What is the correct technique for emergency braking in a straight line when a CMV does NOT have ABS?

For CMVs WITHOUT ABS (increasingly rare, as ABS is required on new vehicles, but older equipment may lack it), emergency braking is a skill requiring technique.

The problem with locking wheels: When a wheel locks (skids), friction actually decreases compared to a rolling wheel, AND steering control is lost — the wheel can only push the vehicle in one direction (straight). For front wheels, locking means loss of steering; for rear wheels, it means risk of jackknife (articulated vehicles).

Two approved techniques: (1) THRESHOLD BRAKING: Apply brake pressure gradually to the maximum point just before wheels lock — this 'threshold' gives maximum stopping force while maintaining rolling traction. Requires experience and feel; sense of wheel lockup through pedal feedback or vibration; ease off immediately if lockup occurs. (2) STAB BRAKING: Apply brakes hard (maximum pressure), hold 1/2 to 1 second, then COMPLETELY RELEASE (allowing wheels to roll and steering to return), then immediately REAPPLY; repeat rapidly. This allows brief steering correction between applications.

Important: Do NOT pump the brakes slowly — this wastes too much stopping distance. MODERN CMVs WITH ABS: Modulation is handled electronically; driver applies maximum pressure and maintains it; ABS cycles the brakes at the threshold automatically; steering is maintained. Check for ABS by looking for the ABS warning light on the dashboard (required indicator) or the yellow ABS lamp on the trailer.