Abstract: The shaft which drives the tying needles of a baler back and forth across the bale chamber has a cam-operated brake associated therewith for intermittent application and release of the brake at preselected points along the path of swinging travel of the needles. The cam is located at the peripheral edge of a rotary member of the brake, and a follower is rocked by the cam to, in turn, shift a non-rotating brake member away from the rotary member to thereby release the brake. A series of coil springs yieldably bias the two members into cooperating frictional interengagement to apply the brake.