Abstract: Apparatus for electronically dividing the primary step of a stepping motor to provide an increased number of steps per revolution of the motor. Integrated circuit counters operate in an incremental or decremental mode to sequentially access data words in a sine memory and a cosine memory. Digital-to-analog converters apply the digital data words of the sine and cosine memories to operate phase power transitors and to thereby generate corresponding amplitude changes in the controlled driving current of two associated active phase windings of the stepping motor. An incrementally increasing controlled current signal is applied to one activated phase winding and a corresponding incrementally decreasing controlled current signal is applied to the other of the activated phase windings to smoothly step the motor in angular increments corresponding to the increasing or decreasing amplitudes of current, as defined by the data words of the sine and cosine memories.

Abstract: A driven load is advanced to a selected position by the rotor of a large angle step motor, the housing of which is driven by a small angle step motor having a stationary housing. Driving pulses are fed to the plural phase windings associated with the large angle step motor under control of digital logic, by means of a slip ring assembly. Driving pulses are also fed to the plural phase windings of the small angle step motor under control of the same digital logic.

Abstract: Two step motors are interconnected so that the rotor or output shaft of one drives the stator or field structure of the other via a reduction drive assembly, so that the output shaft of the other motor may advance a load to an interpolated position between steps of the output shaft to which the load is directly connected. Anti-backlash means is associated with the reduction drive assembly which has a high reduction gear ratio to enable use of two motors both of which have large angle stepping angles.

Abstract: The drive ratio of a bicycle transmission is automatically varied through a radially contractible drive chain sprocket wheel assembly that is drivingly coupled to a pedal driven, drive ratio control disk. A force transmitting spring couples the control disk to the sprocket wheel assembly. A fluid-dash-pot device dampens angular oscillation of the control disk relative to the wheel assembly and reduces cyclic fluctuations in the drive ratio.

Abstract: A hybrid step motor system, in which a first step motor which steps A degrees per step and is provided with a load output shaft, has its stator driven by a second step motor which steps A/10.degree. per step, so that the system has a resolution of A/10.degree., when the motors are cascaded, but attains a given angular setting substantially in the time required by the first step motor to attain that setting.

Abstract: A digital step motor having a wobble plate which rotates about a shaft, to produce mating contact between two sets of associated gear teeth, under the influence of a stepping electromagnetic drive. The wobble plate is coupled to the shaft about which it rotates by a universal joint free to move axially but restrained radially of the shaft.