This invention relates generally to clutch mechanisms and more particularly, it relates to an improved clutch having oversized rollers.
In prior art clutches of the type utilizing rollers for achieving a clutching connection between a clutching member and a clutched member, the force-transmitting rollers are rolled "up" a ramp surface in channel means of the clutching member so as to create the clutching connection by pinching the force-transmitting rollers into engagement between the clutching member and the clutched member. For the purposes of completeness, reference is being made to my prior U.S. Pat. No. 3,557,631 which reissued as U.S. Pat. Re.No. 28122 and to my two co-pending U.S. applications, Ser. No. 506,538, now U.S. Pat. No. 3,930,416 and Ser. No. 506,594, now U.S. Pat. No. 3,951,005, wherein the clutches of the type having force-transmitting rollers for achieving a clutching connection is described and illustrated with application to a speed reducing mechanism.
In such prior art clutches, due to the weight of the driven shaft and the clutched member acting under the force of gravity on the lower force-transmitting rollers, difficulties have been encountered in providing a smooth and uniform movement of all of the force-transmitting rollers when they are urged in operation toward the narrow end of the channel means for engagement with the clutched member. In this particular situation, the upper force-transmitting rollers tend to move more readily into the narrow end of the channel means because of the action of gravity on the clutch members. On account of such gravitational forces and the fact that the upper rollers move more readily up the ramp, the lower rollers move into the narrow end of the channel means with greater difficulty and often not simultaneous with the upper rollers. This results in uneconomical and inefficient transfer of force or torque from the clutching member to the driven shaft. Further, when the force-transmitting rollers are returned to the larger end of the channel means (disengagement of the clutched member) additional difficulties have been encountered in providing an adequate friction free engagement between the clutching member and the clutched member again due to the weight of the clutched member.
Another problem exists in that the force-transmitting rollers become misaligned and askew to the axis of rotation of the driven shaft. This again results in an inefficient transfer of force. Additionally, in applications to a speed reducing mechanism (as in previously mentioned patents) having two arms each with a clutch associated therewith, the force-transmitting rollers are aligned serially and parallel to the axis of rotation of the driven shaft. In this case, a disadvantage occurs when the aligned force-transmitting rollers contact and rub against each other thereby making the force-transmitting rollers askew or cock-eyed and preventing a uniform and constant rate of rotation of the driven shaft or efficient transfer of forces between the clutching member and clutched member.