Apparatus to assist doffing packages in a yarn windup

In a yarn winding apparatus that includes a frame, a pair of windup chucks cantilevered from opposite ends of an arm attached to a plate rotatably supported from the frame by a shaft, a drive roll positioned to contact yarn on one package support on one of the chucks in a winding position while the other chuck carrying another support is in a doffing position, said arm being attached to said plate in a fixed relationship during winding and being pivotally attached to said plate for relative rotary movement thereto during doffing, the improvement comprising:

• a collar rotatable on said shaft, said collar having a portion of its periphery cut out to provide an open section over part of its circumference, said open section being defined by two radial faces, a pin extending radially outward from said shaft into said open section;
• a constant force extension spring connected at one end to the periphery of said collar and at its other end to said frame, said spring leading partially around the periphery of said collar to said frame for applying a constant torque in one direction to said collar whereby said pin engages one of said two radial faces and means located near said one of said two radial faces to limit rotation of said collar with respect to said frame in said one direction whereby said shaft is free from the influence of said spring to rotate in said one direction until said pin contacts the other of said two radial faces.