History of gerotor hydraulics

The second part in a retrospective of the development of gerotor technology, the engineers behind the breakthroughs, and an acquisition here and there.

The design and manufacture of a line of high-speed gerotor motors was the result of the formation of Hydraulic Products, Inc. (HPI), which was cofounded in 1966 by John Pippenger and Don Dorff in Sturevant, WI, as a wholly owned subsidiary of Racine Hydraulics (Figure 1). The motors were used in applications such as traction drives, primarily for construction equipment.

Rotor sets were also produced for orbit motors manufactured by Char-Lynn. W. H. Nichols acquired HPI in 1969, the first corporate acquisition by Nichols. The high-speed gerotor motor line was transferred to the Hydraulic Pump and Motor Division of Parker Hannifin after W. H. Nichols was acquired by Parker in 1984.