Komatsu Galeo PC138US-8 Shop Manual page 111

10 Structure, function and maintenance standard
Function
The pump converts the engine rotation and
q
torque transmitted to its shaft to oil pressure
and delivers pressurized oil corresponding to
the load.
It is possible to change the delivery by chang-
q
ing the swash plate angle.
Structure
Cylinder block (7) is supported to shaft (1) by
q
spline (10).
Shaft (1) is supported by front and rear bear-
q
ings (11).
Tip of piston (6) is shaped as a concave ball
q
and shoe (5) is caulked to it to form one unit.
Piston (6) and shoe (5) constitute the spherical
q
bearing.
Rocker cam (4) has flat surface (A), and shoe
q
(5) is always pressed against this surface while
sliding in a circular movement.
PC138US, USLC-8
Rocker cam (4) conducts high pressure oil to
q
the cylinder surface (B) with cradle (2), which
is secured to the case, and forms a static pres-
sure bearing when it slides.
Piston (6) carries out relative movement in the
q
axial direction inside each cylinder chamber of
cylinder block (7).
Cylinder block (7) seals the pressurized oil to
q
valve plate (8) and carries out relative rotation.
This surface is designed so that the oil pres-
q
sure balance is maintained at a suitable level.
The oil inside the respective cylinder chambers
q
of cylinder block (7) is suctioned and dis-
charged through valve plate (8).
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