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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. Under the normal system, every letter you move up into the alphabet represents an increase in the complexity of the PM service (and time required).
PM A services are also known as a “maintenance check-out” or “safety inspection” and generally consist 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. Typically, these PM As are scheduled at half of the oil change interval of the vehicle. 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.
Note: Some companies use an “inspection lane” and perform an A service every time the vehicle returns to the maintenance facility.
PM Bs normally include all PM A items, and also include an oil and filter change, as well as 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 heavy duty 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).
With the long oil change intervals seen in some applications using certain oils (such as large diesel engines using synthetic or semi-synthetic oils), a new concept is emerging called the “dry service” or the “dry PM B.” This involves doing all of the inspection and service items involved in a PM B at the previously established interval, except changing the oil. The engine oil and filters are only changed during a PM B when the vehicle has exceeded a specific number of miles or hours. A normal rotation is one dry PM B, then a wet PM B. The full sequence of PM As and PM Bs in a program using wet and dry PM Bs would be: PM A, dry PM B, PM A, wet PM B, PM A, dry PM B, and so on.
An additional consideration with passenger-carrying vehicles is that the pushout windows, emergency doors, and emergency door marking lights must be inspected once every 90 days. If the vehicles will not be undergoing PM Bs within 90 days, then this inspection item will need to be included in the PM A inspections for these vehicles.
PM C service calls for both A and B service items and a more extensive service (i.e., alignment, vehicle component replacement, scheduled engine and driveline component inspection or replacement, etc.). Many carriers will also do the DOT annual inspection required by §396.17 (see the Compliance Management and Regulations sections for more information on this required inspection). Normally, C services are scheduled at least annually, due to the annual inspection requirement in §396.17. To make sure they are done in a timely manner, it is not unusual for carriers to actually schedule them on an eleven-month schedule. Carriers based in California, where there is a 90-day inspection requirement in the state law, will normally schedule at least the inspection portion of the C services for every three months.
PM D service is either a scheduled rebuild or replacement of a major component (i.e. 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.
Don’t forget the trailers! Trailers are subject to the same regulations as the vehicles that pull them and should be subject to the same type of PM program. Typical preventive maintenance scheduling for a trailer is:
- 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 PMs 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.
Enforcement Note
Every year, FMCSA’s roadside inspection data shows the bulk of vehicle problems fall into three component areas: problems with lights, brakes, and tires. By the way, this coincides with the most common vehicle problems seen in maintenance inspections. Therefore, inspecting lights, brakes, and tires should be included in all maintenance activities.
Don't forget the auxiliaries! Auxiliary power units (APUs), refrigeration units, wet kits, hydraulic pony engines, lavatory systems (in motorcoaches), 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 or exiting (or both) the facility must check in or out. When in the inspection lane a technician will do an inspection on the vehicle. An inspection lane can be used to serve as a location to perform A inspections, if the vehicle is due for one, or it can be used strictly as a screening location.
In the “screening location” function 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 vehicle might also be washed quickly. 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 driver vehicle inspection report (DVIR) to the technician doing the inspection (if required). Drivers must submit a DVIR at the end of the workday if there is a defect on the vehicle. However, for a variety of reasons, many companies require their driver to submit daily DVIRs. The practice of having the driver complete his/her DVIR in the inspection lane at the end of the day allows the technician to immediately and officially determine if there are any driver-reported defects and triggers action on any needed repairs.
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.
Timing is the critical element for this kind of inspection. Usually a vehicle gets inspected every time it enters or exits the yard, so the inspection must be done quickly. Some fleets are very strict about this requirement; a vehicle has to run through the lane even though it may have been gone for only a half-hour. If the inspections take too long, it may be difficult to maintain operational support for the inspection lane.
Fleets who use inspection lanes often run time-critical movements, i.e. passengers or food service delivery, and management wants to be absolutely sure that vehicles are in top condition every time they are in the terminal.
Maintenance people who use inspection lanes emphasize that if you are considering adding this kind of inspection, you should resist the temptation to make even minor repairs in the lane. All repairs must be done in the shop and accompanied by the appropriate request paper work, repair order, etc. However, some regular servicing may be scheduled for the lane.
One fleet, for example, greases their trucks during every inspection lane visit. It should also be mentioned that the inspection lane supplements driver inspection and the regular PM inspections; it does not replace them.
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.
Best Practice
The bottom line is 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 vehicles, 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 vehicles 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. Many maintenance managers have “horror stories” concerning problems with brand new vehicles.
Also, you will 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, drop in demand, etc.). It would create another set of problems if a vehicle fresh off major repairs broke down for an unrelated reason that could have been found in a pre-service inspection.
How much time should you spend on a pre-service inspection? The time spent on a pre-service check depends on fleet policy. Some fleets put in a day and a half on a new semi-tractor; others add a road test and extensive component testing which can push the time to over a week, depending on the detail. The objective is to make sure that every part is tight and in good working condition.
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 vehicle. 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 vehicle 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 the pre-service check, which may seem unimportant. Remember, 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 gate, autogreaser, wheelchair lift, 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 A to Part 396 (included in the Compliance Management and Regulations sections of this manual). Next, be sure to add the work to your pre-service and inspection checklists.
At the end of this unit are examples of maintenance and pre-service checklists. While they are primarily aimed at large property-carrying vehicles, they can be modified for smaller vehicles and passenger-carrying vehicles by adding or removing specific items.