Komatsu F30791, Shop Manual

Page: 46 / 298

OPERATION
1. Pump operation
1 - The cylinder block (7) rotates together with the
shaft (1), and the shoe (5) slides on the flat sur-
face A .
At this time, the rocker cam (4) moves along
the cylindrical surface B , so the angle
a
be-
tween the center line X of the rocker cam (4)
and the inclination of the cylinder block (7) in
the axial direction changes.
This angle
a
is called the swash plate angle.
2 - When the center line X of the rocker cam (4)
maintains the swash plate angle
a
in relation
to the axial direction of the cylinder block (7),
the flat surface A acts as a cam for the shoe
(5).
Bythis, the piston (6) slides on the inside of
the cylinder block (7), creates a difference be-
tween capacities E and F , then suction and
discharge of oil for the amount of this differ-
ence ( F ± E ) will be carried out.
In other words, oil is discharge as the capacity
of the chamber F decreases when the cylinder
block (7) rotates.
In the mean time, the capacityof the chamber
E increases, and the oil is sucked at this pro-
cess.
(The figure shows the state of the pump when
suction of the chamber F and discharge of the
chamber E have completed).
3 - When the center line X of the rocker cam (4)
becomes in line with the axial direction of the
cylinder block (7) (swash plate angle = 0),
the difference between capacities of E and F
inside the cylinder block (7) becomes 0, so
the pump does not carryout anysuction or dis-
charge action of oil.
(In actual fact, the swash plate angle never be-
comes 0).
4 - In other words, discharge amount of the pump
is directlyproportional to the swash plate an-
gle
a
.
10-28
PC20R-8 PC27R-8
RKP01240
4
5
7 1
B
X
E
F
A
6
RKP01260
F
7
4
E
X
= 0