Commercial driver’s license (CDL) knowledge tests · California DMV
Tank Vehicles
Questions and answers
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An “N” endorsement is required for a tank whose individual rated capacity is more than how many gallons?
119 gallons
The tank or tanks must each have a rated capacity of more than 119 gallons.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
For the “N” endorsement to be required, what aggregate rated capacity must the tanks have?
1,000 gallons or more
The tanks together must have an aggregate rated capacity of 1,000 gallons or more.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
Does the liquid or gas have to be a HazMat for the “N” endorsement to be required?
No
The endorsement can be required for liquids or gases that are not hazardous.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
A tank is only temporarily attached to the vehicle or chassis. Can it still make the vehicle a tank vehicle?
Yes, the tank may be permanently or temporarily attached
A tank counts whether it is permanently or temporarily attached.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
A CMV carries an empty storage container tank that is not designed for transportation, rated at 1,000 gallons or more, temporarily attached to a flatbed trailer. Is it a tank vehicle?
No, it is not a tank vehicle
An empty storage tank not designed for transportation, temporarily attached to a flatbed, does not make a tank vehicle.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
A CLP holder has an “N” endorsement. When may this driver operate a tank vehicle?
Only when the tank is empty
A permit holder may not operate a tank vehicle unless it is empty.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
A CLP holder wants to drive an empty tanker that previously contained HazMat. What else is required?
The tank must be purged
An empty tank that held HazMat must also be purged.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
An applicant applies for a Class C CDL with an “N” endorsement only. Is a commercial skills test required?
Yes, in a representative Class C tank vehicle
The applicant must take the skills test in a representative Class C CMV designed to transport liquid or gaseous materials in a tank.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
A driver adds an “N” endorsement to an existing Class C CDL. What is needed?
All applicable knowledge tests, with no commercial skills test
Adding the endorsement to an existing Class C CDL takes the knowledge tests only.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
When should you inspect a tanker?
Before loading, unloading, or driving it
The inspection makes sure the vehicle is safe to carry the liquid or gas and safe to drive.
Section 8 · SECTION 8: TANK VEHICLES ↗ -
Tank vehicles come in many types and sizes. What should you check to know how to inspect yours?
The vehicle’s operator manual
The operator manual tells you how to inspect your particular tank vehicle.
Section 8 · 8.1 – Inspecting Tank Vehicles ↗ -
On all tank vehicles, what is the most important item to check for?
Leaks
Check under and around the vehicle for signs of any leaking.
Section 8 · 8.1.1 – Leaks ↗ -
What does the handbook say about carrying liquids or gases in a leaking tank?
It is a crime, and you will be cited and prevented from driving further
Never carry liquids or gases in a leaking tank.
Section 8 · 8.1.1 – Leaks ↗ -
Besides a citation, what else may you face for a spill from a leaking tank?
You may be liable for the cleanup of the spill
The driver may also be liable for cleaning up any spill.
Section 8 · 8.1.1 – Leaks ↗ -
What do you check on the tank’s body or shell?
Dents or leaks
Look over the body or shell for dents and leaks.
Section 8 · 8.1.1 – Leaks ↗ -
What must be true of the intake, discharge, and cut-off valves before loading, unloading, or moving the vehicle?
They are in the correct position
Check the valves and make sure each is in the correct position.
Section 8 · 8.1.1 – Leaks ↗ -
Where on pipes, connections, and hoses should you look especially carefully for leaks?
Around joints
Leaks are most likely around joints.
Section 8 · 8.1.1 – Leaks ↗ -
What do you check about manhole covers?
That the covers have gaskets and close correctly
Manhole covers need gaskets and must close correctly.
Section 8 · 8.1.1 – Leaks ↗ -
What must you do with the tank vents?
Keep them clear so they work correctly
Vents must be kept clear to work.
Section 8 · 8.1.1 – Leaks ↗ -
Which of these is special purpose equipment you must make sure works, if your tank vehicle has it?
Grounding and bonding cables
The list is vapor recovery kits, grounding and bonding cables, emergency shutoff systems, and a built in fire extinguisher.
Section 8 · 8.1.2 – Check Special Purpose Equipment ↗ -
Which of these is NOT on the handbook’s list of special purpose equipment for tank vehicles?
Converter dolly
A converter dolly is used with double trailers. It is not on the tank equipment list.
Section 8 · 8.1.2 – Check Special Purpose Equipment ↗ -
With what open must you never drive a tank vehicle?
Valves or manhole covers
Never drive a tank vehicle with open valves or manhole covers.
Section 8 · 8.1.2 – Check Special Purpose Equipment ↗ -
What do you do about the emergency equipment required for your tank vehicle?
Find out what you are required to carry and make sure you have it and it works
Know the required emergency equipment, have it, and be sure it works.
Section 8 · 8.1.3 – Special Equipment ↗ -
Why does hauling liquids in tanks require special skills?
Because of the high center of gravity and liquid movement
A high center of gravity and the movement of the liquid make tankers different to drive.
Section 8 · 8.2 – Driving Tank Vehicles ↗ -
What does a high center of gravity mean?
Much of the load’s weight is carried high up off the road
A high center of gravity makes the vehicle top-heavy and easy to roll over.
Section 8 · 8.2.1 – High Center of Gravity ↗ -
What have tests shown about tankers on curves?
They can turn over at the speed limits posted for curves
Liquid tankers are especially easy to roll over, even at posted curve speeds.
Section 8 · 8.2.1 – High Center of Gravity ↗ -
How fast should a tanker take highway curves and on ramp or off ramp curves?
Well below the posted speeds
Take curves and ramps well below the posted speeds.
Section 8 · 8.2.1 – High Center of Gravity ↗ -
What causes liquid surge?
Movement of the liquid in partially filled tanks
Surge comes from liquid moving in a partially filled tank.
Section 8 · 8.2.2 – Danger of Surge ↗ -
What happens when the liquid wave hits the end of the tank?
It tends to push the truck in the direction the wave is moving
When coming to a stop the liquid surges back and forth, and each wave pushes the truck.
Section 8 · 8.2.2 – Danger of Surge ↗ -
You are stopped on ice at an intersection with a partially filled tanker. What can surge do?
The wave can shove the stopped truck out into the intersection
On a slippery surface a surge wave can push a stopped truck into the intersection.
Section 8 · 8.2.2 – Danger of Surge ↗ -
Some liquid tanks are divided into several smaller tanks by bulkheads. What must the driver pay attention to when loading and unloading them?
Weight distribution
Do not put too much weight on the front or rear of the vehicle.
Section 8 · 8.2.3 – Bulkheads ↗ -
When loading the compartments of a tank with bulkheads, what must you avoid?
Putting too much weight on the front or rear of the vehicle
Too much weight at either end is bad weight distribution.
Section 8 · 8.2.3 – Bulkheads ↗ -
What are baffled liquid tanks?
Tanks with bulkheads that have holes to let the liquid flow through
Baffles are bulkheads with holes in them.
Section 8 · 8.2.4 – Baffled Tanks ↗ -
Which surge do baffles help to control?
Forward and backward surge
Baffles help with forward and backward surge.
Section 8 · 8.2.4 – Baffled Tanks ↗ -
What can still occur in a baffled tank and cause a roll over?
Side-to-side surge
Baffles do not stop side-to-side surge.
Section 8 · 8.2.4 – Baffled Tanks ↗ -
What is an unbaffled liquid tanker sometimes called?
A “smooth bore” tank
Unbaffled tanks have nothing inside to slow the flow of the liquid.
Section 8 · 8.2.5 – Unbaffled Tanks ↗ -
How strong is forward-and-back surge in an unbaffled tank?
Very strong
With nothing to slow the liquid, forward-and-back surge is very strong.
Section 8 · 8.2.5 – Unbaffled Tanks ↗ -
What do unbaffled tanks usually transport?
Food products, such as milk
Unbaffled tanks usually carry food products.
Section 8 · 8.2.5 – Unbaffled Tanks ↗ -
Why do sanitation regulations forbid baffles in tanks that carry food products?
Because of the difficulty in cleaning the inside of the tank
Baffles make the inside of the tank hard to clean.
Section 8 · 8.2.5 – Unbaffled Tanks ↗ -
When must you be especially slow and careful with a smooth bore tank?
When starting and stopping
Be extremely cautious with smooth bore tanks, especially when starting and stopping.
Section 8 · 8.2.5 – Unbaffled Tanks ↗ -
What is “outage”?
Room left in a cargo tank for the liquid to expand as it warms
Never load a cargo tank totally full. Liquids expand as they warm and need room.
Section 8 · 8.2.6 – Outage ↗ -
Do all liquids need the same amount of outage?
No, different liquids expand by different amounts and need different outage
You must know the outage requirement when hauling liquids in bulk.
Section 8 · 8.2.6 – Outage ↗ -
Why may you often only partially fill tanks with heavy liquids?
A full tank of dense liquid may exceed legal weight limits
A full tank of dense liquid, such as some acids, can be over the legal weight.
Section 8 · 8.2.7 – How Much to Load? ↗ -
Which of these does NOT determine how much liquid to load into a tank?
The color of the tank
The amount depends on expansion in transit, the weight of the liquid, legal weight limits, and the temperature of the load.
Section 8 · 8.2.7 – How Much to Load? ↗ -
Besides expansion and legal weight limits, what does the amount of liquid to load depend on?
The weight of the liquid and the temperature of the load
Weight and temperature are the other two factors.
Section 8 · 8.2.7 – How Much to Load? ↗ -
The special speeding penalty for tank vehicles applies when transporting more than how much flammable liquid?
500 gallons
The rule covers tank vehicles transporting more than 500 gallons of flammable liquid.
Section 8 · 8.2.8 – Speeding in a Tank Vehicle ↗ -
You speed in a tank vehicle carrying more than 500 gallons of flammable liquid. What is the added penalty for a first offense?
A fine
A first offense brings a fine in addition to any other applicable penalty.
Section 8 · 8.2.8 – Speeding in a Tank Vehicle ↗ -
Within what period does a second speeding offense in such a tank vehicle bring a possible suspension?
Within 2 years of a prior offense
A second or later offense within 2 years of a prior offense can bring a fine, a suspension, or both.
Section 8 · 8.2.8 – Speeding in a Tank Vehicle ↗ -
For a second such offense, how long can the HazMat or cargo “N” endorsement be suspended?
Up to 6 months
The suspension can last up to 6 months.
Section 8 · 8.2.8 – Speeding in a Tank Vehicle ↗ -
What is the maximum driving time within a work period for a driver of a tank vehicle with a capacity greater than 500 gallons when transporting flammable liquid?
10 hours
Drivers of these tank vehicles are limited to 10 hours of driving in a work period.
Section 8 · 8.2.9 – Hours of Service in a Tank Vehicle ↗ -
To which tank vehicle drivers does the 10-hour driving limit apply?
Those driving tank vehicles with a capacity greater than 500 gallons when transporting flammable liquid
The limit is tied to capacity over 500 gallons and a flammable liquid load.
Section 8 · 8.2.9 – Hours of Service in a Tank Vehicle ↗ -
How must you start, slow down, and stop a tank vehicle?
Very smoothly
The high center of gravity and the surge of the liquid call for smooth starts, stops, turns, and lane changes.
Section 8 · 8.3.1 – Drive Smoothly ↗ -
How do you use the brakes to control surge when coming to a stop?
Keep a steady pressure on the brakes and do not release them too soon
Steady brake pressure, held until stopped, helps control surge.
Section 8 · 8.3.2 – Controlling Surge ↗ -
What should you do well before a stop in a tank vehicle?
Brake far in advance and increase your following distance
Brake early and leave more following distance.
Section 8 · 8.3.2 – Controlling Surge ↗ -
You must make a quick stop in a tank vehicle to avoid an accident. Which braking do you use?
Controlled or stab braking
Use controlled or stab braking for a quick stop.
Section 8 · 8.3.2 – Controlling Surge ↗ -
What may happen if you steer quickly while braking in a tank vehicle?
Your vehicle may roll over
Quick steering while braking can roll a tank vehicle.
Section 8 · 8.3.2 – Controlling Surge ↗ -
How should you take a curve in a tank vehicle?
Slow down before the curve, then accelerate slightly through it
The posted speed for a curve may be too fast for a tank vehicle.
Section 8 · 8.3.3 – Curves ↗ -
How do wet roads affect normal stopping distance?
They double it
Wet roads double the normal stopping distance.
Section 8 · 8.3.4 – Stopping Distance ↗ -
How do empty tank vehicles compare with full ones when stopping?
Empty tank vehicles may take longer to stop
An empty tank vehicle may need more distance to stop than a full one.
Section 8 · 8.3.4 – Stopping Distance ↗ -
What may happen if you over steer, over accelerate, or over brake in a tank vehicle?
Your vehicle may skid
Do not over steer, over accelerate, or over brake.
Section 8 · 8.3.5 – Skids ↗ -
On a tank trailer, what may happen if your drive or trailer wheels begin to skid?
Your vehicle may jackknife
A skid of the drive or trailer wheels can lead to a jackknife.
Section 8 · 8.3.5 – Skids ↗ -
When any vehicle starts to skid, what must you do?
Take action to restore traction to the wheels
The response to a skid is to get traction back at the wheels.
Section 8 · 8.3.5 – Skids ↗
Questions and answers by topic
- Licenses, endorsements and tests105
- Disqualifications and state rules110
- Vehicle inspection80
- Basic control and shifting gears47
- Seeing and communicating46
- Controlling your speed62
- Managing space40
- Seeing hazards49
- Distracted and Aggressive Driving71
- Night, Fog, Winter and Hot Weather124
- Railroad Crossings and Mountain Driving65
- Emergencies, ABS and Skids102
- Accident Procedures and Fires49
- Alcohol, Drugs and Illness41
- Hazardous Materials Rules for All Drivers42
- Transporting Cargo Safely79
- Bus Inspection, Loading and Hazardous Materials74
- Driving a Bus: Stops, Crossings and Prohibited Practices56
- Air Brake Parts: Compressor, Tanks and Foundation Brakes52
- Warnings, Spring Brakes, ABS and Dual Systems59
- Inspecting Air Brake Systems61
- Using Air Brakes51
- Driving Combination Vehicles Safely50
- Combination Vehicle Air Brakes and ABS59
- Coupling and Uncoupling63
- Inspecting a Combination Vehicle24
- Pulling Double and Triple Trailers16
- Coupling, Inspecting and Brake Checks for Doubles34
- HazMat basics and who does what48
- Hazard classes, labels and lists64
- Shipping papers and package markings49
- Placards and placard tables40
- Loading and unloading HazMat58
- Bulk packaging and tanks30
- HazMat driving and parking rules72
- HazMat emergencies and reporting60
- Danger zones and mirrors34
- Loading and unloading students47
- Emergency exit and evacuation34
- Railroad-highway crossings40
- Student management, ABS and special situations47