Preventive maintenance (PM) is crucial to all trucking companies that want to be successful in managing their mechanical expenditure and well being of the drivers. What is PM? Loaded commercial vehicles can weigh 80k LBS and more. And commercial vehicle breaking down while on highway can be fatal for both the driver and people around. In preventative maintenance trucks are checked, fixed, in a way that breakdowns are prevented in the first place, before a accident or violation can happen. If trucks are checked and repaired when they need something,it is not considered preventive, it is called reactionary. Reactionary repair programs are based on failure. It is when a driver notices a problem in the truck and brings the truck to the shop. Reactionary program is destined to cause to down-time and costly repair of the fleet. Preventive maintenance program, on the other hand, keeps the truck rolling by maintaining scheduled repairs and prevent accidents and violations while the truck is at work. Preventive maintenance is being careful and watching out for things that might bread down. Preventative maintenance saves lives, saves money and reduces stressful moments for both the truck drivers and the managers. PM schedules PM services are mostly marked as A, B, C, D, etc. Moving down the alphabet shows how complex the check up should be. PM A service is a “maintenance check-up” or “safety inspection” includes safety check and lubrication, checks brakes, lights, tires thread and inflation, checking fluids, checking and adjusting high-wear components. Average interval for “A” service is between 5,000 and 10,000 miles on heavy-duty vehicles. PM A is scheduled at half of the oil change interval of the commercial vehicle. PM B includes all PM A check ups, as well as oil and filter change, engine and driveline check ups. Average interval for “B” service is 10,000 to 20,000 for heavyduty vehicles. A PM B includes action on any trouble codes or problems reported by ECM if there is any. PM C includes both PM A and PM B plus more extensive service for instance, alignment, scheduled part replacement, DOT yearly inspection,etc. Usually, “C” services are scheduled once a year. It is better to actually schedule them at an 11-month interval so you don't miss the annual schedule. PM D is for rebuilding or replacing major components such as axle, motor and transmission or some special major service. Scheduled upgrade, winterization or summerization can be examples for special service. Trailer inspections PM schedule for trailers are as important as for power units.Typical PM service for a trailer is as follows: T1 or TA. Done every 90 days. It includes inspection of the lights, brakes, coupling devices, tires, safety equipment in the truck, sliding axles etc. T2 or TB is scheduled every 180 days or 6 mnths. It includes T1 service as well as additional maintenance filling up hub grease, retorquing lugs, etc. T3 or TC is scheduled annually and includes everything in T1 and T2 plus more extensive maintenance such as an alignment or complete brake system repair. It is important to keep in mind auxiliaries. Auxiliary power units (APU), reefer units and other auxiliaries need to go through routinely check ups just like power units and trailers. Auxiliary maintenance can be included in truck or trailer PM service. Remember it is less costly and less stressful with PM service.