When inspecting the supply circuit, the governor cut-in pressure should be at least how much less than the cut-out pressure?

The governor cut-in pressure in the air brake system is the point at which the governor activates the compressor to build up air pressure in the system. It is essential that this cut-in pressure is set appropriately in relation to the cut-out pressure, which is when the governor stops the compressor from working.

The requirement that the cut-in pressure should be at least 20 psi less than the cut-out pressure ensures a sufficient margin for the compressor to operate efficiently. This difference prevents the system from cycling too frequently and ensures that there is enough air pressure available for braking and other functions. When the cut-in pressure is at least 20 psi lower than the cut-out pressure, it allows for an effective build-up of pressure to ensure the brakes perform optimally and minimizes the risk of compressor failure from rapid cycling.

In the context of air brake safety and functionality, maintaining this required differential is crucial for preventing operational issues and enhancing overall vehicle safety.