GB871853A - Improvements in freewheel or unidirectional clutch devices - Google Patents

Abstract

871,853. Ratchet clutches. DAIMLERBENZ A.G. June 10, 1959 [June 10, 1958], No. 19894/59. Class 80 (2). A ratchet clutch comprises inner and outer races 2, 3, 4 with balls 1 therebetween mounted in a two-part cage 5, 6, the arrangement being such that in one direction of relative rotation between the races the balls wedge the two-part cage firmly against the races for torque transmission, while in the other direction of relative rotation, the balls run freely and the clutch acts as a ball bearing. The cage part 5 is formed with a frusto-conical surface 9 engaging frictionally with the surface of the outer race 3, and the cage part 6 is formed with a similar surface 10 engaging frictionally with the surface of the inner race 2. Springs (not shown) may be provided to bias the two parts of the cage away from each other in the axial direction and lightly against their coacting friction surfaces. The ball-receiving pockets in the cage consist of arcuate surfaces 7, joined by short rectilinear surfaces 8 inclined to a plane normal to the axis of the clutch. In the stationary condition shown, the balls 1 lie freely in the cage pockets. If it is assumed that the outer race 3, 4 remains stationary while the inner race 2 rotates in the direction of the arrow 11, Fig. 2, then on initiation of such rotation, the frictional engagement between the inner race and the cage part 6 draws the latter round so that the arcuate sections 7 of the pockets thereof engage the balls 1, and push them into the arcuate sections 7 in the pockets of the cage part 5, which latter tends to remain stationary because of its light frictional engagement with the outer race. Accordingly the balls 1 are located in the parts of the cage pockets having maximum axial width, and roll freely between the inner and outer races. If, however, with the outer race 3, 4 still held stationary the inner race 2 is rotated in the direction of the arrow 12, Fig. 2, then the rectilinear surfaces 8 of the cage part 6' engage the balls 1 as the cage part turns with the inner race. The balls 1 are thereby moved against the corresponding rectilinear surfaces 8 on the cage part 5, so that they cam the two cage parts axially away from each other and into firm engagement with the inner and outer races. Torque is accordingly transmitted between the inner and outer races 2, 3, 4. As shown, the outer race 3, 4 is in two parts, but alternatively it may be of unitary construction, while the inner race 2 may be of two-part construction.