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(3)
Forces acting on the gear
The gear, whose outer surface is subjected to oil
pressure, receives force jointing towards its
center. Due to the action of the delivery
pressure, the oil pressure in higher on the
delivery side of the pump, and due to suction
pressure, is lower on the suction side.
In the intermediate section, the pressure will
gradually lower as the position moves from the
delivery side to the suction side. This
phenomenon is shown in the drawing(refer to
right figure).
In addition, the gears in mesh will receive
interacting forces. These forces pushing the
gears toward the suction side are received by
the bearings. Since the gears are pressed
toward the suction side by these forces, the
radial clearance becomes smaller on the
suction side in the case. In some pumps, the
clearance may become zero, thus allowing the
gear teeth and the case to come into light
contact.
For this reason, and excessive increase in the
delivery pressure must be avoided, since it will
produce a large force which will act on the gears,
placing an overload on the bearings, and
resulting on a shortened service life of the
bearing or interference of the gear with the case.
Suction
side
Driven gear
6-14
Drive gear
Discharge
side
Pressure
distribution
100D7PMP28
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