Driving device for sprocket wheels of chain drives

1. Drive system for chain sprockets of chain drives, preferably for driving chain scraper conveyors or chain-drawn ploughs for underground mining, the system comprising a drive assembly having an asynchronous motor and a gear mechanism, the gear mechanism being an overload gearing having a controllable multiple-disk clutch for overload equalisation with which the force flow between the asynchronous motor and the chain sprocket can be disconnected, wherein the asynchronous motor comprises a frequency converter motor with a motor shaft, and the drive assembly has a two-gear toothed wheel gear mechanism arranged between the motor shaft and the gear mechanism, the two-gear toothed wheel gear mechanism having a starting gear position and a normal gear position.

2. Drive system according to claim 1 , wherein the two-gear toothed wheel gear mechanism is designed as a forward gearing mechanism.

3. Drive system according to claim 1 , wherein the two-gear toothed wheel gear mechanism has a returning transmission gear mechanism with a gear transmission of preferably 1:3 to 1:4 for the starting gear position.

4. Drive system according to claim 1 , wherein the toothed wheel gear mechanism has gear shaft, a drive side central wheel borne in a rotating manner on the gear shaft and an output side central wheel borne in a rotating manner on the gear shaft, and between said central wheels there is arranged a control wheel connected in a torsion-stable manner to the gear shaft, whereby the control wheel can be coupled in a rotating manner by means of a control device to either the drive side or output side central wheel .

5. Drive system according to claim 4 , wherein both central wheels and the control wheel have a toothed section with identical toothing aligned with and adjacent to each other.

6. Drive system according to claim 4 , wherein the control device comprises a control hub which is pushable over the toothed sections of two adjacent toothed wheels of the toothed wheel gear mechanism.

7. Drive system according to claim 6 , wherein the control hub is movable by means of a control fork which can be moved parallel to the gear shaft axis by means of a control rod.

8. Drive system according to claim 4 , wherein the toothed wheel gear mechanism has a casing and wherein the gear shaft is borne on the output side on the gear casing and is supported on the drive side by the drive side toothed wheel which on the drive side is borne in a rotating manner on the gear casing.

9. Drive system according to claim 1 , wherein the toothed wheel gear mechanism has a gear casing and a secondary shaft borne in a rotating manner on the gear casing, the secondary shaft having a first gear toothing engaging with the drive side central wheel, and a second gear toothing engaging in the output side central wheel .

10. Drive system according to claim 9 , wherein at least the first gear toothing is part of a single wheel connected in a torsion-stable manner to the secondary shaft .

11. Drive system according to claim 2 , wherein the toothed wheel gear mechanism comprises a spur gearing.

12. Drive system according to claim 4 , wherein the drive side central wheel is designed as a bushing and/or is internally provided with a hub connection for the motor shaft.

13. Drive system according to claim 2 , wherein the frequency converter motor and the toothed wheel gear mechanism are arranged in a common casing whereby the drive side central wheel is preferably arranged on the motor shaft.

14. Drive system according to claim 1 , wherein the frequency converter motor is provided with a motor casing, a stator with stator windings, a rotor with frequency converter control and a motor shaft rotating with the rotor, the shaft having a motor flange side adjacent the gear mechanism and a rear side at the opposite end, both the motor flange side and the rear of the motor shaft being borne on the motor casing, the motor shaft being designed as a hollow shaft, the axial boring of which is penetrated by a torsion rod , which is moveably coupled therewith only at the rear end of the hollow shaft.

15. Drive system according to claim 14 , wherein the torsion rod passes through the axial boring and/or the motor casing in a contact-free manner on the motor flange side.

16. Drive system according to claim 14 , wherein the torsion rod can be inserted and pushed through the hollow tube from its rear end.

17. Drive system according to claim 14 , wherein the motor flange side end of the torsion rod has a pinion, toothing or a shaft connection, the outer diameter of which is smaller than the minimum internal diameter of the axial boring.

18. Drive system according to claim 17 , wherein the rear end of the torsion rod has a pinion, hub connection means or hub connection toothing, the external diameter of which is greater than the motor flange side end of the torsion rod and the inner diameter of the axial boring.

19. Drive system according to claim 14 , wherein at the rear end of the torsion rod there is a nominal breakage point and in that fastening means for an assembly/dismantling aid for the torsion rod are arranged between the nominal breakage point and the motor flange end.

20. Drive system according to claim 19 , wherein the fastening means has an axial threaded boring in a face side of the torsion rod.

21. Drive system according to claim 14 , wherein the frequency converter control is arranged in a control box integrated into the motor casing.

22. Drive system according to claim 14 , wherein the motor flange side end of the torsion rod projects from the motor casing.