Winch equipped with a variable torque limiter
A winch includes a rotary drum, a cable which can be wound on the drum in multiple layers, and a brake for braking the rotation of the drum, the brake being calibrated to permit the rotation of the drum beyond a variable torque which decreases as the length of the cable wound on the drum increases.
1. A winch comprising a frame, a drum which can rotate in relation to the frame about an axis of rotation, a cable which can be wound on the drum in multiple layers, a brake for braking the rotation of the drum, the brake being calibrated to permit the rotation of the drum beyond a variable torque which decreases as the length of the cable wound on the drum increases, and a mechanism for adjusting the torque exerted by the brake comprising a screw-nut system of which the nut is driven in rotation with the drum, and of which a translational movement of the screw driven by the nut is configured to adjust the torque exerted by the brake.
2. The winch as claimed in claim 1 , wherein the brake comprises at least one first plate which is movable in translation in relation to the frame along the axis of rotation of the drum and is prevented from rotating in relation to the frame about the axis of rotation of the drum, at least one second plate which is prevented from rotating in relation to the drum about the axis of rotation of the drum, a compression element designed to compress the first plate against the second plate along the axis of rotation of the drum, and wherein the adjusting mechanism is configured to adjust the compression of the compression element depending on the rotation of the drum.
3. The winch as claimed in claim 2 , wherein the compression element is a first elastic element which exerts a force proportional to its length (L) along the axis of rotation of the drum.
4. The winch as claimed in claim 2 , comprising a mechanism for manoeuvring the brake between two positions, a first position enabling the free rotation of the drum and a second position in which the brake opposes the rotation of the drum up to the variable torque, wherein the brake manoeuvring mechanism is configured to deactivate the adjusting mechanism in the first position of the brake.
5. The winch as claimed in claim 4 , wherein the brake manoeuvring mechanism comprises a third plate disposed between the first elastic element and the first plate, the third plate being movable in translation along the axis of the drum, and wherein the brake manoeuvring mechanism is configured to compress the first elastic element by moving it away from the first plate in its first position and to leave the third plate free in its second position.
6. The winch as claimed in claim 5 , wherein the brake manoeuvring mechanism comprises a second elastic element disposed between the first plate and the third plate.
7. The winch as claimed in claim 1 , comprising a mechanism for manoeuvring the brake between two positions, a first position enabling the free rotation of the drum and a second position in which the brake opposes the rotation of the drum up to the variable torque.
8. The winch as claimed in claim 7 , comprising a motor for making the drum rotate, and a control module permitting the rotation of the motor in the first position of the brake manoeuvring mechanism and preventing the rotation of the motor in the second position of the brake manoeuvring mechanism.