DEUTZ-FAHR AGROTRON 106 MK3, Workshop Manual

Page: 86 / 150

10-68
OPERATION
1. Pump operation
1 - The cylinder block (4) rotates with the shaft (1)
and the piston shoes (6) slide on the flat surface
«
A ».
The swash plate (3) can swing within the arc « B »;
the stroke of the pistons varies according to the
angle «
α
» between the shaft axis (1) and the X
axis of the swash plate (3).
Angle «
α
» is known as the «swash plate angle».
2 - When the axis X of the swash plate (3) is at an
angle «
α
» to the shaft (1) and consequently to the
cylinder block (4), the surface « A » acts as a cam
for the piston shoes (6). Consequently, as the
shaft rotates, the pistons (5) stroke within their
bores in the cylinder block (4), thereby a creating
a difference between the volumes
C and D which
causes oil to be drawn in and forced out in
q u a n t i t i e s e q u a l t o t h i s d i f f e r e n c e (
D –
C =delivery).
In other terms, as the cylinder block (4) rotates,
the volume of chamber
D is reduced while the
volume of chamber C is increased, thereby
causing oil to be drawn in.
(Fig. 1 shows the condition of the pump on
completion of the suction stage in chamber
D
and the delivery stage in chamber C ).
3 - When the axis X of the swash plate (3) is parallel
to the axis of the cylinder block (4) (swash plate
angle «
α
»=0), the difference between the
volumes C and D inside the cylinder block (6) is
zero and no oil is pumped (Fig. 2).
(In reality, the swash plate angle «
α
» is never truly
equal to 0).
4 - The pump delivery is therefore directly
proportional to the swash plate angle «
α
».
2. Controlling the requirement of oil
•
At a given rotation speed input, the required oil
flow is controlled by the angle «
α
» between the
swash plate (3) and the shaft (1).
The swash plate (3) is inclined by the springs (10).
Against the spring works the control piston (8).
The position of the control piston (8) defines the
angle «
α
».
•
Below the max. pressure «
α
» is adjusted in this
way, that between the pressure of the pump and
the pressure of LS-signal is a certain difference
(control pressure difference).
•
Work the pump at the max. pressure, «
α
» is
adjusted to that position which guaranteed not
to exceed this pressure.
That means «
α
» is set to a smaller value than
from LS-signal whished. (Fig. 3).
D0000530
4
C
6
S A
3
1
x
␣
B D
D
4
C
3
x
Fig. 1
Fig. 2
D0005020
C
8
␣
D
3 2
10
Fig. 3
HYDRAULIC SYSTEM HYDRAULIC PUMP