Freewheel coupling device for a spring-loaded operating mechanism for a high-voltage circuit-breaker

1. An operating mechanism for a high-voltage circuit-breaker comprising a coupling device of the freewheel type disposed between a trigger shaft of the operating mechanism and an electrical motor, the coupling device comprising a first friction member linked in motion with the trigger shaft and a second friction member linked in motion with the electrical motor, said friction members being coaxially mounted on a secondary shaft so that when said secondary shaft rotates in a predetermined direction when a spring-loaded mechanism that acts on the device relaxes, it is possible for the second friction member to freewheel about said secondary shaft in said predetermined direction at a speed of rotation that is lower than the speed of rotation of the secondary shaft, it also being possible for said second friction member to be rotated by the motor in said predetermined direction, and to become constrained to rotate with the first friction member so as to recock said spring-loaded mechanism, wherein:

said first friction member has an outer surface of conical shape and comprises a central bore screwed onto said secondary shaft,

the second friction member comprises a peripheral set of teeth meshing with the motor drive shaft and a central bore with an inner conical surface which substantially surrounds the outer conical surface of said first friction member, said first and second friction members being designed so that said first friction member is suitable for being moved over a short axial stroke along the secondary shaft either by being screwed when it becomes constrained to rotate with the second friction member or by being unscrewed when said member freewheels about said secondary shaft,

said first and second friction members remain continuously substantially in abutment one against the other along said secondary shaft,

said first friction member is suitable for acting when it is screwed to exert a pressure on said second friction member, and

said second friction member is suitable for acting under the effect of said pressure to press against an axial abutment on the secondary shaft so as to stop said first friction member moving by being screwed, and so as to rotate said secondary shaft by constraining it to rotate with said first friction member.

2. An operating mechanism according to claim 1 , in which said first friction member is held substantially in abutment against said second friction member by a spring.

3. An operating mechanism according to claim 2 , in which said first friction member is screwed onto a thread formed on the shaft, said thread being reversible.

4. An operating mechanism according to claim 1 , in which said axial abutment is a ball-bearing abutment.

5. An operating mechanism according to claim 1 , in which said first friction member is provided with a peripheral set of teeth meshed with said trigger shaft.

6. An operating mechanism according to claim 1 , in which a conical ring is disposed between the two conical surfaces of said friction members.

7. An operating mechanism according to claim 1 , in which the first friction member has an outer conical surface which is provided with peripheral grooves serving to absorb dust.

8. An operating mechanism according to claim 6 , in which the conical ring is made with polyamide reinforced with glass fiber.

9. An operating mechanism according to claim 3 , in which the thread has four starts with a pitch of about 20 mm per turn, and the secondary shaft has a diameter of about 24 mm.