Service Manual 73
Page 3 of 32
General Description
The GG Series pumps use the internal gear design pumping principle (see Figure 1) to perform
the positive-displacement pumping action desired. Thus, the pump has only two moving parts,
the rotor and idler gear.
Figure 1 – Internal Gear Pumping Principle
Pumping action is based on a rotor, idler gear and crescent-shaped partition cast integral with the
cover.
Power applied to the rotor is transmitted to the idler gear with which it meshes. The space
between the outside diameter of the idler and the inside diameter of the rotor is sealed by the
crescent.
As the pump starts, the teeth come out of mesh, increasing the volume. This creates a partial
vacuum, drawing the liquid into the pump through the suction port.
The liquid fills the spaces between the teeth of the idler and the rotor and is carried past the
crescent partition through the pressure side of the pump.
When the teeth mesh on the pressure side, the liquid is forced from the spaces and out through
the discharge port.
The materials furnished for each pump are selected to suit individual applications.
Modular Design
The GG Series of pumps have a Modular Design concept. This allows for simplified maintenance
of the pump and a broad range of flexibility on the design. For more information, consult the GG
Series Catalog
or your authorized Tuthill distributor.
The GG Series of pumps allows for simplified repairs.
Back-Pullout—This allows the Drive Module ( rotor/bracket/bearing carrier/bearing caps
assembly) to be removed from the pump housing without disturbing the piping attachments. This
requires the use of a spacer coupling.
