A trouble-free operation of any equipment is a top priority task. A lack of technical tools to monitor a wear of friction parts directly on operating devices without putting them out of operation and dismantling leads to a premature failure of the equipment. Given a sharp growth of overhaul costs, sometimes it isn’t advisable to repair damaged equipment. To timely detect and prevent emergency wear and of friction parts, reduce fuel, lubricant and spares consumption, and cut overhaul expenditures, built-in (aboard) diagnostic tools are recommended to be implemented.