Komatsu PC20R-8 Shop Manual page 45

FUNCTION
. The rotation and torque transmitted to the pump
shaft is converted to hydraulic energy and pressur-
ized oil is discharged according to the load.
. It is possible to change the discharge amount by
changing the swash plate angle.
STRUCTURE
. Cylinder block (7) is supported to shaft (1) by a
spline, and shaft (1) is supported by the front and
rear bearings.
. The end of piston (6) has a concave ball shape and
shoe (5) is caulked to it to form one unit.
Piston (6) and shoe (5) form a spherical bearing.
. Rocker cam (4) has plane A, and shoe (5) is always
pressed against this surface as it slides in a circle.
Rocker cam (4) forms a static bearing sending high
pressure oil at cylindrical surface B with to the
case, and carries out a sliding movement.
PC20R-8 PC27R-8
1 3 4
B
A
5
6
a
Section A - A
Sezione A - A
. Piston (6) carries out motion relative to the axial di-
rection inside each cylinder chamber of cylinder
block (7).
. The cylinder block (7) carries out rotation relative to
valve plate (8) while sealing the pressurized oil, and
this surface ensures that the hydraulic balance is
maintained correctly.
The oil inside each cylinder chamber of cylinder
block (7) is sucked in and discharged through valve
plate (8).
7
8
RKP01220
10-27