Issue link: http://read.dmtmag.com/i/34501
BRAKING SYSTEMS AND ISSUES Air brake issues as they apply to tire wear and damages can result from imbalance or component concerns. Distorted, brittle, and/or discolored rubber in the bead area are signs of the “outside to inside” breakdown of rubber products as a result of seating on a wheel surface, which is heated to a temperature beyond the limit that the rubber products can tolerate. This damage starts at a temperature in the mid-200 degree Fahrenheit range, with accelerated damage occurring above the 300 degree Fahrenheit range. 1. Brake imbalance can be the result of the air system, including valves, not actuating the brakes simultaneously. This may be the result of dirt, leaks, and/or valve cracking pressure. In a tractor/trailer combination, the more rapid brake application time now being used (up to twice as fast as pre FMVSS*-121 systems) can result in a brake imbalance due to combinations of old tractors with new trailers or new tractors with old trailers. 2. Component situations, such as out-of-round brake drums or unevenly worn brake shoes, also result in tires acquiring odd wear and flat spots. 3. Another source of brake imbalance is the improperly adjusted slack adjuster. Any of these brake imbalance situations can result in one or more wheel positions locking up and flat spotting the tires. 4. Brake drums with balance weights thrown may result in ride disturbance. 5. Brake lock (flat spots) conditions may be evidence of deficiency in the Anti-Lock Brake System. *FMVSS - Federal Motor Vehicle Safety Standards SUMMARY OF TIRE ISSUES DUE TO BRAKES Problem Possible Causes 1. Overuse on down grades due to improper gear. Brake Heat 2. Brake dragging due to mis-adjustment of wheel bearings. 3. Repeated stops without cooling time. 4. Improper adjustment or braking balance leads to excessive amount of braking in one or more wheel positions. 1. Out-of-round brake assembly. Lock Up 2. Slow release valves. 3. Mis-adjustment slack adjusters. 4. Brake drum runout. Brake Lock 56 Section Three: Extending Tire Life Brake Heat Brake Heat Result Brake Lock Bead damage to the tire ranging from simple distortion to complete unwrapping of the casing from the bead wire. Flat spots and odd wear.