Lifting hook

1. A lifting hook arranged to grab an object to be lifted by a cylindrical lifting surface formed thereto, the lifting hook having a hook shank, a hook part joining the hook shank and a locking device arranged to lock the lifting hook to the object to be lifted, a mechanical control device being mounted above the hook part to co-operate with the upper surface of the lifting surface for guiding the hook part to a lifting position onto the lower surface of the lifting surface, wherein the lifting surface is a grooved surface and in that the control device is a protrusion which is narrower than the lifting surface and extends forwardly from the hook shank in line with the lateral direction of the hook part, the forward end of the protrusion being provided with a control arm having a lower surface upwardly inclined towards the upper surface of the protrusion and side surfaces tapering towards the tip of the protrusion.

2. A lifting hook according to claim 1 , wherein the lower surface of a protrusion arm extending from the hook shank towards the control arm of the protrusion is slightly downward inclined, this inclination being smaller than the upward inclination of the lower surface of the control arm of the protrusion.

3. A lifting hook according to claim 2 , wherein the locking device is a forced lever mounted on bearings to the hook shank or the control device, the tip of the lever being outside the lifting surface of the object to be lifted in the lateral direction of the hook part and co-operating with a cylindrical locking surface adjacent to the lifting surface, the locking surface diameter being greater than that of the lifting surface, and when the object to be lifted is guided to the hook part, the lever is arranged to pivot by this guiding action and to allow the lifting surface of the object to be lifted to set into the hook part, whereas when the object to be lifted is in the hook part, the lever thus being in an unloaded state, the tip of the lever is forced to protrude past the centre point of the cylindrical locking surface in the forward extending direction of the hook part for locking the object to be lifted to the hook.

4. A lifting hook according to claim 3 , wherein the forced action of the locking lever is produced by a spring.

5. A lifting hook according to claim 4 , wherein the forced action of the control device is produced by means of a counterweight.

6. A lifting hook according to claim 4 , wherein the locking lever is provided with an actuator for pivoting it towards the hook shank for removing the object to be lifted from the hook part.

7. A lifting hook according to claim 4 , wherein the gripping surface of the hook part and the control device are provided with an electrical sensor arrangement for ensuring the control and the attachment of the hook.

8. A lifting hook according to claim 4 , wherein two hooks are provided and they are attached to the ends of the load-carrying beam meant for the handling of paper rolls in a paper mill, the hooks being configured to grab the paper rolls by the cylindrical lifting surfaces of the cylindrical reeling shafts.

9. A lifting hook according to claim 3 , wherein the locking lever is provided with an actuator for pivoting it towards the hook shank for removing the object to be lifted from the hook part.

10. A lifting hook according to claim 9 , wherein the gripping surface of the hook part and the control device are provided with an electrical sensor arrangement for ensuring the control and the attachment of the hook.

11. A lifting hook according to claim 3 , wherein the forced action of the control device is produced by means of a counterweight.

12. A lifting hook according to claim 3 , wherein the gripping surface of the hook part and the control device are provided with an electrical sensor arrangement for ensuring the control and the attachment of the hook.

13. A lifting hook according to claim 3 , wherein two hooks are provided and they are attached to the ends of the load-carrying beam meant for the handling of paper rolls in a paper mill, the hooks being configured to grab the paper rolls by the cylindrical lifting surfaces of the cylindrical reeling shafts.

14. A lifting hook according to claim 2 , wherein the forced action of the control device is produced by means of a counterweight.

15. A lifting hook according to claim 14 , wherein the locking lever is provided with an actuator for pivoting it towards the hook shank for removing the object to be lifted from the hook part.

16. A lifting hook according to claim 14 , wherein the gripping surface of the hook part and the control device are provided with an electrical sensor arrangement for ensuring the control and the attachment of the hook.

17. A lifting hook according to claim 2 , wherein the gripping surface of the hook part and the control device are provided with an electrical sensor arrangement for ensuring the control and the attachment of the hook.

18. A lifting hook according to claim 2 , wherein two hooks are provided and they are attached to the ends of the load-carrying beam meant for the handling of paper rolls in a paper mill, the hooks being configured to grab the paper rolls by the cylindrical lifting surfaces of the cylindrical reeling shafts.

19. A lifting hook according to claim 1 , wherein the gripping surface of the hook part and the control device are provided with an electrical sensor arrangement for ensuring the control and the attachment of the hook.

20. A lifting hook according to claim 1 , wherein two hooks are provided and they are attached to the ends of the load-carrying beam meant for the handling of paper rolls in a paper mill, the hooks being configured to grab the paper rolls by the cylindrical lifting surfaces of the cylindrical reeling shafts.