Bottom Line
Tackling Truck Maintenance
The primary product of The Technology and Maintenance Council is its ‘Recommended Practices’ — solutions to real-world problems in matters relating to trucking equipment, electronics, etc.

Regular readers know I often refer to The Technology and Maintenance Council regarding maintenance. In 47 years, TMC has grown to become the single leading source of up-to-date, correct information on shop practices, equipment, fuel economy and, since embracing technology’s contributions to trucking, all matters relating to trucking equipment and electronics.

The council is composed of trucking equipment professionals responsible for anywhere from 10,000 vehicles or more down to just one truck. Regular readers of Land Line know that OOIDA members Mike and Gail Swiger are both study group chairpersons. Swiger Trucking has one vote on council matters, just as Yellow, FedEx, the Postal Service and Schneider each have one vote. The votes are important, if for no other reason than to approve the council’s primary product, “Recommended Practices.”

The RPs are solutions to real-world problems. Problems are brought to the group’s attention by truck operators assigned to one of 15 permanent study groups depending on subject matter. Task forces composed of truck operators and industry suppliers work together to develop recommendations for practices and procedures to solve the problems. Their RPs are presented to the membership to be voted on for formal adoption. They are considered the best way to solve each particular problem.

The latest published version of the TMC RP manual is 4 inches thick, with a three-quarters-inch supplement. Later this year, a new edition should be out, incorporating all current RPs.

Why am I telling you this? Because if you own or operate a truck, even if you have your maintenance outsourced, you could benefit by owning a copy of this reference book. If you are a TMC member, it costs $140. For non-members, it’s $195. Just about every fleet of any consequence has a copy in most of its shops. It’s the one reference source to go to before deciding on how to proceed with any repairs, or before purchasing replacement parts.

Here are some practical examples. They may address a problem you may be having right now.

Ride comfort
RP214 from the Tire and Wheel Study Group address ride complaints. Tire and wheel-end balance and runout problems lead to driver discomfort, poor tire life and mechanical failures.

The RP offers balance and runout guidelines for each major component in the rotating assembly. It covers the proper assembly of components, tire-mounting procedures, and procedures for checking runout and balance.

Imbalance is the unequal distribution of weight about the axis of rotation. Static imbalance causes wheels to bounce. Dynamic imbalance causes them to wobble or shimmy. If a wheel/tire assembly is dynamically balanced, it must also be statically balanced, but static balance alone does not ensure dynamic balance.

Runout is a visible, measurable out-of-round movement, often caused by poor tire-mounting practices. The RP shows how to easily measure whether tire runout is present without having to rotate the tire. Simply measure the distance from the mold ring to the rim every 90 degrees around the tire. Any variance greater than 2/32nds of an inch is too much. The tire then needs to be remounted and rebalanced.

The simplest way to tell if vibration complaints, often caused by runout, are coming from the steer or drive axles is where you feel them. If it’s in your seat, it’s a drive tire. If it’s in your feet, it’s a steer tire.

Sensor signals
Have you ever gotten a “ghost signal” from a sensor? They show up as flashing warning lights, but when you go to check, no problem shows on the download from the engine control unit (ECU). There could be a ghost problem, an intermittent sensor fault or a poor ground or connection, or a real, physical problem. How do you know, and what do you do?

RP1209 addresses the maintenance and diagnostics of truck sensors. Developed by the On-Board Vehicle Electronics Study Group, it provides diagnostic methods for all types of sensors, including fan control, temperature sensors of all types, fuel level sensors, pressure sensors, wheel speed/antilock brake sensors, throttle position and vehicle speed sensors.

The RP differentiates between electro-mechanical and electronic sensors, and provides precise procedures from each major component supplier for its products.

Temperature sensors “can be checked for proper operation by monitoring resistance across the terminals at a known temperature. Manufacturers publish a resistance range at room temperature which helps technicians identify whether the sensor is bad or not.” Be sure to use the right table for your components, since values vary between makes.

Some sensors are based on industry standards. Fuel level sensor systems, for example, are either 90 ohms or 240 ohms. RP1209 provides values for full, half and empty tanks. Engine control sensors are usually proprietary.

Pressure sensors protect and control. They protect by informing control systems when pressures are within safe or proper operating ranges. When used for control, they provide data used to maintain pressure or regulate other functions. The RP identifies 27 different types of pressure sensors found on trucks, from fuel delivery pressure to fuel injector rail pressure, from transmission oil pressure to coolant filter differential pressure, from atmospheric pressure to turbo boost pressure.

Most diagnostics can be performed using a volt/ohm meter or a multi-meter, and a “breakout plug” that lets you connect to the sensors. The RP gives instructions on how to make one. Specific instructions are also given for testing each engine maker’s specific sensors. Schematic diagrams are included.

The RP also provides a general troubleshooting guide.

Towing and recovery
I often hear complaints from drivers regarding the all-over-the-board fees associated with towing and recovery services. Basic fees that are quoted may seem more than competitive, but add-ons and extras can raise the bill substantially, often by thousands of dollars.

The Fleet Maintenance Management Study Group developed RP527, Vendor Selection Guidelines for Towing and Recovery, in order to qualify vendors and avoid ups and extras. There is a list of 20 questions, covering everything from proper insurance, licenses and permits to storage facilities for trailers and extra charges. Have they quoted daytime rates, but have after-hours rates too? What time does overtime kick in? What are their surcharges or extra fees, such as hook-up fees and hazmat surcharges?

By using RP527 as a checklist, you can avoid unnecessary costs and potential damage to your equipment.

Tire tread selection
Everyone needs to replace tires. When it’s time for you to, what type of tread will you select? Will it be what your favorite vendor has in stock, or will it be the optimum one for your operation?

The Tire and Wheel Study Group developed RP220, Tire Tread Design Selection, to answer those questions. The RP discusses highway rib tires, highway traction tires, on/off highway rib tires and on/off highway lug tires. Charts match various user needs, such as fuel economy, steering response, wet or dry traction and wear resistance, with various tire properties, such as tread depth and pattern. Criteria are discussed, so buyers can make educated choices.

These are just a few of the TMC RPs that provide useful, practical information. There are many more, covering almost everything you need to know or do.

But trucking is a dynamic industry, with change being its only constant. That’s why there are currently 73 task forces developing new RPs on the maintenance side alone, with another 20 to 30 reviewing and updating existing ones.

It’s also why, in the past few years, TMC added two new study groups, one on vocational trucks and one on vehicle and cargo security.

—by Paul Abelson, technical editor Paul is a 20-year TMC member. He can be reached at