A. Spring 19 is adjusted to the maximum pressure desired in the main
reservoir usually 130 pounds.
18. Q. Explain the operation of the governor when the main reservoir
pressure exceeds the tension of the regulating spring 19.
A. When the pressure in chamber "a" exceeds the tension of the
regulating spring 19, the diaphragm 20 is forced upward, unseating the
pin valve, allowing air to flow from chamber "a" to chamber "b" above
the governor piston, forcing it down, shutting off steam and stopping
the compressor.