What is a Gerotor  

The gerotor is a positive displacement pump mechanism, which will deliver a known, predetermined quantity of fluid in proportion to speed. Designers of engines, compressors, machine tools, tractors and other equipment requiring hydraulic systems can now build pump components integrally into these mechanisms... at a fraction of the cost of complete, separately purchased pumps. The designer will welcome the advantage of stacking compact gerotor elements along a single shaft to perform multiple pump functions -- lube, scavenge, boost, etc.

A three-piece "insert-package" makes this economical pump integration possible. Consisting of an inner and outer gerotor and an eccentric locator-ring, the unit becomes a complete pump simply by boring the casting or frame of the mechanism to accommodate the locator-ring O.D. and by providing porting. This design makes the main casting do double duty as the pump housing thus eliminating a very considerable cost factor. The gerotor drive can be taken from any convenient shaft. The designer has a choice of gerotors of various diameters combined with various lengths to provide the same capacity with maximum flexibility of envelope dimensions.

The resulting pump is a self-priming, positive displacement, lightweight, valveless mechanism. It is longwearing and handles impurities well. It can be made to pump in the same direction regardless of direction of rotation. It provides a relatively pulseless flow; volumetric and mechanical efficiencies are high; it is balanced and quiet in operation.

The gradual volume change of the gerotor tooth chambers across suction and discharge ports, each tapered to full open through nearly 180° of each pump revolution provides smooth uniform flow with a minimum of pressure variation, and eliminates the sudden shock and excessive turbulence which, particularly at high altitude, engenders foaming and lowered efficiency.

Gerotor elements revolve in the same direction with low relative speed since the inner gerotor advances only one tooth space per revolution. For example, in the 8030 gerotor running at 1800 RPM, the inner and outer gerotor revolve at only 200 RPM with respect to each other. Despite high shaft speed, tooth wear is obviously minimal. A single shaft with a single pair of bearings reduces shaft bearing maintenance problems to a minimum.

The continuous contact of each inner tooth with the outer tooth and the uniform clearances maintained by close manufacturing tolerances result in a fluid tight engagement of the two elements, providing high suction with high volumetric efficiency.

A wide variety of sizes are available covering capacities up to 100 GPM and 1,000 PSI.