DEUTZ-FAHR AGROTRON 106 MK3, Workshop Manual

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10-72
a. When the directional control valve is in «NEUTRAL» position
•
The pressure PLS of the LS signal from the control valve outlet port, enters the chamber a of the LS valve; the pump
delivery pressure PP enters the chamber b on the opposite side.
•
The shift in the position of the spool (1) is determined by the combination of the force exerted by the pressure PLS plus
the force of the spring (2) and the force exerted on the opposite side of the spool by the pressure PP .
•
Before the engine is started, the control piston (6) is pushed to the right by the spring (5) (position corresponding to
the maximum swash plate angle).
•
When the engine is started, if all the control valve spools are in «NEUTRAL» position, the pressure PLS of the LS
signal remains at 0 bar (0 psi) because there is no flow through the control valves and the signal is connected to drain.
At the same time, the pump delivery pressure
PP increases because the hydraulic actuators are stationary.
When the force exerted by the pressure PP in chamber b overcomes the force of the spring (2), the spool (1) shifts to
the right thereby allowing the pressure PP to flow to the chamber X of the piston (6) as the connection is made
between the passages c and d .
•
The force exerted by the oil pressure on the piston (6) overcomes the force exerted by the spring (5). This causes the
piston to shift to the left i.e. in the direction of the minimum swash plate angle.
•
The pump delivery pressure PP stabilises around 22 bar (319 psi), which corresponds to the standby pressure.
M
Min Max
D0004850
8
7
6 5
2 1
PLS
T
PEN
PP
X
b
PP
a
c
d e
HYDRAULIC SYSTEM LOAD SENSING VALVE, PRESSURE CUT-OFF VALVE