The RBK’s drive function divides the basic 1.8∞ step angle up to 128 microsteps (0.018∞ step angle) in 16 selectable resolutions using built-in switches located on the driver. The third harmonic suppression reduces step motor torque vibrations by correcting or shaping the driver current waveforms. The RBK bipolar driver employs a constant current drive strategy over a wide voltage range of 20-75VDC. The effective current reaches 6.3 amps peak (4.5 amps RMS) per phase. There are two step motor frame sizes, with three models each. The smaller models are 2.22-inches in diameter (size 23) with holding torques ranging from 68 up to 240 oz-in. The larger 3.35” (size 34) in diameter models develop holding torques ranging from 310 to 910 oz-in. The second RBK series, the IP65 rated motor package, is composed of the same two frame sizes and three models each with similar holding torquesOriental Motor USA Corp.