The governor (Fig. 20), which is usually compressor mounted, operates in conjunction with the compressor and maintains reservoir air pressure between a predetermined maximum and minimum pressure.
- cut-out pressure 120 to 145 psi (828 to 1,000 kPa) maximum
- cut-in pressure 100 psi (690 kPa) minimum
The governor will normally cut in 20-25 psi below the cut-out pressure.

Figure 20. Air governor