Elements of a Successful Preventive Maintenance (PM) Program

Preventive maintenance (PM) is the key to any successful maintenance program for commercial motor vehicles. Through preventive maintenance, vehicles are inspected, repaired, and maintained in such a way that defects are prevented from surfacing in the first place, before a violation or accident can occur.

If vehicles are only brought into the shop when they need something, the program is not preventive, it is reactionary. The problem with reactionary maintenance programs is that they are based on failure, i.e., you notice something has failed and you fix it. This type of maintenance program is destined to lead to down-time and the resulting costs of idle equipment.

A preventive maintenance program, on the other hand, brings vehicles in for inspection and maintenance on a schedule, and repairs any items that are at, or even approaching, an established cut-off point. This allows you to make repairs on your schedule, prevent violations and accidents, and keep the vehicles rolling.

Preventive maintenance is also an attitude, a commitment. It means being constantly on the lookout for things that might go wrong. It means getting the best, most cost-effective equipment for the truck and then taking care of it. This is much like preventive medicine that stresses good eating habits and regular exercise as a continuing prescription for good health and long life.

The PM philosophy is widely used, not only because it reflects a modern attitude of conservation — of using assets wisely — but because it saves money. No one can argue with the bottom line. As PM takes hold, the standard of excellence for a maintenance shop changes from getting the fastest repairs to getting the fewest repairs.

Note that the federal regulations require a “systematic” inspection, repair, and maintenance program, but they leave the details up to you.

PM Schedules

The actual maintenance portion of PM is composed of scheduled and standardized inspections and maintenance. This is sometimes referred to as the vehicles’ “scheduled service,” or simply “service.” PM services are commonly designated as A, B, C, D, etc. As you move down the alphabet from A to B and so on, the PM service (and time required) increases in complexity.

PM A Service is also known as a “maintenance check-out” or “safety inspection” and generally consists of a safety check and lubrication as well as checks of key components such as brakes, lights, tire condition and inflation, and fluids. It also includes checking and adjusting high-wear components. The normal interval for “A” service is between 1,500 and 2,500 miles on light vehicles, and between 5,000 and 10,000 miles on medium- and heavy-duty vehicles.

Typically, these PM As are scheduled at half of the oil change interval of the vehicle.

Note: Some companies use an “inspection lane” and perform an “A” service every time the vehicle returns to the maintenance facility.

PM B Service normally includes all PM A items, as well as, an oil and filter change and more in-depth checks of the engine and driveline. The normal interval for “B” service is 3,000 to 5,000 for light-duty vehicles and 10,000 to 20,000 for medium- and heavyduty vehicles. A PM B should also include a download of the ECM and action on any trouble codes or problems reported by the ECM (if applicable).

PM C Service calls for both PM A and PM B service, as well as, more extensive service i.e. alignment, scheduled component replacement, DOT annual inspection, and other scheduled engine and driveline component inspection or replacement. Normally, “C” services are scheduled annually. To make sure they are done in a timely manner, it is not unusual for carriers to actually schedule them at an 11-month interval.

PM D Service is either a scheduled rebuild or replacement of a major component (e.g., engine, transmission, axle) or a “special” service. Examples of “special service” are seasonal service (winterization or summerization) and scheduled upgrade services. Scheduling of "D" services varies by company. The “D” designation may or may not be used, depending on the company.

Companies continue the lettering system based on their needs. Some companies go as far as PM L.

Trailer Inspections

It’s important to remember to establish a PM schedule for trailers as well as power units. Trailers should be subject to the same PM program as trucks. Typical preventive maintenance scheduling for a trailer is as follows.

T1 or TA Services are scheduled every 3 months. This PM service includes an inspection and lubrication, including a check of (at a minimum) the lights, tires, brakes, coupling devices, safety equipment, and any other “systems” (refrigeration unit, sliding axles, etc.).

T2 or TB Services are scheduled every six months. This PM service includes all the items of a T1 and a more in-depth inspection, as well as additional maintenance (pulling off hubcaps to check grease condition, retorquing lugs, etc.).

T3 or TC Services are normally scheduled annually. These include all the inspection and maintenance included in a T1 and T2 service, along with more extensive maintenance such as an alignment or complete brake overhaul. Some carriers will also perform the periodic (annual) inspection required under §396.17 as part of the Type T3 service.

Don't forget the auxiliaries! Auxiliary power units (APUs), refrigeration units, wet kits, hydraulic pony engines, and idle reduction equipment all need to undergo the same scheduling process as the vehicles and trailers. The maintenance scheduling for these units can be rolled into the vehicle they are associated with. Examples would be servicing the wet kit on a vehicle each time the vehicle is serviced and servicing an APU as part of an annual inspection

Inspection Lane

An inspection lane is a designated lane or shop bay where vehicles entering and/or exiting the facility must check in or out. When a vehicle enters the inspection lane, a technician will do an inspection. An inspection lane can be used to serve as a location to perform “A” inspections, if the truck is due for one, or it can be used strictly as a screening location.

In a “screening,” the technician can check items such as driver complaints, body damage, fluid leaks and levels, lights, wipers, springs, brakes, tire pressures, and time or mileage since the last PM. The truck might also be washed. If a problem is discovered, the technician can then communicate the problem to the maintenance supervisor. The vehicle can then be scheduled for repairs or service in the regular maintenance/repair area.

Also, if the vehicle is being checked into the yard, the driver can submit his or her DVIR to the technician doing the inspection, beginning the DVIR process while in the inspection lane.

The inspection lane can be located within the shop, but it is more often located in the yard next to the shop because it’s more convenient for the driver to drive through an open area rather than back into or drive into a building. Also, having space available in the yard is more predictable.

It should be noted that the inspection lane supplements the driver inspection and the regular PM inspections; it does not replace them.

Yard Checks

The inspection-lane routine may prove to be too expensive or cumbersome for every fleet. In place of it, some companies use a process of “yard checks.” At specified times throughout the day, technicians will “cruise the yard” and check the equipment that is newly arrived into the yard. These checks involve simple items such as brakes, tires, lights, body damage, and upcoming maintenance requirements. The technician will then record all units in the yard, and what work was done on which vehicles. If a vehicle is found to be in need of major repair or PM during the yard check, the technician will tag the unit as due for maintenance or repair, and then report it to the maintenance supervisor. The vehicle will then be worked into the shop for the needed work (similar to what happens in an inspection lane).

Other carriers do not use inspection lanes or yard checks at all, and rely entirely upon schedules and the drivers reporting to the shop when a vehicle is due for PM or in need of repair.

The bottom line is that only you can decide how much PM to give your vehicles, and how to schedule it.

Pre-Service Inspection

The concept of a pre-service inspection should be applied to all equipment new to the fleet, whether new or used.

With used trucks, beginning with a “C” level PM inspection (and service) is preferred and recommended. Additionally, all accessible nuts, bolts, and adjustments (lug nuts, hub nuts, axle nuts, bell housing bolts, motor mounts, dash screws, front-end alignment, etc.) not normally checked as part of a level C inspection should be checked, retorqued, and/or adjusted. Developing a pre-service checklist of what you consider key components is critical.

New trucks can benefit from this process as well. Since everything is new, you may be less concerned with the overall condition of the unit, but you will still want to make sure everything has been properly located and torqued. Also, you’ll want to be sure that everything you specified is on the line-setting sheet and actually on the vehicle. You will also want to check the model and serial numbers, sizes, etc. of all components, and log them into your recordkeeping system.

You should also consider doing pre-service inspections on vehicles that have been inactive for a significant amount of time (due to extended maintenance, driver unavailability, accident repairs, etc.).

Fleets that consider the pre-service check to be an important part of PM assign the mechanics who will be in charge of the vehicle to the task. Managers who feel a superficial check is good enough assign a less-expensive employee. Either way, it is probably to your advantage to use a detail-oriented employee.

You will have to create your pre-service standard according to the equipment. The line-setting sheet gives the frame of reference; you determine what checks will need to be made and develop the list from there. That checklist is, in a sense, the first service document of the new truck. As such, it becomes a standard quality control reference. On it you may want to include the quantities and grades of fluids added, belt tensions, tire pressures, etc.

Deciding how soon you wish to bring a new tractor back into the shop for a follow-up inspection after its pre-service inspection is your next decision. This may seem like an unnecessary procedure, but again, the idea is to catch things before they happen. The follow-up inspection is actually part of the shakedown, and the vehicle should not be considered as fully in service until this step is completed. This is because the maintenance department cannot simulate the operational environment the vehicle will be operating in no matter how hard they try. Allowing the vehicle to operate in the environment during a short shakedown period will allow any potential problems to be dealt with early.

Sometimes a representative from the dealership is present during different phases of the pre-service inspection process. This can be an advantage if something has to be changed by the manufacturer, especially if you want immediate action.

You might also use the pre-service inspection process to familiarize drivers with the new vehicle.

Trailers should be looked at carefully too. A new trailer should be put through the same paces. Too often a trailer is neglected, especially for the pre-service check, which may seem unimportant. Like tractors and trucks, federal regulations require that trailers have a regular maintenance schedule.

If you are going to add any special equipment to a vehicle during the pre-service period (lift gates, autogreaser, etc.) or at any other time, you will want to add a couple of steps to the process. First, verify that the alterations are legal by checking Part 393, Part 571, and Appendix G. Then be sure to add the work to your pre-service and inspection checklists.