Application of Infrared Thermography on Bus Air Compressor Units for Preventive Fault Detection

The following paper presents the application of Non-destructive Testing methods such as thermography for fault finding in internal components of buses and specifically the air compressor unit. Such units consist of a small internal combustion engine that provides air to the vehicle’s breaks, suspension and passenger door operations. Hoses transferring compressed air from the compressor to the rest of the system can get clogged, leading the air compressor to potential failure and even fire of the unit. Thermal imaging was applied in a number of Mercedes Citaro LE and Volvo B9 buses provided by a bus fleet operator, to evaluate whether such clogging can be detected at an early stage, during routine maintenance of the bus. A number of acquisitions, using a thermal camera were taken, with the air compressor under different loads and under heating or cooling phase of the unit. The paper presents that thermography can be used to detect such failures by observing specific hoses of the unit as well as the overall thermal behaviour of the air compressor.