Tank Vehicles
Liquid loads move
A partly filled tank lets liquid surge forward, backward, and sideways. That surge changes stopping distance and can tip a rig over.
Concepts to master
- Surge and slosh: Liquid moves opposite to acceleration and braking, pushing the vehicle. A full tank moves less; a partly filled tank moves most.
- Baffles: Dividers inside the tank slow the movement of liquid but do not eliminate it.
- High center of gravity: Tankers roll over more easily, especially in curves and on ramps.
- Smooth driving: Brake and accelerate gently; make steady steering inputs.
- Curves: Enter slowly. Surge can push you off the road or into another lane.
- Special cargo: Some tanks carry flammable or corrosive materials requiring placards.
Traps
A frequent question: does a full tank surge more than a partly filled one? No - a partly filled tank surges most. Another trap: baffles reduce but do not stop surge, so you still slow down.
Worked example
You are hauling a partly filled milk tank and approach a curve posted 35 mph. Because the liquid will shift outward as you turn, you slow to 25 mph before the curve and accelerate gently only after the tank is straight again.
Rule of thumb
Treat every tanker as a high-center-of-gravity vehicle: slow before curves, brake early, and never make sudden moves.