The buzz word in the trucking industry today is Big Data or, in another parlance, the Internet of Things (IoT).
These terms engender and, in fact, reinforce the acknowledged importance of technology to our operations and our industry. Old tools such as OBD-II, which dates to 1996, and new tools such as telematics, ELDs, TPMS, and many others, all seem to scream how important data has become in our management toolboxes.
Amidst this avalanche of emphasis on informational technology and hardware, the time-honored techniques, the low-tech nuts-and-bolts of truck and trailer maintenance, are in danger of being diminished or lost.
The reality is, big dollars are lost and unit availability is consistently compromised when our focus is diverted from those low-tech, time-honored shop floor techniques that brought us here in the first place.
This six-part series will explore, or for some revisit, certain aspects of preventive maintenance (PM) which, when practiced consistently, will directly benefit cost control while at the same time enhancing unit availability by reducing breakdowns and extending the intervals between shop visits.
Rather than focusing on PMs in general, this series will focus on the six vehicle systems responsible for the highest percentage of breakdowns and service failures. Adopting the techniques and recommendations in this series can help your PM program become more robust and attain a quality standard that lowers risk and cost exposure while achieving higher vehicle availability.
This group or truck component system is perhaps the most overlooked within the entire PM process. This is a surprising fact since for most fleets, tire costs represent the second-highest operational cost category, exceeded only by fuel.
Why is so little emphasis placed on tire preventive maintenance? Is it because, in the words of a popular advertising campaign, “Tires Ain’t Pretty”? Is it because they seem so low-tech their maintenance practices are presumed to be inadequate? Is it because, unlike all other component systems on a truck, clear DOT guidelines exist for tire wear so high tire costs are simply a fact, even when the guidelines are followed? Or, is it because tires seem like such an obvious component that tire maintenance must be equally obvious and, as such, in need of less attention? Regardless of the reason, robust, low-tech tire PM will mitigate tire expenses, especially when management pays attention.
Fleet managers recognize the importance of inflation management. They understand the importance of proper inflation to tire longevity and safety. Most even have their own horror stories about tire-related road failures and the resulting high costs, downtime, and customer and driver inconveniences; yet so little attention given to inflation accountability.
Within the PM process, the checking and correcting of inflation pressures has an inherent scale of diminished effectiveness depending on wheel position. Steering axle tires are easy to check and receive most of the attention, as they should. The next wheel position, outside duals on a truck or trailer, is almost as easy to check and typically receives the next level of attention.
Let’s face it, the inside duals are truly a pain to check. Their valve stems are hard to find and/or reach and are often not located where they are supposed to be; with disc wheels, access to the inside valve stems is sometimes impossible for that reason. Consequently, inflation pressures for those wheel positions are often left unchecked.
On a dual axle, valve stem position for duals should be 180 degrees opposed to one another. Find the outside tire’s valve stem and the inside tire’s stem should be accessible in the wheel openings 180 degrees from its mate on the outside tire. If this is not the case, a good technician should remove the outside tire and rotate it such that both valve stems are properly positioned. That’s what should happen, but does it?
The acknowledged importance of inflation pressure is a given, but is it a priority in your fleet? Are your employees aware? Checking inflation pressure should not be a PM-only occurrence. Inflation pressures are so important to tire longevity they should be checked and corrected whenever your trucks or trailers are in the shop for any reason. Inflation monitoring should be everyone’s responsibility, not simply a step in an infrequent PM process.
By adopting this practice, you and your management team can audit tire inflation effectiveness by spot checking inflation pressures on your ready line. Walking the ready line with a clipboard and a tire gauge sends that critically important message. Pulling vehicles off the ready line for incorrect inflation and returning them to the shop reinforces that message. Holding staff accountable will cement the importance of inflation pressure among your workforce.
Supervisory personnel can be assigned accountability standards to check shop quality, including inflation pressures, on a regular basis. A good benchmark to follow is making a supervisory requirement to check a minimum of five vehicles per week using a physical checklist submitted weekly.
Inflation gauges are among the most abused tool in a toolbox and can report erroneously. A good practice to consider is to incorporate a gauge testing station within the shop air system and periodically test the inflation gauges being used to ensure their accuracy.
If PMs are performed by an outside vendor, checking inflation pressures at the unit’s return is an excellent measure of vendor quality.
Axle Alignment Concerns
Improper axle alignment will kill tires even faster than improper inflation. Alignment, especially on the steering axles, is easier to check than you may realize, with no equipment.
Although improper alignment on the steering axle tires is visually apparent when alignment is truly “off,” a simple, low-tech test can be utilized by a technician at any time, even when the tires look ok.
By lightly passing a palm (no gloves) across the crown of the tire and the tread ribs, the technician can “feel” if the axle is toed in or out. If resistance is felt on the inside of each tread rib, as if that rib is slightly higher than the outside, the axle is likely toed out. If instead, the outside ribs seem higher, the axle alignment is likely toed in. The degree of resistance on the technician’s palm should prompt the decision regarding whether further measurement is necessary.
Steering axles are the most prone to premature wear due to improper alignment; steering axle alignment should be checked during every PM. Rear suspension alignment, especially in tandem applications, is important but less so than steering wheel positions. Rear tandem alignment — especially in severe-duty applications such as dump, refuse, or off-highway — should be checked annually unless their appearance clearly shows alignment issues. Using a tape measure and an axle extension tool, rear axle alignment can be checked easily. Trailer suspension alignment should also be incorporated during the unit’s annual PM inspection using the same tools.
One low-tech tool and process that has seen less emphasis in recent years is the incorporation of a tire square to ensure duals are supporting the load equally.
A tire square is simply a large 90-degree measuring device. The short leg of the square is positioned across the top of a set of duals with the longer lower leg positioned along the sidewall of the outside tire evenly from top to bottom. This process measures the height of each dual, ensuring one tire and wheel is not bearing a disproportionate share of the load. Tire height should be within a half-inch of the height of its mate.
The square should be used whenever one or both tires are changed on a set of duals to ensure equal load parity across both tires.
Wheel Installation Alignment
The growing use of disc wheels has largely eliminated uneven wheel installation. Uneven installations continue, however, especially on multi-piece wheels. A simple low-tech method of double checking that wheels have been installed correctly should be incorporated for every wheel installation.
Before lowering the wheel/tire to the ground, place a block of wood adjacent to the new installation and spin the wheel slowly while eyeballing the open space between the tire sidewall and the wood. If space is consistent around the entire circumference, the wheel is straight and correctly installed.
Measuring Tread Depth
Another simple tool is a tread depth gauge. Although often overlooked in the PM process, without the benefit of this simple device, how can you truly know if tires meet or exceed DOT standards or know the chances of a tire lasting until the next PM cycle?
If the current process utilizes a PM checklist, consider incorporating a section as shown above if currently absent.
A Barometer for Success
There is one place within any maintenance program where the relative effectiveness of a tire program can always be observed and evaluated. Whether it is concern over tire costs, questions about the quality of a tire program, or a desire for a visual reference on its effectiveness, do not look at the tires currently installed. Instead, inspect the tires in the scrap tire area.
Tire carcasses will tell you all you need to know. They disclose alignment practices, tire replacement history, adherence to DOT standards, recap quality (if recaps are used), tire age, etc. Further and perhaps in concert with the tire supplier, scrap tire inspections can lead to program modifications that result in fewer replacements, greater tire longevity, and lower costs overall.
The next installment will focus on preventing electrical component failures by incorporating robust PM techniques on that critical system.
About the Author:
Bob Stanton, CPM, CPFP is an independent fleet consultant and retired public sector fleet manager with 42 years of experience. He can be reached at firstname.lastname@example.org.