Komatsu Utility SK714-5, Shop Manual

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10-22 SK714-5 SK815-5 SK815-5 turbo
OPERATION
1. Operation of pump
• Cylinder block (9) rotates together with shaft (1),
and shoe (7) slides on flat surface
A .
When this happens, rocker cam (4) moves along
cylindrical surface
B , so angle
α
between center line
X of rocker cam (4) and the axial direction of cylinder
block (9) changes. (Angle
α
is called the swash pla-
te angle).
i) Center line X of rocker cam (4) maintains
swash plate angle
α
in relation to the axial di-
rection of cylinder block (9), and flat surface A
moves as a cam in relation to shoe (7).
In this way, piston (8) slides on the inside of
cylinder block (9), so a difference between vo-
lumes
E and F is created inside cylinder block
(9). The suction and discharge is carried out by
this difference
F - E .
In other words, when cylinder block (9) rotates
and the volume of chamber
F becomes smaller,
the oil is discharged during that stroke. On the
other hand, the volume of chamber
E becomes
larger, and as the volume becomes bigger, the
oil is sucked in (Fig. 1).
ii) If center line X of rocker cam (4) is in line with
the axial direction of cylinder block (9) (swash
plate angle = 0), the difference between volu-
mes
E’ and F’ inside cylinder block (9) beco-
mes 0, so the pump does not carry out any
suction or discharge of oil (Fig. 2).
iii) Center line X of rocker cam (4) maintains
swash plate angle
α
in relation to the axial di-
rection of cylinder block (9), and flat surface A
moves as a cam in relation to shoe (7).
In this way, piston (8) slides on the inside of
cylinder block (9), so a difference between vo-
lumes
E” and F” is created inside cylinder
block (9).
The suction and discharge is carried out by this
difference
E” - F” . In other words, when cylinder
block (9) rotates and the volume of chamber E”
becomes smaller, the oil is discharged during
that stroke. On the other hand, the volume of
chamber
F” becomes larger, and as the volu-
me becomes bigger, the oil is sucked in.
If the direction of swash plate angle is changed,
the relation between discharge and suction of
port PA, PB reverse (Fig. 3).
RKS00270
1
4 7 8
9 E
PA
PB
PA PB
α
X
A
F
B
Fig. 1
RKS00220
4
9
E'
PA PB
F'
0
Fig. 2
RKS00100
4 7
8 9
PA
PB
PA PB
α
X
F"
E"
Fig. 3
STRUCTURE AND FUNCTION
HYDRAULIC PUMP