It is more important today than ever before to make sure that our dollar stretches as far as possible. A proper alignment of your truck will save you money on fuel costs and help you get additional mileage from your tires.
The reduction in operating costs will help you be more competitive in the marketplace and add more dollars to your bottom line.
Millions of dollars are spent on streamlining truck shells, improving drivetrains and designing energy-efficient engines. Yet, many trucking industry professionals neglect one of the most effective ways to reduce operating costs: total wheel alignment.
There are a number of common signs of misalignment, including:
Excessive tire wear.
Increased fuel consumption caused by increased rolling resistance.
Unsafe vehicle handling characteristics.
Driver fatigue caused by constantly correcting the direction of the vehicle.
Premature suspension component wear.
One of the most critical factors in front-end tire wear is drive axle misalignment. (See Diagram 1.) Therefore, performing an alignment only on the steer axle is not enough. A misaligned drive axle affects all the wheels on the vehicle.
It is estimated that over 70 percent of the heavy trucks on the road have tandem axles that are misaligned. To keep the truck going straight, the turning force of the misaligned tandem must be offset by turning the front wheels in the opposite direction. This causes all ten wheels to scrub mile after mile.
Total wheel alignment minimizes rolling resistance caused by misalignment, reducing tire wear and fuel consumption.
Don’t forget trailer alignment. A misaligned trailer forces the driver of a properly aligned tractor to correct for the pull caused by the trailer, resulting in tractor tire wear.
In Diagram 2, the truck has toe misalignment on the drive axle of only 0.10 inches (or 0.06 degrees). If the truck travels 125,000 miles a year, the resulting effect would be equivalent to dragging the tires sideways for 100 miles. Think of the impact of such a small misalignment on tire and fuel consumption and then multiply that by the number of tractors and trailers in your fleet.
According to materials from the Technology and Maintenance Council, a scheduled alignment program will produce an average 30 percent increase in tire mileage and an average two percent increase in fuel economy.
Here’s what total wheel alignment can do for your fleet’s performance:
Reduce tire wear. Improper alignment is a major cause of premature tire wear on all axles. Total alignment sets all wheels parallel and, can add thousands of miles to tire life.
Reduce component wear. When all wheels work with the system, stress on steering and suspension components is drastically reduced.
Spot problems early. An under-vehicle inspection is a critical part of any alignment procedure. This provides an opportunity to spot worn parts before more costly problems arise.
Improve handling. Proper alignment is necessary for optimum handling characteristics - contributing to increased safety and reduced driver fatigue, especially on ice and snow.
Minimize rolling resistance. Total alignment sets all wheels parallel. This works with proper inflation to minimize rolling resistance and improve operating efficiency, which helps reduce fuel consumption.
When it is time to get your truck aligned, many terms are used to describe the process. At times, this may be confusing. Here are most of the terms, separated into three major categories, which you will need to know to be a part of the conversation:
Drag link - A tube or rod used for interconnection between the pitman arm and tie rod assemblies.
King pin - A pin used to attach a spindle to an axle.
Tie rod - The outer most assemblies on the steering linkage.
Cross tube assembly - Two tie rods and a tube which transfer the turning effort to the opposite site of the vehicle.
Degree - A unit of measure to describe an angle.
Caster - The forward or rearward tilt of the steering axis.
Centerline steering - A centered steering wheel while the vehicle is traveling a straight ahead course.
Offset - The lateral displacement of a wheel or axle in respect to the center line.
Toe - The comparison of a horizontal line drawn through both wheels of the same axle.
Tandem scrub angle - The angle formed by the intersection of horizontal lines drawn. through each rear axle when total toe and the offset is zero.
Thrust angle - The angle formed by thrust line and geometric centerline.
Thrust line - A bisector of rear total toe.
Symptoms of improper alignment:
Pull - The tendency for a vehicle to steer away from its directed course.
Lead - A slight tendency for a vehicle to move away from its directed course.
Vibration - To consistently oscillate at a specific frequency.
Waddle - The lateral movement of a vehicle, usually caused by some type of tire or wheel imperfection.
Wander - The tendency of a vehicle to drift to either side of its directed course.
Routine wheel alignment is the most effective way to control tire costs and fuel costs. Yet, wheel alignment is commonly addressed after costly damage has been done to the vehicle.
As you establish and update your alignment schedule, it is recommended that two or three alignments per year or every 50,000 to 60,000 miles be performed as a part of your preventative maintenance program.
Jerry Bodkins, an ASE Master Certified Technician for the past 10 years, is a technical trainer with TravelCenters of America/Petro. His training responsibilities include, helping technicians prepare for their ASE Master certifications, especially in the areas of electrical systems, brakes and air conditioning. Bodkins has represented TA/Petro at a TMCSuperTech, the National Technician Skills Competition, and was a winner at the event’s Tires and Wheel Skills Station. TA/Petro is the largest full-service travel center network in North America. TA Truck Service and Petro Lube currently have a combined total of 224 locations across the country, all open seven days a week and staffed with ASE certified technicians.