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.