Komatsu Galeo PC138US-8 Shop Manual page 112

SEN02548-01
Operation of pump
Cylinder block (7) rotates together with shaft
q
(1), and shoe (5) slides on flat surface (A).
When this happens, rocker cam (4) moves
q
along cylindrical surface (B), so angle (a)
between center line (X) of rocker cam (4) and
the ax ial di rec tio n of cy li nder b loc k (7)
changes.
(a) is named the swash plate angle.
q
With center line (X) of rocker cam (4) at a
q
swash plate angle (a) in relation to the axial
direction of cylinder block (7), flat surface (A)
acts as a cam in relation to shoe (5).
In this way, piston (6) slides on the inside of
q
cylinder block (7), so a difference between vol-
umes (E) and (F) is created inside cylinder
block (7).
A single piston (6) suctions and discharges the
q
oil by the amount (F) – (E).
As cylinder block (7) rotates and the volume of
q
chamber (E) becomes smaller, the pressurized
oil is discharged.
On the other hand, the volume of chamber (F)
q
grows larger and, in this process, the oil is suc-
tioned.
12
10 Structure, function and maintenance standard
As center line (X) of rocker cam (4) matches
q
the axial direction of cylinder block (7) (swash
plate angle (a) = 0), the difference between
volumes (E) and (F) inside cylinder block (7)
becomes 0.
Suction and discharge of pressurized oil is not
q
carried out in this state. Namely pumping
action is not performed. (Actually, however, the
swash plate angle is not set to 0)
PC138US, USLC-8