While descending a steep mountain grade, a driver observes that the vehicle has accelerated to its established safe speed of . In what sequential order should the driver perform the following actions to execute one full cycle of the snub braking technique?
- 1Apply the service brakes with firm, steady pressure to produce a definite slowdown.
- 2Maintain brake application for approximately three seconds until vehicle speed drops to ( below safe speed).
- 3Release the service brakes completely once the reduced target speed is reached.
- 4Allow vehicle momentum in low gear to accelerate the vehicle back up to the safe speed of before repeating the application.
Answer
The correct sequence is: (1) Apply the service brakes with firm, steady pressure to produce a definite slowdown, (2) Maintain brake application for approximately three seconds until vehicle speed drops to 35 mph (5 mph below safe speed), (3) Release the service brakes completely once the reduced target speed is reached, and (4) Allow vehicle momentum in low gear to accelerate the vehicle back up to the safe speed of 40 mph before repeating the application.
According to the official CDL mountain driving guidelines, the snub braking technique is performed in four distinct stages: first, applying the brakes firmly to feel a definite slowdown once safe speed is reached; second, holding the application for approximately 3 seconds until speed drops to 5 mph below safe speed (from 40 mph down to 35 mph); third, fully releasing the brakes to allow the lining and drums to cool; and fourth, letting gravity and momentum accelerate the vehicle back to the safe speed before repeating the sequence.
Step-by-Step Solution
Key Concept
Snub braking technique on steep downgrades
Estimated Time:1m 15s