What is the 'fanning' or 'snubbing' braking technique and when should it be used?

SNUBBING (also called CONTROLLED BRAKING or brake fanning) is an approved technique for descending long grades.

How it works: Apply service brakes firmly until vehicle speed decreases by approximately 5 mph (for example, from 30 mph to 25 mph); COMPLETELY RELEASE brakes — allowing drums and pads to cool through airflow and conduction; wait until speed returns to starting point (30 mph in the example); reapply brakes and repeat.

Why it works: Each brake application generates heat in the drums/discs and lining. During the release phase, airflow over the drums carries this heat away. By releasing completely, the cooling cycle is maximized. 'Riding' the brakes (light continuous application) generates heat without allowing cooling, leading to brake fade much faster.

The key principle: It is always better to use brakes hard for short periods with full recovery between applications than to use them lightly for extended periods without recovery.

Contrast with the wrong approach: Many drivers instinctively apply light brake pressure to 'hold' their speed on a grade. This is precisely backward — light continuous application is the fastest path to brake fade.

Selecting the correct speed: Snubbing works best when you select a speed that allows you to control the 5 mph cycles comfortably. If the truck is constantly accelerating and the cycles get shorter and shorter, your speed is too high for that grade — you need engine braking in a lower gear.