External gear pumps
BOMAG
77
008 921 86
7.7
7.7
External gear pumps
External gear pumps
External gear pumps mainly consist of the friction bearing mounted gear pair and the housing with front and rear
covers. The drive shaft, which is sealed with a radial seal, protrudes from the front cover. The bearing forces are
absorbed by friction bearings. These have been designed for high pressures and have excellent antifriction prop-
erties - particularly at low speeds. The gears have 12 teeth each. This keeps flow pulses and noise emissions
at a low level.
Fig. 9 Axial compensation of gear pump
Internal sealing of the pressure chambers is achieved by flow volume dependent forces. This results in an ex-
cellent rate of efficiency. On the rear side the moveable bearing bushings are pressurized and thus tightly
pressed against the gears. The pressurized pressure fields are thereby limited by special seals. Sealing around
the circumference of the gears to the housing is assured by small gaps, which appears between gears and hous-
ing in dependence on the pressure.
Function
Fig. 10
The increasing volume caused by a tooth exiting a tooth gap results in a vacuum in the suction chamber. The
pressure fluid is transported into the pressure chamber. There the meshing of teeth and tooth gaps displaces
the pressure fluid into the upper supply line.
Sealing zone
Compensation forces
Flange
Cover
Axial seal
Outer pressure field
Inner pressure field
Radial seal
Go
to
Discount-Equipment.com
to
order
your
parts
