초록 ▼

A safety coupling for preventing backspin at excessive speeds of a torque transmitting drive string which stores reactive torque due to torsional stress. The safety coupling includes a rotatable driving member to be coupled with a rotatable driven member to be coupled with the driving string for axi

A safety coupling for preventing backspin at excessive speeds of a torque transmitting drive string which stores reactive torque due to torsional stress. The safety coupling includes a rotatable driving member to be coupled with a rotatable driven member to be coupled with the driving string for axial rotation therewith. The driven member is movable relative to the driving member between an engaged position wherein the driving and driven members are coupled by a torque transfer structure to provide a positive driving connection between the torque transmitting drive and the shaft, and a disengaged position wherein the driving and the driven members are freely rotatable relative to each other so that back-spin of the torque transmitting drive is prevented. The driven member is biased into the disengaged position and forced into the engaged position only during forward rotation of the shaft. To start rotation of the shaft, the coupling further includes an auxiliary coupling component which transfers a selected torque between the driving and driven members for start-up of the shaft from standstill and to force the driven member into the engaged position. The auxiliary coupling component is disengaged before potentially dangerous levels of reactive torsion are stored in the shaft, which prevents potentially hazardous back-spin, should the main coupling components of the driving and driven members and torque transfer structure fail.

대표청구항 ▼

[ I claim:] [1.] A safety coupling for releasibly connecting a torque transmitting drive to a drive string which stores reactive torque due to elastic torsion of the shaft, the drive string normally being rotated in a forward direction by the torque transmitting drive, and backspin of the drive stri

[ I claim:] [1.] A safety coupling for releasibly connecting a torque transmitting drive to a drive string which stores reactive torque due to elastic torsion of the shaft, the drive string normally being rotated in a forward direction by the torque transmitting drive, and backspin of the drive string being caused by the release, upon interruption of power to the torque transmitting drive, of the reactive torque stored in the drive string, the safety coupling comprising:a rotatable driving member to be coupled with the torque transmitting drive;a driven member to be coupled with the drive string for rotation therewith; the driven member being axially slidable relative to the driving member between an engaged position, wherein the driven member is coupled to the driving member, and a disengaged position, wherein the driven member is freely rotatable relative to the driving member;torque transfer means for releasibly connecting the driven member to the driving member in torque transmitting relation with each other when the driven member is in the engaged position;biasing means for forcing the driven member into the disengaged position at a preselected biasing force;clutch actuating means for forcing the driven member into the engaged position against the biasing force of the biasing means, the actuating means being automatically deactivated when rotation of the shaft stops or upon back-spin of the shaft and automatically activated only upon forward rotation of the shaft; andauxiliary coupling means for transmitting a selected amount of torque from the driving member to the driven member when the shaft is at standstill and the driven member is in the disengaged position, the selected torque being sufficient to initiate forward rotation of the shaft from standstill and activation of the clutch actuating means, but smaller than a torque required to build-up the elastic torsion in the shaft required to create a potentially hazardous back-spin of the shaft;whereby the driven member is allowed to freely rotate relative to the driving member during back-spin of the shaft to prevent back-spin of the torque transmitting drive during operation of the safety coupling.