Atlas Copco CR Series, Instruction Book, Page: 44 / 53

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Instruction book
Adjustment
• Adjust the air pressure switch while it is pressurized.
• Switch off the voltage before removing the cover of the switch; reinstall it after an
adjustment has been made and before the voltage is switched on again.
The stopping pressure is controlled by adjusting screw (2). Turn the screw clockwise to raise the stopping
pressure, counter-clockwise to lower it.
The pressure difference between starting and stopping is adjusted by means of adjusting screw (3). The
adjustment range is shown in the graph below. Turn the screw counter-clockwise to reduce the pressure
difference, clockwise to increase it.
6.4 Adjustment of pilot valve
The adjustment of the maximum or unloading pressure of the compressor is effected by means of pilot valve.
The valve also controls the difference between the preset maximum pressure and that at which compression is
resumed.
Pilot valve
Reference Description
A Control air to unloader
R Vent hole
1 Unloading handle
2 Pressure adjusting screw
3 Nuts
4 Shims