Pre-Trip Inspection and Daily Air Brake Checks
Build a repeatable walk-around
A pre-trip is a sequence, not a memory test. Work from the front of the vehicle to the rear and check air system items as you go:
- Compressor belt condition and tension, and obvious oil or coolant leaks.
- Air dryer mounting, fittings and discharge; note whether the purge sounds normal.
- Reservoirs: drain each tank at the drain cock and watch for moisture, oil or sludge. A small initial spurt of water is normal; a steady flow of oil means trouble.
- Lines and hoses: chafing, cracks, rub points, secure glad hands and couplers.
- Chambers and slack adjusters: bent or broken pushrods, loose clamps, missing cotter pins, lining and drum condition.
- Low-pressure warning device and gauge operation.
- Parking brake holds, and the tractor protection/trailer supply valves work.
Then complete the performance tests: buildup, leakage released, leakage applied, low-pressure warning and spring brake application. Only then move the vehicle, and make a low-speed brake test before entering traffic.
Traps
- Draining tanks with the engine running just refills them; drain at full pressure and engine off.
- A wet tank that always contains water points to a dryer problem - do not simply drain and forget.
- Automatic slack adjusters and automatic drain valves still get inspected.
- Missing or damaged chamber clamps and loose pushrods are out-of-service items.
Rule of thumb: if you cannot complete the buildup, leak and warning tests in a few minutes with normal results, the vehicle does not leave the yard. A defect you find on the pre-trip is cheap; the same defect downhill is not.