Normal Braking Technique and Proper Use of Air Brakes
Air brakes are not hydraulic brakes
Air must travel from tank to chamber, so there is a lag between pedal and brake. Stopping distance is longer than in a car and grows quickly with speed. Plan stops earlier and leave a bigger following gap.
Three techniques
- Controlled braking: press as hard as you can without locking the wheels and hold it. Steering stays intact and it works with or without ABS.
- Stab braking (non-ABS): brake as hard as possible, release the moment the wheels stop rolling, then reapply.
- Snubbing on downgrades: choose a gear low enough that engine braking holds your speed, then brake firmly to shed about 5 mph, release, and repeat.
Brake fade happens when drums and shoes overheat from constant use: the pedal feels normal but the truck simply does not slow. The cure is prevention - check the brakes at the top of the hill, descend slowly, and if you smell hot brakes, stop and let them cool.
Traps: "fanning" the pedal or riding light pressure down a long grade is exactly how fade and runaway trucks happen. The trailer hand valve is for testing trailer brakes only - never for normal stops and never for parking.
Rule of thumb: brake before the curve, not in it. On a downgrade, if you are braking more than occasionally, you are in too high a gear - downshift and start over.