Advertisement
(3)
Forces acting on the gear
The gear, whose outer surface is
subjected to oil pressure, receives forces
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
at right.
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, an 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 in a
shortened service life of the bearing or
interference of the gear with the case.
Suction
side
4-11
Drive gear
Discharge
side
Driven gear
Pressure distribution
(770-3ATM) 4-11
Advertisement
