Brake mechanism

A braking mechanism which becomes automatically effective when there is a reversal in the direction of applied torque, including:

• two members turned by the applied torque about a common axis and providing at least one braking surface engageable with a complementary braking surface of a surrounding housing;
• the two members being angularly displaceable and relatively axially moveable with respect to one another and having camming means arcuate about their common axis and engaged by thrust-resistant means which allow relative rotation of the members to bring different parts of the camming means into engagement with the thrust-resistant means and so vary the spacing between the members;
• the profile of the camming means being so chosen that relative rotation of one of the members in one direction of rotation with respect to the other, and produced by a reversal in the applied torque, causes the spacing between the members to change and bring said one braking surface into braking engagement with the complementary braking surface of the housing, and the mechanism also including a hydraulic pump operated by drive from one of the members and hydraulic ducts leading from the output side of the pump to the vicinity of the complementary braking surfaces to create a hydraulic cushion between them when the direction of torque through the mechanism is not reversed, the drive to the hydraulic pump diminishing, during braking, to collapse the cushion and permit prompt braking of the mechanism.

A braking mechanism which becomes automatically effective when there is a reversal in the direction of applied torque, comprising:

• a housing;
• first and second members in the housing and having a common axis of rotation and both being turned by the applied torque in a driving direction to rotate about said common axis, said first member being connected to be driven in unison with said applied torque in the driving direction and said second member being angularly displaceable and relatively axially moveable with respect to said first member and rotating in synchronism with it as long as the applied torque is in the driving direction;
• first and second braking surfaces on said first and second members respectively, said first and second braking surfaces being engageable with respective opposed braking surfaces of said housing;
• camming means arranged arcuately about the common axis of rotation of the first and second members and engaged by thrust-resistant means which is responsive to a reversal in the direction of the applied torque to bring different parts of the camming means into engagement with the thrust-resistant means to move the two members axially relative to one another to bring said first and second braking surfaces into braking engagement with their respective opposed braking surfaces of the housing to bring both members rapidly to rest;
• and
• means for manually applying torque to said second member to rotate the second member in the direction of the load with respect to said first member when both members have been braked to a halt, to allow the load to be progressively moved under complete control and in the direction of the reversed torque.