What information does a supply pressure gauge provide?

A supply pressure gauge is specifically designed to monitor the amount of pressure in the air tanks of a commercial vehicle. This gauge is crucial for the proper functioning of the vehicle's braking system and other pneumatic systems. A healthy pressure reading indicates that the air system is functioning correctly, which is essential for safe vehicle operation.

The gauge reflects the air pressure typically measured in psi (pounds per square inch), and it's important for drivers to regularly check this gauge to ensure that the air brake system has adequate pressure. Insufficient pressure can lead to brake failure, compromising safety on the road.

The other options provided do not relate to what a supply pressure gauge specifically measures. Fuel levels, vehicle speed, and engine temperature are monitored by different gauges and instruments, each designed for their specific purpose. Understanding the role of a supply pressure gauge is vital for maintaining effective vehicle control and ensuring safe operation.