Sectional view(D12C)
This pump assembly consists of two pumps connected by spline coupling.
The suction and delivery ports are integrated at the connecting section of the two pumps: The common
suction port serves both the front and rear pumps.
The pump consists of rotary group, swash plate group and valve block group.
The rotary group consists of front drive shaft, cylinder block, piston and shoe, set plate, spherical bushing,
and cylinder spring. The drive shaft is supported by bearings. The shoe is caulked to the piston to form a
spherical coupling. It has a pocket to relieve thrust force generated by loading pressures and create a
hydraulic balance so that it slides lightly over shoe plate.
The sub group composed of a piston and a shoe is pressed against the shoe plate by the action of the
cylinder spring through the set plate and spherical bushing. Similarly, the cylinder block is pressed against
valve plate by the action of the cylinder spring.
The swash plate group consists of swash plate, shoe plate, swash plate support, tilting bushing, tilting pin
and servo piston.The servo piston moves to the right and the left as hydraulic oil controlled by the
regulator flows to a hydraulic chamber located on both sides of the servo piston. The force exerted on the
tilting pin by the servo piston causes the swash plate to slide on support to change the tilting angle.
The valve block group consists of valve block, valve plate and valve plate pin. The valve plate which has
two crescent ports is attached to the valve block to feed oil to and collect oil from the cylinder block. The
oil discharged via the valve plate is routed to an external pipe line by way of the valve block.
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