Torque limit drive transmission

Roller friction gearing comprising a driving shaft, a driven shaft, the center lines of said shafts being parallel but offset radially of one another, an external annular roller-engaging surface secured to one of said shafts, means secured to the other of said shafts and having an internal annular roller-engaging surface, the spacing between said surfaces varying due to the offset of the center lines of said shafts and providing a narrowing pocket between said surfaces in the direction of rotation of the driving shaft, a plurality of rollers between said surfaces and acting to transmit torque from said driving shafts to said driven shaft, one of said rollers being a wedging roller mounted in said pocket and capable of moving further into said pocket as torque transmitted between said shafts causes relative deformation thereof, and positive means for limiting movement of said one roller into said pocket to induce slip between said rollers and said surfaces to limit the torque that can be transmitted from said driving shaft to said driven shaft, means initially biasing said one roller into said pocket, said one roller having an axial bore, a shaft loosely receiving said bore, and resilient biasing means acting between said shaft and said bore initially to bias said one roller into said pocket, said shaft having a cross-bore and a crosspin therein, and resilient means bearing on said crosspin to cause said crosspin to engage said crossbore resiliently to bias said one roller initially into said pocket.

Roller friction gearing comprising a fixed housing having two end portions, a driving shaft jornalled in one of said end portions, a driven shaft journalled in the other of said end portions, the center lines of said shafts being parallel but offset radially of one another, an external annular roller-engaging surface connected to one of said shafts and having an internal annular roller-engaging surface, the spacing between said surface varying due to the offset of the center lines of said shafts and providing a narrowing pocket between said surfaces in the direction of rotation of the driving shaft, and a plurality of rollers on axles mounted from one of said end portions and engaging said surfaces, at least one of said rollers being a wedging roller of predetermined internal diameter and fitting loosely about its axle for radial movement relative thereto, said last mentioned axle having a predetermined outside diameter only slightly less than said predetermined inside diameter, said one roller being received in said pocket, the difference between said outside diameter and said inside diameter being predetermined such that the axle of said roller limits movement of said roller into said pocket by a distance substantially equal to the predetermined difference between said diameters and applying a drag thereon whereby to induce slip between said rollers and said surfaces to limit the torque that can be transmitted from said driving shaft to said driven shaft.