U.S. CDL · TANKER · QUESTIONS & ANSWERS

U.S. CDL Tanker Vehicles Practice — questions and answers

All 30 original Rig Toolbox practice questions for this test, printed in full with the correct answer and an explanation for each one. Read them here, then put them to work in Practice or the Exam Simulator — no sign-up, ever.

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Independent practice: these are Rig Toolbox's own study questions, not official exam questions. Always confirm rules in the official handbook for the licence you are taking.

About this question set

How many questions are here? 30 — the full bank for this test. The interactive test draws 20 of them at a time.

What is this test? Original liquid-tank practice covering surge, loading and safe tanker driving, based on the tanker section of state CDL manuals.

Every question, with its answer

Question 1

The tank vehicle (N) endorsement is required for hauling liquid or gas in tanks that meet which size rule?

Only tanks over 10,000 gallons
Any single bottle over 5 gallons
Individual tanks rated over 119 gallons with a combined rated capacity of 1,000 gallons or more
Only gasoline tanks

Correct answer: Individual tanks rated over 119 gallons with a combined rated capacity of 1,000 gallons or more

That size definition covers permanently mounted and temporarily attached bulk tanks alike.

Question 2

What is liquid surge?

A pressure relief valve opening
Liquid moving back and forth, and side to side, inside a partly filled tank as the vehicle speeds up, slows or turns
A leak at the manhole
Fuel starvation of the engine

Correct answer: Liquid moving back and forth, and side to side, inside a partly filled tank as the vehicle speeds up, slows or turns

Surge is the wave motion of the load itself, and it can push against the direction you are trying to control.

Question 3

What do bulkheads do in a liquid tank?

Add weight for traction
Make the tank one large space
Divide the tank into smaller separate compartments, which greatly reduces surge
Vent vapour to the air

Correct answer: Divide the tank into smaller separate compartments, which greatly reduces surge

Several smaller compartments keep the moving mass in each section small.

Question 4

What do baffles do in a tank?

Block liquid from moving side to side completely
Slow the front-to-back movement of liquid, but do not stop side-to-side surge
Increase the tank capacity
Filter the cargo

Correct answer: Slow the front-to-back movement of liquid, but do not stop side-to-side surge

Baffles are perforated walls that calm the forward wave; sideways slosh in a turn is still fully present.

Question 5

Which tank type produces the strongest surge?

A fully baffled chemical tank
A smoothbore (unbaffled) tank, such as many food-grade tankers
An empty dry van
A tank with bulkheads

Correct answer: A smoothbore (unbaffled) tank, such as many food-grade tankers

With nothing inside to break up the wave, a smoothbore load moves with full force.

Question 6

Why are milk and many food tankers smoothbore inside?

It makes the tank cheaper to insure
Baffles are illegal
Milk does not surge
Sanitation rules require smooth interiors that can be cleaned completely

Correct answer: Sanitation rules require smooth interiors that can be cleaned completely

Health rules demand a fully cleanable interior, so drivers of these tankers must manage the strongest surge of all.

Question 7

Which fill level usually gives the worst surge?

Completely empty
About half full
Completely full
One quarter full in a baffled tank

Correct answer: About half full

A partial load has room to build a wave; a pressed-full tank has almost no free surface to move.

Question 8

What can liquid surge do when you brake to a stop at an intersection?

It locks the rear brakes
The wave striking the front of the tank can shove the vehicle forward, even into the intersection
Nothing noticeable
It always shortens the stop

Correct answer: The wave striking the front of the tank can shove the vehicle forward, even into the intersection

Keep stopping early and hold firm brake pressure after stopping so the surge cannot roll you ahead.

Question 9

What is “outage” when loading a tank?

A type of valve
The time the tank is out of service
A power failure at the rack
The empty space left for the liquid to expand as it warms

Correct answer: The empty space left for the liquid to expand as it warms

Liquids expand with temperature; a tank filled completely full when cold can overflow or rupture when warm.

Question 10

Why do tank vehicles roll over on curves that other trucks handle easily?

Their tires are smaller
Their high centre of gravity lets them roll at speeds near or even below the posted curve speed
Their brakes are weaker
They have more axles

Correct answer: Their high centre of gravity lets them roll at speeds near or even below the posted curve speed

A tall, heavy liquid load sits high; take ramps and curves well below the posted speed.

Question 11

How can an EMPTY tank vehicle compare with a loaded one for stopping distance?

They are identical
It always stops shorter
It may take longer to stop because light weight means less tire traction
Empty tanks cannot be driven

Correct answer: It may take longer to stop because light weight means less tire traction

Like empty trailers, light tankers have less grip and strong brakes, so stops can be longer, not shorter.

Question 12

Why must tanker drivers start, stop and change speed especially smoothly?

To keep the paint from cracking
It is only a comfort issue
To save fuel only
Sudden changes build larger surge waves that can push the vehicle out of control

Correct answer: Sudden changes build larger surge waves that can push the vehicle out of control

Gentle control keeps the liquid calm; abrupt inputs are amplified by the moving load.

Question 13

Before a trip, what should you know about the tank’s emergency shut-off system?

Only its colour
Where the remote shut-off is and that it works, so flow can be stopped fast in a leak or fire
Nothing; it is the loader’s concern
That it is used for parking

Correct answer: Where the remote shut-off is and that it works, so flow can be stopped fast in a leak or fire

Knowing and testing the shut-off (often at the front of the tank or near the discharge area) is part of tanker pre-trip.

Question 14

Before driving a loaded tank, manholes and covers must be:

Left slightly open to vent
Closed and latched securely
Removed
Covered with tape

Correct answer: Closed and latched securely

An unlatched manhole can spill the load in surge or a rollover and fails the pre-trip inspection.

Question 15

You find a tank leaking while driving. You should:

Keep driving to the destination quickly
Speed up so the leak blows dry
Open the manhole to check
Stop in the safest available place and get help; move the vehicle only as emergency officials direct

Correct answer: Stop in the safest available place and get help; move the vehicle only as emergency officials direct

A leaking tank is an emergency scene, not a delivery problem; distance and expert help come first.

Question 16

Why can a tank reach its legal weight limit while still looking partly empty?

Dense liquids weigh more per gallon, so weight limits can be reached before the tank is full
The gauges always lie
Air pockets add weight
It cannot happen

Correct answer: Dense liquids weigh more per gallon, so weight limits can be reached before the tank is full

With heavy products you must check the gross weight, not just the fill level.

Question 17

During loading or unloading of a hazmat tank, the driver must:

Stay with the vehicle, keep it attended, and chock wheels as required
Open every valve at once
Disconnect all the lights
Leave the area

Correct answer: Stay with the vehicle, keep it attended, and chock wheels as required

The driver remains present and in control throughout transfer operations.

Question 18

Why should you check the inspection and test dates marked on a cargo tank before loading?

For the insurance discount
It sets the speed limit
An overdue tank must not be loaded; periodic pressure and visual tests keep the tank legal and safe
The dates are decorative

Correct answer: An overdue tank must not be loaded; periodic pressure and visual tests keep the tank legal and safe

Cargo tanks carry required retest dates; loading an expired tank is a violation and a risk.

Question 19

The safest way to take a curve in a tanker is to:

Brake firmly all the way through the curve
Let the surge settle the tank
Accelerate through the curve
Slow to a safe speed before the curve and avoid braking or sharp steering while in it

Correct answer: Slow to a safe speed before the curve and avoid braking or sharp steering while in it

Entering slowly keeps both the centre of gravity and the liquid wave under control.

Question 20

Following distance in a tanker should be:

The same as a car
Reduced so others cannot cut in
Set by the length of the tank only
Increased, because stopping distances are longer and surge adds a push

Correct answer: Increased, because stopping distances are longer and surge adds a push

Extra space absorbs the tanker’s longer stops and the forward push of the load.

Question 21

Why don’t baffles protect you in a quick lane change?

They make side surge worse by design
Baffles slow front-to-back motion; side-to-side surge still strikes the side of the tank in turns and lane changes
Baffles dissolve in fuel
Baffles only work when parked

Correct answer: Baffles slow front-to-back motion; side-to-side surge still strikes the side of the tank in turns and lane changes

Lateral surge is controlled only by slow, smooth steering.

Question 22

Before loading flammable liquid, why are bonding and grounding cables connected?

To test the lights
To hold the tank still
To charge the battery
To prevent a static-electricity spark that could ignite vapours

Correct answer: To prevent a static-electricity spark that could ignite vapours

Flowing fuel builds static charge; bonding equalises it and grounding drains it safely away.

Question 23

When you accelerate hard in a partly filled tanker, the liquid first:

Moves only upward
Stays perfectly still
Slams to the rear, then surges forward again as you steady speed
Rushes to the front

Correct answer: Slams to the rear, then surges forward again as you steady speed

Each speed change starts a new wave; smooth throttle keeps the wave small.

Question 24

On a downgrade, what extra problem does a tanker face?

The tank empties uphill
The load freezes
Gravity does not affect liquid
Surge adds a forward push each time you brake, and a lower gear chosen at the top protects the brakes

Correct answer: Surge adds a forward push each time you brake, and a lower gear chosen at the top protects the brakes

Plan the descent like any heavy vehicle, expecting the load to push as brakes are applied.

Question 25

If a tanker’s drive wheels begin to skid on a wet road, you should:

Ease off the brake or throttle to let the wheels roll and regain grip, steering gently
Turn the wheel sharply
Apply the parking brake
Accelerate out of it

Correct answer: Ease off the brake or throttle to let the wheels roll and regain grip, steering gently

Rolling wheels grip; locked or spinning wheels slide, and the high load makes recovery harder.

Question 26

Which railroad-crossing rule applies to a placarded cargo tank vehicle?

It may cross without stopping if the driver looks
It should stop on the tracks to check
It never needs to stop
It must stop at the crossing, check both directions, then cross without shifting on the tracks

Correct answer: It must stop at the crossing, check both directions, then cross without shifting on the tracks

Placarded tank vehicles are in the always-stop group at railroad grade crossings.

Question 27

During the pre-trip of a tanker, valves, piping and fittings should be checked for:

Extra product from the last load
Matching paint
Leaks, damage and secure caps, with discharge valves correctly set
Being as loose as possible

Correct answer: Leaks, damage and secure caps, with discharge valves correctly set

A leaking valve or wrong-set manifold becomes a spill on the road.

Question 28

Compartments carrying different products must be loaded so that:

Any valve setting is fine
The correct valves and manifolds are set for each product and nothing is cross-connected
All products are mixed to save time
Only the front compartment is used

Correct answer: The correct valves and manifolds are set for each product and nothing is cross-connected

Wrong valve settings can contaminate products or discharge the wrong liquid.

Question 29

What is the best defence against surge when approaching a red light?

Brake late and firmly
Pump the brakes repeatedly
Begin braking early and gently, and keep pressure on the brakes once stopped
Let the vehicle roll freely

Correct answer: Begin braking early and gently, and keep pressure on the brakes once stopped

Early, gentle braking keeps the wave small and holding the brake counters the final forward push.

Question 30

Posted advisory speeds on exit ramps are set for cars. In a tanker you should:

Add 5 mph for your size
Ignore them entirely
Use them as a minimum
Treat them as too fast for a high-centre-of-gravity tank and go slower

Correct answer: Treat them as too fast for a high-centre-of-gravity tank and go slower

Many tanker rollovers happen on ramps taken at or near the posted advisory speed.

Ready to try them for real?