Abstract: A monitoring system for a vehicle's air-brakes in which the push-rod extending from the brake chamber engages an electrical switch. The electrical switch, if moved to a pre-selected position (indicating that adjustment of the push-rod's connection to the brake is warranted) transmits electrical energy or other such signal to an alarm within the cab of the vehicle where either an auditory alarm is sounded or a warning lamp is illuminated. The monitoring system is operationally checked through the use of several alternative mechanisms. In one such check mechanism, a switch located near the warning lamp, allows the operator to transmit electrical energy to the remote switch located at the push-rod where the electrical energy is transmitted back to the warning lamp. In another check mechanism, a switch located near the warning lamp is used to engage a solenoid which pushes the remote switch into a transmitting position to check the entire monitoring system.