At what psi does the governor tell the compressor to cut out?

The governor is a critical component of the air brake system in a School Pupil Activity Bus (SPAB), and it is responsible for managing the air pressure in the system. The correct answer indicates that the governor will instruct the compressor to cut out when the air pressure reaches 130 psi.

This pressure setting is essential because it ensures that the air brake system maintains adequate pressure for safe operation while preventing over-pressurization that could lead to system failures or damage. Compressors that run too long can lead to heat buildup and excessive wear, which is why the cut-out pressure is set at this specific level. The specified cut-out pressure is in accordance with industry standards and is designed to provide effective and safe operation of the bus’s air brake system.

In understanding why the other options are not correct, it is important to note that while 120 psi, 125 psi, and 135 psi are common values for various types of systems or for different configurations, they are not the operational standard for the SPAB governor in relation to compressor cut-out pressure.