheel threaded bush 6 and the internal screw thread of the drive wheel threaded bush 13 rotate such that an axial movement of the drive wheel 14 relative to the pawl wheel 5 can be realized. However, this axial movement is bounded by the friction plates 2 and 3.

[0013] The pawl housing 8 further comprises a second projecting housing part 15, in the hollow space of which a locking member 16 is arranged, under pressure of a spring 17. Under conditions to be mentioned hereinbelow, it is useful to have the locking member 16 engage between the teeth of the pawl wheel 5 by depressing this locking member 16 against the pressure of the spring 17.

[0014] The operation of the above-described device is as follows:

[0015] When a load is to be hoisted, the locking member is depressed first, so that the pawl wheel 5 is blocked. Next, the drive wheel 14 is rotated in a direction such that an axial movement of the drive wheel threaded bush 13 over the pawl wheel threaded bush 6 causes the drive wheel 14 to be pressed against the friction plate 3. This involves the friction plate 2 being fixedly pressed against the pawl wheel such that this friction plate and the pawl wheel form as it were a rigid whole. After that, the locking member is released and the pawl wheel is released for rotation in the direction indicated by an arrow A in Fig. 2. The force exerted on the friction plates is then considerably greater than the force exerted by the spring 9 together with the force of the load suspending from the windlass 1, and the load can be hoisted up. If the drive wheel is subsequently fixed, slipping of the windlass 1 will occur under exceptional circumstances only, due to the fixed clamping action between the friction plate 2 and the pawl wheel 5.

[0016] However, if the drive wheel 14 is released so that an uncoupling can take place, the return pawl 10 slips into the pawl wheel 5 under pressure of the spring 9. The pawl wheel 5 is then fixed in the actually fixedly arranged pawl housing 8, as a result of which the drive wheel 14 remains stationary, too, as well as the windlass 1, because the windlass 1 is still coupled to the pawl wheel 5 and the drive wheel threaded bush 13.

[0017] When the lowering operation is started, the drive wheel should be rotated slightly in the other direction, i.e. in the direction in which the drive wheel 14 and the pawl wheel 5 are axially moved towards each other. The windlass 1 is then uncoupled from the drive wheel 14. The pawl wheel 5 is still fixed in the pawl housing 8 and by not rotating the drive wheel 14 any further, the windlass 1 can rotate freely and the lowering of a load takes place under the load's own weight. If the lowering movement is too fast, it can be slowed down by rotating the drive wheel 14 in the direction at which the drive wheel and the pawl wheel move apart axially, whereby the non-rotating pawl wheel 5 and the drive wheel threaded bush 13 are pressed against the friction plates 2 and 3.

[0018] When at the start of the lowering operation, the drive wheel is rotated back too far, i.e. further than necessary for releasing the windlass 1, the drive wheel threaded bush 13 can jam against the pawl wheel 5 and perhaps to such an extent that rotation of the drive wheel 8 in the direction required for hoisting involves the pawl wheel moving along and hence not coming loose from the drive wheel threaded bush 13. For this reason, the pawl wheel can be secured by depressing the locking member 16 once again. Rotation of the drive wheel in the direction required for hoisting then causes the drive wheel threaded bush to come loose from the pawl wheel. Hence, the locking member 16 has a double function, while, however, the use of the locking member before the start of the hoisting operation proves to be essential.

[0019] The device described hereinabove can in particular be used in a favorable manner in those cases where hoisting takes place through operation of the driving means and where lowering takes place under the influence of the load's own weight, in which case, however, braking means must be present to keep the lowering action under control. Owing to the simple and, accordingly, compact construction of the device, it is particularly suitable for being utilized in all kinds of places. In particular, the device is suitable for being used in claw-treating devices for trimming the hooves of cows. In such, typically mobile treating devices, usable throughout the country, the forelegs and/or hindlegs and, if necessary, the bellyband must be secured to prevent a person tending the hooves from being injured by kicks from the animal. By using the invention, such treating device can be provided with a hindleg turn-up winch, a bellyband turn-up winch and a foreleg turn-up winch. However, it will be understood that many other uses of a device according to the invention are possible.

Claims

1. A device for hoisting and lowering a load, in particular a winch, comprising driving (13, 14), coupling (5, 6) and winding means (1, 2, 3), wherein at the start of the hoisting operation by the driving means (13, 14), the driving means (13, 14) and the coupling means (5, 6) undergo an axial displacement relative to each other such that a coupling between the driving means (13, 14) and the winding means (1, 2, 3) becomes possible thereby, and wherein at the start of the lowering operation by the driving means (13, 14), an uncoupling between the driving means (13, 14) and the winding means (1, 2, 3) is effected, characterized in that a locking member (16) is present for locking the coupling means (13, 14) before the driving means (13, 14) and the coupling means (5, 6) are axially displaced relative to each other to enable a coupling between the driving means (13, 14) and the winding means (1, 2, 3), and for undoing said locking when the coupling is effected before the load is hoisted.

2. A device according to claim 1, characterized in that the coupling means (13, 14) comprise a pawl wheel (5) which is rotatable in the hoisting direction only, and, fixedly connected thereto or forming a whole therewith, a first threaded bush (6) having an external screw thread engaging the internal screw thread of a second threaded bush (13) which is connected to the driving means (13, 14) and concentrically provided around said first threaded bush (6), wherein the axial movement of the two threaded bushes (6, 13) is bounded relative to each other by friction plates (2, 3) connected to the winding means (1, 2, 3), and wherein the locking member (16) can be brought into engagement with the pawl wheel (5) against pressure of a spring (17).

3. A device according to claim 2, characterized in that the friction plates (2, 3) are fixedly mounted on a windlass (1) forming part of the winding means (1, 2, 3), while between said friction plates (2, 3), the coupling means (5, 6) and the second threaded bush (13) are axially movable relative to each other.

4. A device according to claim 3, characterized in that a return pawl (10) is present, engaging the pawl wheel (5) under the pressure of a spring (9), the pawl wheel (5) being blocked by the return pawl (10) as soon as the frictional force exerted by the pawl wheel (5) and the second threaded bush (13) on the relevant friction plates (2, 3) becomes less than the force exerted by the spring (11) together with the force of the load suspending from the winding means (1, 2, 3).

5. A device according to claim 2, 3 or 4, characterized in that the locking member (16) is also present for blocking the pawl wheel (5) when the second threaded bush (13) is fixedly clamped against the pawl wheel (5) as a consequence of an unduly far axial movement in the relevant direction, in order that through an opposite movement of the second threaded bush (13), it may come loose from the pawl wheel (5).

6. A claw-treating device for trimming the hooves of animals, in particular cows, wherein means are present for securing the forelegs and/or hindlegs and, if necessary, the bellyband of an animal arranged in said treating device, characterized in that said means are formed by a device according to one or more of the preceding claims.

Drawing