Total vehicle alignment maintenance and inspection programs pay numerous dividends, industry research finds. These include:
- Extended tire wear.
- Enhanced fuel economy.
- Decreased component wear.
- Greater uptime.
- Improved driver comfort.
- Safer vehicles.
Yet, industry experts estimate that some 70 percent of Class 8 trucks on the road today have alignment problems.
Vehicle and wheel alignment settings serve a variety of functions in vehicle operation. Among other things, they affect handling, control, stability, performance and safety. When a vehicle is in total alignment, all wheels “agree” on one direction – focused on the frame – so there are no lateral forces to create a countersteering effect.
VEHICLE GEOMETRY
A vehicle is a composite with the chassis as the foundation, says Dutch Johnson, training and manager, Josam Products (www.josamusa.com), a world manufacturer of heavy duty truck frame, axle and wheel alignment equipment. This foundation must be square and solid to support the dynamics of the complete structure.
The chassis, he says, includes every wheel, axle, suspension component and frame member. All should be aligned in relation to one another as a whole.
Total alignment is a correction of the entire vehicle geometry instead of only one wheel or one axle independently, adds Nick McCullough, president, RAV America (www.ravamerica.com), a distributor of Ravaglioli wheel alignment machines, wheel balancers, tire balancers, tire changers and vehicle lifts. The complete rectangle is considered, with the alignment performed in stages, usually one axle at a time.
A vehicle not in proper alignment “is a recipe for a maintenance manager’s nightmare,” says Greg Brock, heavy duty equipment specialist, Hunter Engineering Company (www.hunter.com), a manufacturer of passenger car and truck service equipment, including alignment systems, wheel and tire service, brake service and inspection lane equipment.
The most important breakthrough in modern alignment equipment is the ability to perform ultra-fast checks of the alignment condition of the vehicle, McCullough points out.
McCullough says: “This allows the maintenance team to now do what they always knew needed to be done but could not.
“Now it is feasible to perform alignment tests and correction not once during the life of the steering tires, but five to six times at regular oil and lube cycles. Toe condition changes constantly on the steer axle. By checking and re-adjusting the toe angle every 25,000 miles, you can expect much longer steer tire life and, therefore, lower tire costs.”
“Often times, the difference between a ‘good’ truck and a ‘bad’ truck is simply one that handles well due to proper alignment,” Josam Products’ Johnson says.
MAINTENANCE EXPENDITURES
When a vehicle is aligned improperly, the two largest maintenance expenditures – tires and fuel – are impacted the most, says Hunter Engineering’s Brock. Misaligned axles cause the tires to be scrubbed across the pavement, leading to uneven tire wear for a shorter life expectancy.
Scrubbing also increases rolling resistance, which directly impacts fuel consumption.
Tires that have to be taken out of service prematurely do not provide the proper return on investment, especially if they are no longer an acceptable tire casing for retreading.
DRIVE AXLES
“Based on our experience working with tire companies and fleets, 50 percent of irregular wear on steer tires is from alignment and the other 50 percent is caused by other things,” says Michael Beckett, president, M.D. Alignment Services (www.mdalign.com), a company that offers alignment equipment for heavy trucks and trailers, along with alignment training and consulting. “On trailers and drive axles, 10 percent of wear issues come from alignment and 90 percent from other issues.”
All of the engine horsepower and three-quarters of all the weight carried on the power unit is on the drive wheels, he explains.
“Until you get the drive wheels pushing in the direction you it to go, all you are doing in the front end is trying to overcome that power,” Beckett says.
Johnson of Josam Products notes that a vehicle going down the road sideways negates any aerodynamic aids intended to help it slice through the wind efficiently.
“A misaligned vehicle is anything but ‘green’ and works counter to the all of the aspects of the creed,” Johnson says.
“A recent discovery of ours is that a significant cause of outside shoulder wear on right front tires is from a change in the design of the steering linkage,” M.D. Alignment Services’ Beckett notes. “This change allows the steer wheels to turn 55 degrees from the traditional 40 degrees and increments between the two. The further the wheels turn past 40 degrees, the more rapid the onset of the wear pattern.”
IMPACT ON THE DRIVER
Improper vehicle alignment also has an impact on the driver. When a vehicle is not in alignment, the driver will be constantly correcting the steering and that could become a factor that will impact safety.
A consequence of improper vehicle alignment are tired, frustrated, ineffective drivers who are unsafe and less productive. Poor handling vehicles are a reason for a driver to start looking for employment at another company.
Properly aligned vehicles are not only safer to drive, but make driving easier and enjoyable.
SCRUTINY
Proper and routine inspection of the tires for early stage irregular wear should be a part of any regular preventive maintenance (PM) practice, advises Beckett of M.D. Alignment Services.
He feels there is no need to measure vehicle alignment on a scheduled PM basis as this “does no more good than dismantling the truck engine to inspect the gaskets. If the gaskets are not leaking they are just fine. By the same token, if the tires are wearing correctly, the alignment is alright.”
Others feel that measuring and correcting alignment should be performed for all power units and trailers as a part of the PM program, although mileage intervals vary.
“This will maintain effective cost per mile expenditures for both fuel and tires,” says Hunter Engineering’s Brock.
RAV America’s McCullough says checks at regular intervals are necessary because vehicle suspensions are flexible and, therefore, the alignment will change due to the G forces emitted by the powertrain.
McCullough says: “Regular alignment checks enable correction of any adverse changes in the vehicle geometry due to wear and tear.
“The choice that a fleet must make is whether to be proactive with a dedicated alignment program or to be reactive and align a vehicle when tire wear takes place and is obvious. One method maximizes vehicles tire life and fuel economy; the other does not.”
Along with periodic vehicle alignment, Josam Products’ Johnson recommends performing a total vehicle alignment every time a suspension or steering part that affects alignment is changed. This, he says, should be:
- The final step in an accident repair process.
- When steer tires are changed.
- As a response to driver handling complaints.
- When the straight ahead position of the steer wheel changes.
He also recommends following the Technology and Maintenance Council’s Recommended Practice 642, Total Vehicle Alignment, which provides guidelines for alignment intervals.
