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4.8.3
Adjusting the nozzle flow rate
The nozzle flow rate varies according to the fuel pressure on the
nozzle return.
Diagram (Fig. 16) indicates this relationship for type A4 return flow
nozzles with pump delivery pressure of 290 PSI. See Fig. 16:
Horizontal axis:
PSI, nozzle return pressure
Vertical axis:
GPH, nozzle flow rate
The values indicated in the right side of the diagram (Fig. 16), refer
to the data printed on the nozzle.
With a pump delivery pressure of 290 PSI, the pressure on the noz-
zle return must not exceed 246.5 PSI.
The pressure difference between pump delivery and nozzle return
must be at least 43.5 PSI. With smaller pressure differences, the
pressure on the nozzle return can be unstable.
The nozzle return pressure value is indicated by the pressure
gauge 1)(Fig. 15).
The output and the pressure of the nozzle are at maximum when
the servomotor is positioned on maximum.
The proper setting of the eccentric 6) is possible when its operation
field follows the servomotor operation field (0° - 90°): so, that every
variation of the servomotor position corresponds to a pressure vari-
ation.
If at the maximum capacity of the nozzle (maximum pressure in the
return line) pressure fluctuations are detected on the gauge 1),
slightly decrease the pressure in the return line until they are com-
pletely eliminated.
Type A4 return flow nozzle (45°)
Delivery pressure 290 PSI
D2355
The values indicated in the right side of the diagram (Fig. 16), refer
to the data printed on the nozzle.
20031446
Installation
3
D10493
1
Gauge for pressure in return line
2
Gauge for pressure in delivery line
3
Low oil pressure switch
4
Ring for piston stop
5
Nut and lock-nut for piston setting
6
Fixed eccentric
7
High oil pressure switch
Return pressure - PSI
20
GB
2 1
7
4
5
6
Fig. 15
Fig. 16
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