DEUTZ-FAHR AGROTRON 106 MK3, Workshop Manual

Page: 89 / 150

10-71
LOAD SENSING (LS) VALVE
FUNCTION
•
The LS valve regulates the pump delivery in accordance with the position of the control lever of the directional control
valve i.e. in accordance with the demand from the loads.
•
The LS valve senses the demand from the loads by way of the pressure difference
∆
PR between the pump delivery
pressure PP and the pressure at the outlet port of the directional control valve PLS ; this enables the valve to regulate
the delivery Q of the main pump.
( PP , PLS and
∆
PR , are respectively: the pump delivery pressure, the pressure of the Load Sensing signal and
difference between these two pressures).
•
In other terms, the LS valve detects the pressure difference
∆
PR , generated by the the flow of oil passing through the
passages uncovered by the spool and regulates the pump delivery Q so as to maintain a constant pressure drop.
This means that the pump delivery is proportional to the demand from the directional control valve.
OPERATION
Pump operation can be divided into four stages:
a. When the directional control valve is in neutral position
b. When a control lever is operated
c. When the flow rate stabilises
d. When the system enters “saturation” condition
HYDRAULIC SYSTEM LOAD SENSING VALVE, PRESSURE CUT-OFF VALVE