Liquid Surge & Braking Technique
24 free questions, part of the Tanker (N) Endorsement CDL practice test
Liquid surge is the forward and backward wave a partially filled tank creates when you speed up, slow down, or stop, and that moving weight can push your truck in a direction you didn't plan for. The fix is smoother braking: brake early, brake smoothly, and never let off the pedal right at the stop. ELDT.io's free bank has 24 practice questions covering exactly this.
This topic has 24 questions, split into 2 tests of 12-12 questions each:
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Start Class A CDL Theory ($15)Questions about Liquid Surge & Braking Technique
Why is a partially filled tank more dangerous than a full one for surge?
A full tank has almost no room for the liquid to move, so surge is minimal. A partially filled tank gives the liquid room to slosh forward and backward with every speed change, and that moving weight can keep pushing the truck even after you've stopped braking.
What's the safest way to brake a tank vehicle to a stop?
Brake early and apply steady, even pressure the whole way down, rather than braking hard and then releasing the pedal right before the stop. Releasing too soon lets the surging liquid shove the truck forward right as you're trying to settle it.