Nuttall's parallel shaft increaser units incorporate precision helical gearing (in single, double, triple, quadruple and quintuple reductions) enclosed in heavy duty cast iron or welded steel housings. Standard features include tapered roller bearings, large inspection plates, a positive splash system for lubrication, extra wide bearing spans and center bearing supports; all to provide a rugged, reliable unit with proven dependability. Can be assembled with a variety of horizontal input and output shaft arrangements extending on either side of the speed reducer.