BC Transit – Air Brake Course

The Governor
The governor may be considered to be the brain of the air brake
system. It tells the compressor when to load and unload based on
the amount of air pressure in the reservoirs. Two standard main
reservoir operating pressures are:
•85 psi. to 105 psi. and 115 psi to 135 psi.
•Some systems operate at 85 psi. to 135 psi.
•The spread between loading and unloading pressures must
not be less than 20 psi.
•During the pre-trip inspection, the cut-in (load) and cut-out
(unload) pressures of the governor are checked.
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