GB2148845A - Self-closing grapple with locking safety device - Google Patents

Abstract

The invention relates to a self-closing grapple (110) equipped with a safety device ensuring locking of the grapple when a load is carried. The axle (124) on which the arms (120) pivot on the vertical stem (112) is carried by a tubular component (136) which is normally integrally fixed to the stem by locking means (134) preventing any operation of the grappler. The locking means (134) incorporate a lever (138) fitted with a counterweight (142) normally applying a plate (146) fixed integrally to the stem against a skid (148) fixed integrally to the component (136) under the effect of at least one cam. <IMAGE>

Description

SPECIFICATION Self-closing grappler with locking safety device for carrying a load The present invention relates to a self-closing grappler intended for carrying a load and incorporating a safety device ensuring locking of the grappler in a closed position.

As shown by way of example in Figure 1, in the case of a grappler 10 intended to carry a drum F, the self-closing grapplers according to the prior art consist generally of a vertical stem or tie beam 12 whose upper end is intended to be suspended from a handling apparatus such as a rolling bridge by a hook 14. The lower end of the stem 12 carries an axle 16 around which are mounted pivoting two connecting rods 18. The grappler 10 also incorporates two gripping arms 20, articulated via one of their ends to the opposite end of each of the connecting rods 18 through the intermediacy of two axles 22 and whose central part is mounted to pivot on an axle 24 carried by the stem 12 above the axle 16. The lower end of each of the arms 20 supports, pivoting around an axle 26, a gripping jaw 28 the shape of which is adapted to the shape of the drum Fto be seized.

In the grappler which has just been described in outline with reference to Figure 1, the gripping and releasing motion of the grappler can be obtained only on condition that each of the triangles formed by an arm 20, the corresponding connecting rod 18 and the stem 12 can be distorted. For this purpose, the axle 24 can consist of a drumhead mounted to slide along the vertical axis of the stem 12.

Under these conditions, the operation of the self-closing grappler according to the prior art is as follows.

The grappler being suspended from the hook 14, the operators separate the jaws 28 of the grappler by actuating the arms 20. The grappler is then placed over the drum F in the position shown in Figure 1, in which it can be seen that each of the arms 20 incorporates for this purpose a stop 30. In this position, each of the stops 30 bears on the top end of the drum F. When the hook 14 lifts, the stem 12 pushes back the two connecting rods 18 which in their turn actuate the arms 20 to close the grappler automatically again and to seize the drum. When the drum F is placed on the ground again, the grappler is no longer loaded and the stem 12 continues to descend, which results in the grappler being automatically opened and the drum released.

The known self-closing grappler which has just been described with reference to Figure 1 is such that the clamping of the load is produced by gravity under the action of the load itself, when the latter is raised. Thus, the closing of the grappler is stronger in proportion to the weight of the load.

However, this known grappler has the disadvantage that if, during handling, particularly while descending, the load encounters an obstacle which is not its resting place, it runs the risk of being accidentally unhooked.

The subject of the present invention is precisely a self-closing grappler equipped with a locking system which enables it to remain closed over the load, even when the latter encounters an obstacle while descending.

For this purpose and in accordance with the invention, a self-closing grappler for carrying a load is proposed, incorporating a vertical stem capable of being suspended from a handling apparatus, at least two gripping arms articulated around at least one axle carried by the said stem and at least two connecting rods each articulated on the said stem and on a corresponding gripping arm, the said axle being mounted so as to be capable of sliding vertically relative to the stem, so that each gripping arm forms, with the corresponding connecting rod and with the said stem, distortable triangle ensuring an automatic clamping of the load between the gripping arms when the stem is raised, characterised in that locking means are provided between the said axle and the stem carrying it, in order to prevent any distortion of the said distortable triangle when they are actuated.

Preferably, locking means are normally actuated by gravity and they incorporate at least one cam actuated by a lever carrying a counterweight which normally keeps the cam in a locking position.

In a preferred embodiment of the invention, the axle of articulation of the gripping arms on the vertical stem is integrally fixed to a component mounted so as to be capable of sliding vertically relative to the stem. The cam can then be mounted to pivot on the said component and co-operate with a plate integrally fixed to the stem, to apply this plate normally against a skit fixed integrally to the component, under the effect of the counterweight.

In order that the counterweight acts continuously on the lever to apply the cam in a locking position, the said component preferably carries a stop restricting the movement of the lever.

A description will now be given, by way of a non-restrictive example, of a particular embodiment of the invention with reference to the attached drawings, in which: Figure 1 already described, is a front view of a self-closing grappler according to the prior art, Figure 2 is a view comparable to Figure 1 showing a preferred embodiment of a self-closing grappler equipped with a system for locking the grappler in a closed position in accordance with the invention, Figure 3 is a view in cross-section along the line A-A of Figure 2, and Figure 4 is a view in cross-section along the line B-B of Figure 2.

In Figures 2 to 4, the components which are comparable to the components of the known grappler described earlier with reference to Figure 1 have been indicated by the same reference numbers increased by 100.

Thus, in the grappler 110 shown in Figure 2, the vertical stem 112 can be recognised, suspended by an opening (not shown) provided for this purpose at its upper end, from the hook 114 of a rolling bridge, or any similar handling device. The stem 112 carries at its lower end the horizontal axle 116 on which are articulated the connecting rods 118. These connecting rods 118 extend upwards on either side of the stem 112, substantially at 45" relative to the latter, and at their end they carry the horizontal axles 122 which are parallel to the axle 116, and on which are articulated the gripping arms 120.

The arms 120 extend downwards symmetrically relative to the vertical axis of the stem 112, substantially at 60 relative to the latter. They are articulated in their median part on the stem 112 through the intermediacy of a common horizontal pivoting axle 124 which is also parallel to the axles 116 and 122.

Also identified in Figure 2 are the jaws 128 which are mounted pivoting about horizontal axles 126 parallel to the axles 116, 122 and 124, on the lower ends of the gripping arms 120 and whose shape is adapted to the shape of the load to be seized such as that of the drum F.

Each of the arms 120 also carries a stop 130 intended to come to bear on the upper face of the drum F, when the grappler is placed over the drum and ready to be raised as shown in Figure 2. In addition, in orderto facilitate the handling of the grappler, each arm 120 carries a handle 152 on its lower end.

As mentioned earlier in connection with the known grappler shown in Figure 1, the clamping and releasing motions of the grappler require distortion of the triangles formed by each of the arms 120 with the corresponding connecting rod 118 and the stem 112. This result is produced by permitting a movement of the axle 124 for pivoting the arms relative to the stem 112, along the vertical axis of the latter. In practice, it can be seen in Figure 2 that this movement is made possible by the presence of an oblong vertical opening or light 132 formed in the stem 112 and in which the axle 124 is received.

According to the invention, the self-closing grappler of Figure 2 is also equipped with locking means 134 intended to prevent the distortion of the triangles formed by the arms 120, the connecting rods 118 and the stem 112 when they are in a locking position.

Preferably these locking means 134 are designed so that they normally prevent any distortion of these triangles and so that they must be unlocked when it is intended to manoeuvre the grappler.

In practice, and as shown in greater detail in Figures 3 and 4, the axle 124 is mounted on a tubular component or body 136 and the locking means 134 are placed between this component and the stem 112. More precisely, the component 136 is arranged coaxially around the stem 112 over the major part of the height of the latter and incorporates open slots 136a at its lower end for the passage of the arms 120 and of the connecting rods 118. The locking means 134 are provided between the upper end of the component 136 and the stem 112.

In the preferred embodiment shown in Figures 2 and 3, the locking means 134 incorporate a lever 138 mounted pivoting around a horizontal axle 140, on the component 136 and carrying a counterweight 142 at its end. The axle 140 is situated beside the stem 112 and carries one or two identical cams 144, as shown in Figure 3, which are eccentric relative to the axle 140 and are arranged on either side of the stem 112. The shape of the cams 144 is designed so as to apply a Plate 146 fixed integrally to the stem 112 against a skid 148 integrally fixed to the component 136 and arranged opposite the axle 140 relative to the stem 112, when the lever 138 is lowered towards the horizontal, in the direction of the arrow F1 in Figure 2.

By virtue of this arrangement, it can be imagined that the counterweight 142 acts by gravity on the LeYer 138, to apply normally the plate 146 against the skid 148 under the effect of the cams 144. Any movement ofthe axle 124 in the oblong light 132 is thus normally impossible. When a load such as a drum F is caught in the grappler, any accidental opening of the grappler is thus prevented, even when the drum encounters an obstacle while descending.

When it is intended to bring the grappler into operation, either to take a load or, on the contrary, to release it, it is thus necessary to lift the lever 138 in the direction of the arrow F2 towards the position shown by a dot-and-dash line in Figure 2. The axle 124 can then slide inside the light 132 and the operation of the grappler is the same as that of the grappler according to the prior art described with reference to Figure 1.

In order to prevent the lever 138 from pivoting in the direction of the arrow F2 beyond the position at which it is brought back automatically by the counterweight 142 towards its clamping position in the direction of the arrow F1,the component 136 preferably carries a stop 150 situated above the axle 140.

The invention is not restricted, of course, to the embodiment which has just been described by way of example, but covers all its alternative forms. In particular, it will be understood that the invention may be applied to self-closing grapplers having different structures and particularly with claws incorporating three or four gripping arms, and to grapplers in which the arms and the connecting rods are arranged differently. Similarly, it will be understood that the means for locking the axle 124 within the light 132 can differ from the means described. In particular, the component 136 can be eliminated, the locking means then acting directly between the axle 124 and the stem 112. The frictional locking of the skid 148 against the plate 146 can also be replaced, in a grappler similar two the grappler described, by rack-type locking, the plate 146 and the skid 148 then incorporating facing toothings which engage in each other to provide the locking. In addition, the actuation of the locking means may be other than manual and by gravity, but hydraulic, pneumatic, magnetic or other.

Claims (6)

1. A self-closing grapplerforcarrying a load, incorporating a vertical stem capable of being suspended from a handling apparatus, at least two gripping arms articulated around at least one axle carried by the said stem and at least two connecting rods each articulated on the said stem and on a corresponding gripping arm, the said axle being mounted so as to be capable of sliding vertically relative to the stem, so that each gripping arm forms, with the corresponding connecting rod and with the said stem, a distortable triangle ensuring an automatic clamping of the load between the gripping arms when the stem is raised, wherein locking means are provided between the said axle and the stem carrying it, in order to prevent any distortion of the said distortable triangle when they are actuated.

2. A self-closing grappler according to claim 1, wherein the locking means are normally actuated by gravity.

3. A self-closing grappler according to claim 2, wherein the locking means incorporates at least one cam actuated by a lever carrying a counterweight which normally keeps the cam in a locking position.

4. A self-closing grappler according to claim 3, wherein the said axle is mounted on a component mounted so as to be capable of sliding vertically relative to the stem and in that the cam is mounted to pivot on the said component and cooperate with a plate integrally fixed to the stem to apply this plate normally against a skid fixed integrally to the said component, under the effect of the counterweight.

5. A self-closing grappler according to claim 4, wherein the said component carries a stop restricting the movement of the lever so that the counterweight acts permanently on the lever to apply the cam into a locking position.

6. A self-closing grappler substantially as hereinbefore described with reference to, and as illustrated in, Figures 2 to 4 of the accompanying drawings.