Brake problems are consistently near the top of the list of reasons trucks get parked at roadside inspections, and the air system is behind a lot of them.
East Tennessee terrain works brakes hard. A loaded truck coming down off the plateau on I-40, down the grades on I-75 south of Jellico, or through the Pigeon River Gorge is leaning on its foundation brakes for miles. That wears shoes and drums, cooks linings, and shows up every weak slack adjuster. In winter, moisture in the air system can freeze in lines and valves, and brine spray corrodes fittings and gladhands.
We come to the truck to find the leak, replace what failed, and make sure the system builds, holds, and releases air the way it should.
What’s included with our Air Brake Service
- Finding and fixing air leaks at lines, fittings, valves, and tanks
- Gladhand seals and gladhand replacement
- Trailer air lines — red emergency and blue service — and line hangers
- Brake chamber replacement, including spring brake chambers
- Slack adjuster inspection and replacement, plus pushrod stroke checks
- Brake shoe and drum inspection, and replacement where access allows
- S-cams, cam bushings, and brake hardware
- Air dryer and purge valve service, including desiccant cartridge replacement
- Governor testing and replacement
- Air compressor diagnosis — slow build-up, oil in the system, or no air
- Relay, quick release, tractor protection, and foot valve leaks
- Draining tanks and checking for oil or water contamination
- ABS lamps and wheel speed sensor faults on tractors and trailers
What needs a shop instead
- Compressor replacement on engines where it means pulling major components — doable on some trucks, a shop job on others
- Brake jobs on wheel ends with seized hardware or damaged hubs that need heavy teardown
- Drum machining
- Full brake overhauls on several axles at once, which are more efficient in a shop
Don’t cage a spring brake to move a truck unless you’re trained to and sure you still have enough braking. Caging disables that brake.
Repair it where it sits, or tow it?
Most air brake problems are fixed on site: leaking lines and fittings, gladhands, chambers, slack adjusters, air dryers, and valves are standard mobile work. A truck that can’t release its brakes because of a leak is often repaired and driven away the same visit.
A tow is the better choice when a wheel end is badly damaged, when the compressor failed on an engine where roadside replacement isn’t practical, or when a brake failure caused other damage. Never drive a truck with a known air system failure that affects braking — especially not toward a downgrade.
Have this ready when you call
A few details up front help the mechanic load the right parts and tools and get it done in one trip.
- Whether the low-air warning is on, and what pressure the gauges show
- Whether the brakes won’t release, won’t apply, or are dragging
- Where you hear the leak — tractor or trailer, front or back — and whether it leaks with the brakes applied or released
- Whether it started right after hooking a trailer, or after a cold night
- If the truck was put out of service, the violations on the inspection report
Makes & engines we work on
- Freightliner
- Peterbilt
- Kenworth
- Volvo
- Mack
- International
- Western Star
Class 6 through Class 8 trucks, including engines from Cummins, Detroit Diesel, PACCAR, Volvo, Mack, Navistar, and Caterpillar.
Air Brake Service around Knoxville & East Tennessee
Air brake calls come from yards and drop lots where trailers get hooked and dropped all day, from the truck stops at the bottom of long grades, and from the Knox County weigh station on I-40/I-75 near mile marker 372, where inspections turn up brake adjustment and air leak problems.
Highways we cover
Towns we cover
- Knoxville
- Farragut
- Maryville & Alcoa
- Oak Ridge
- Clinton
- Lenoir City & Loudon
- Sevierville & Pigeon Forge
- Morristown
Air Brake Service: common questions
How do I find my air leak?
Listen with the engine off. A leak with the brakes released points to the supply side — lines, tanks, and valves. A leak only with the brakes applied points to service chambers, the foot valve, or relay valves. Our air leak guide walks through it.
Why won’t my trailer brakes release?
Usually low air from a leak, damaged or crossed gladhand connections, a failed spring brake chamber, or a problem with the trailer’s relay emergency valve. In winter, ice in a line or valve can do it too.
What does “brake out of adjustment” mean?
Each chamber size has a maximum allowed pushrod stroke. Past that limit, the brake loses effectiveness. Automatic slack adjusters are supposed to prevent it, so an out-of-adjustment brake usually means a slack or foundation brake part needs attention.
Should I adjust automatic slacks by hand?
Routinely hand-adjusting automatic slack adjusters hides the real problem. If one keeps going out of adjustment, the brake should be inspected to find out why.
Is oil or water in my air tanks a problem?
Some moisture is normal, but a lot of water means the air dryer isn’t doing its job — and in winter that water can freeze in lines and valves. Oil suggests the compressor is passing oil. Both damage valves and seals over time.
Can you fix brakes so an out-of-service truck can move?
Brake-related out-of-service defects can often be repaired where the truck was stopped. Keep the inspection report handy and ask for an itemized repair record.