What does an application pressure gauge indicate?

An application pressure gauge provides a direct measurement of the air pressure being applied to the brakes when the driver engages the brake pedal. This gauge is crucial for understanding how much braking force is being generated, as it indicates the level of pressure in the air brake system at any given moment during operation. A higher reading on the gauge indicates more air pressure is being directed to the brake chambers, which corresponds to a stronger braking action. This measurement helps drivers assess brake performance, as it indicates whether the brakes are functioning effectively and applying the necessary amount of pressure for safe stopping.

The other options do not correctly describe the role of the application pressure gauge. It does not measure the temperature of brake fluid, as air brake systems operate differently and do not use liquid brake fluid in the same way as hydraulic systems. It also does not provide an overall condition of the braking system without additional context, and it does not measure the specific strength of the parking brake.