ARAG Electriccontrol unit for crop-spraing application 871 - Manual (Page 18)

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5.1.1 Constant pressure units (Fig. 7a and 7b)
This kind of unit does not have a proportional valve, therefore the calibration of the operating pressure
is carried out by the maximum pressure valve.
The adjustment is made by turning the knob on the maximum pressure valve until operating pres-
sure is obtained:
• turn clockwise to increase pressure;
• turn anticlockwise to decrease pressure.
Fig. 7a Fig. 7b
5.1.2 Units with proportional valve (Fig. 8)
The calibration of the operating pressure is carried out by the proportional valve.
To adjust, operate the relevant switch on the control device until achieving the desired pressure.
Fig. 8
In this case, the proportional valve must be used for pressure
adjustment and not the maximum pressure valve since the propor-
tional valve would not compensate the variations in speed correctly
should the operating pressure be too close to the calibration of the
maximum pressure valve.