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
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.