CDL · Driving Tank Vehicles

What is the most dangerous handling characteristic of a tank vehicle?

Correct answer

High center of gravity combined with liquid surge inside the tank

  1. A High fuel consumption
  2. B High center of gravity combined with liquid surge inside the tank
  3. C Slow acceleration
  4. D Difficulty reversing

Why this is the answer

Tank vehicles have a high center of gravity (the tank itself sits high above the chassis and the liquid further raises the center) and the liquid inside shifts during acceleration, braking, and turning. The combination is exceptionally prone to rollovers. Drivers must reduce speed dramatically in curves (often 5-15 mph below posted curve advisories), slow before turns rather than during, accelerate gently from stops, and avoid sudden steering. Tanker rollovers happen routinely on highway exit ramps where drivers underestimate the curve. Liquid surge can also push the vehicle through a stop sign even after the driver hits the brakes. The defensive principle: slow down, smooth inputs, expect the unexpected from the cargo.
Source: FMCSA CDL Manual 8.2.1 High Center of Gravity

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