Monitoring
The compressed air brake system can be monitored via brake gauges, typically located in the cab of a motorized vehicle .
Main reservoir pressure should always be at, or near, 8 bar, and it is automatically refilled by the compressor .
Brake pipe operating pressures are between 3.5 bar when the brake is fully applied and 5 bar when it is fully released. Brake pipe pressure is usually represented by a black or white needle on the brake pipe gauge, and its pressure is controlled by the train brake control device.
Brake cylinder pressure goes between 0 and 3.75 bar and represents the actual braking force applied to the wheels . Brake cylinder pressure is usually represented by a red needle on the brake pipe gauge.
Since gauges display pressures relative to the atmospheric pressure, the actual absolute pressures are approximately 1 bar higher than what's indicated on the gauge and used in technical documentation.
For better brake cylinder reading visibility, there is a Brake Cylinder LED Bar gadget , which can be bought in one of the shops .