Every fleet manager is interested in minimizing his fleet’s operating costs. But some fail to understand the importance of gaining every bit of service life out of equipment that’s economically possible? That’s true, of course, for trucks, tractors and trailers, but it’s also true for the parts that make up a fleet’s rolling assets.
Some parts are designed to wear as they deliver service – think of brake shoes and drums. Other parts, while not actually designed to wear away, can be expected to deteriorate over time and will need to be replaced periodically. Determining replacement cycles and brands to be used is up to the fleet manager. Making good “when and with what” decisions will result in those items delivering their maximum service and return on investment.
Inflated heavy-duty tire and wheel assemblies can be dangerous, lethal in fact, if they are not handled properly. According to Alcoa’s Wheel Service Manual, statistics indicate that in most industries only one in 1,000 serious accidents results in a fatality. However, when the event involves tires and wheels, one in every 10 serious accidents is a fatality, 100 times more often.
This is why OSHA has written regulations that apply to even the smallest shops involved with tire and wheel work. Tire dealers and fleet maintenance managers should to their charges to pay particular attention during any of these crucial service steps:
• Removal of tire/wheel assemblies from vehicles
• Demounting tires from wheels
• Tire/wheel inspections
• Tire inflation
• Handling and storing of inflated assemblies
Pertinent OSHA regulations are contained in 29 CFR Section 1910.177. Included in the section is the statement, “The employer shall provide a program to train all employees who service wheels in the hazards involved in servicing those wheels and the safety procedures to be followed. The employer shall assure that no employee services any wheel unless the employee has been trained and instructed in correct procedures of servicing the type of wheel being serviced.” The Tire Industry Association (tireindustry.org) has available a substantial collection of training programs specific to handling today’s truck tires and wheels.
To maximize service life, wheel end components, including brake drums and wheels, should be inspected regularly. While it is not possible to predict its useful life, a wheel will wear out eventually, especially if they are operating in severe conditions. All wheels – new and old – should be inspected for signs that they should be removed from service.
Alcoa service engineers recommend examining all exposed wheel areas frequently, while cleaning the wheels, look for cracks, corrosion, wear or other damage. Also check the inner wheel of a set of duals when the outer wheel is removed. During tire changes, thoroughly examine the entire wheel. Pay particular attention to the rim contour and the surfaces of the rim edge.
Since some forms of wheel damage can be hidden beneath the tire, thoroughly examine the complete wheel whenever a tire is removed. Clean off all grease and road dirt, and use a wire brush or steel wool to remove any rubber from the bead seats. Check mounting holes for damage, enlargement or elongation, which can occur if the cap nuts are not kept tight. Dirt streaks radiating from stud holes may indicate loose cap nuts.
Aluminum wheels are very robust. When used properly, they can easily last the life of the truck or trailer. Alcoa claims that its warranty claims are very low, and the few warranty claims they do receive are often due to overloading or improper loading of equipment. Alcoa wheels include load ratings, and a heat-sensitive sticker. Overloaded tire/wheel asemblies create damaging heat. When the temperature threshold is compromised, the sticker indicates the breach of heat limit and the wheel must be replaced.”
Accuride, a supplier of both steel and aluminum wheels, recommends looking for signs of cracks and rust lines (for steel wheels) originating from bolt holes, as these are common signs of low clamping force. It is also important to pay close attention of wheel studs. Clean them regularly. Rust and corrosion should be removed from all mounting surfaces on the wheel, hub, drum and studs. Also remove burrs on or around the bolt holes or center holes.
Says one expert at Accuride, “Pay attention to twheel fastener orque, both under-torque and over-torque. In the case of the latter, over-torque can also compromise the life of the mounting stud. This is especially important after wheel rotations.
“Another concern is when steel wheels are being refinished because of corrosion. When a steel wheel is repainted, the original finish is normally removed by sandblasting. Unfortunately, there are times when some of the original paint remains on the surface, which can cause false torque readings.”
A manager at Motor Wheel says, “We advise that wheels be initially tightened to the upper limit of 500 ft.-lb. After 50 to 100 miles of operation, the wheel nuts should be checked for tightness and when necessary. A torque check should also be made part of the vehicle’s scheduled maintenance program or at 10,000 mile intervals, whichever comes first.”
Remember, if a stud is broken, also replace the adjacent studs on either side of the broken stud. If two or more studs are broken, all of the studs on that wheel must be replaced, he says.
Consistent, reliable brake system performance is dependent on a sound brake system maintenance program, including a regular inspection of brake drums. Different trucking applications put a wide variety of demands on brake systems. Consider line-haul versus refuse fleets; there is no industry-wide timetable for brake system inspections, as such a regular inspection program should be established on a fleet-by-fleet basis depending upon the demands the operation puts on its vehicle’s braking systems.
Gunite service engineers offer information on some common problems encountered during brake drum inspections.
Cracked drums – a drum with a crack extending through the entire wall must be replaced. This condition may indicate driver abuse, if the brake system components are correctly rated for the application.
Heat checking – numerous short, fine, hairline cracks on the braking surface of the drum is a normal condition. However, it is advisable to make sure that deep cracks have not developed.
Grease-stained drums – will show discolored spots on the braking surface with oil and/or grease spattered on the brake assembly. The source of the contaminant must be located and eliminated. Remove the entire brake assembly and clean each component thoroughly. If the linings are soaked, they must be replaced.
Martensite spotted drums – with hard, slightly raised dark colored spots on the braking surface with uneven wear indicates that the drum has been subjected to extremely high temperatures caused by an improperly balanced braking system, a dragging brake or continued severe brake applications. The drum must be replaced, then the entire braking system checked for proper balance between the tractor and the trailer as well as wheel to wheel.
Blue drums – have been subjected to extremely high service temperatures. This condition may be caused by continued hard stops, by brake system imbalance or improperly functioning return springs. To correct this problem, the brake system should be checked for proper balance. The return springs should be checked to determine if they are weak or broken. The brake should be checked for proper adjustment and clearance.
Polished drums – can easily be solved by sanding the braking surface with 80 grit emery cloth. It is also necessary to remove the glaze from the linings at the same time using the same emery cloth. The brake system should be checked for lightly dragging brake(s) as well as the linings to make sure that they have the correct friction rating.
A product manager for the Gunite product line at Accuride, says, “When our warranty department gets complaints from the field, they are usually the result of the product choices fleets have made. When fleets look to replace drums on their vehicles, they may, in some cases, not select the appropriate drum for their application. Low cost does not always mean that the fleet will save money in the long run. An operator that is looking only for a minimum price weight drum and not looking at the application in which that drum will be used may well see a performance reduction. Fleets need to make the correct choice for the application at the start so they aren’t scrambling later to solve a more expensive problem later.”
Another parts manager echoes that same thought, but with the caution, “With discount brake drums, our dealers often see out-of-round conditions resulting from poor manufacturing. This can lead to vibration, which can significantly reduce tire life and cause many other issues with brakes and suspensions.
“Brake drum manufacturers that don’t follow a rigorous quality-control process during manufacturing often take short cuts, leading to the production of oblong or out-of-round brake drums. If they are out-of-round new, they aren’t going to get beter no matter what you do.”
What to Buy
Because of the many things medium and heavy trucks are asked to do, there is no such thing as a “one-size-fits-all” choice when it comes to either wheels or brake drums. Light weight will save fuel or offer greater payload potential so that may be a reasonable option if your equipment never has to leave good roads. However, in mixed on-/off-highway applications, it is important to use the correct wheel for their equipment.
Replacement parts should meet all associated SAE or FMVSS recommended guidelines for quality. These documents can be easily found online.
As one supplier says, “Look for replacement parts with warranties backed by a reputable OEM. While value is a big consideration when choosing OEM-produced replacement parts, quality and proper fit must also be part of the equation.”
If lightweight makes sense in your operation, you’re now faced with the choice between premium steel and aluminum wheels. Even the lightest steel wheels are heavier than aluminum, but the cost differential demanded by aluminum may be a hard nut for some fleets especially when steel wheel suppliers keep offering new cost saving options.
New coating – steel and aluminum – bring the promise of reduced corrosion, improved durability, and vastly improved “look.” Some even claim they can extend the service life of aluminum wheels by at least two years.
Getting two or more years of additional service life out of a wheel means sharply reduced operating costs, nothing to sneeze at for any size fleet.
Lighter and lighter wheels – steel and aluminum – help fleets get every cent-per-mile out of their fuel tanks. Diesel may not cost $4 a gallon at the moment, but less wheel weight means more haul weight.
“Fleets looking to take weight out of their equipment in order to haul more can achieve this advantage by shifting to lighter weight aluminum wheels,” says one supplier.
In the most extreme scenario, shifting an 18-wheeler from steel dual (22.5×8.25-inch) tires/wheels to aluminum 14-inch super wide base wheels and tires saves 1,400 pounds on the rig. That’s 1,400 pounds more freight that can be hauled. The pay-off against the investment can be achieved quickly and the savings are enjoyed over the life of the truck or trailer.
There are some decisions that only you can decide. If you take those 1,400 pounds out of a combination, will you be able to add 1,400 pounds of cargo? If you pull tankers, probably. If you pull dry vans, maybe not. If not, will you be able to get a pay back through fuel savings?
OEMs can help you answer such questions. Don’t hesitate to ask them. Every day, new products are being introduced that can help make your operation more competitive if applied effectively.