Tank Vehicles practice test

Tank Vehicles questions with answers

Every question below carries the answer, the reason, and the section of the FMCSA CDL Manual or 49 CFR it comes from. Nothing here is a recalled exam question.

1. What liquid movement do baffles help control in a tank vehicle?

   • AOnly fuel consumption
   • BSide-to-side surge
   • CBoth front-to-back and side-to-side surge
   • DForward-and-backward surgeCorrect

   Baffles are bulkheads with openings that let liquid flow through. They help control forward-and-backward surge, but side-to-side surge can still occur and contribute to rollover.

   Oregon Commercial Driver Manual · Section 8.2.4: Baffled Tanks · verified 2026-09-07

2. A Class B truck carries liquid in four temporarily attached cargo tanks, each rated at 250 gallons. Does this meet the federal tank-vehicle capacity definition?

   • ANo, because each tank is under 1,000 gallons
   • BNo, because only permanent tanks count
   • CNo, because the liquid is not hazardous
   • DYes: each tank exceeds 119 gallons and the total rated capacity is 1,000 gallonsCorrect

   The four rated capacities total 1,000 gallons, and each exceeds 119 gallons. Temporary attachment counts. The rule uses rated capacity, not just the amount loaded; non-hazardous liquid can also require N.

   eCFR 49 CFR 383.5 and Oregon CDL manual section 8 · 383.5 tank vehicle definition · verified 2026-09-07

3. When approaching an ordinary stop in a tank vehicle, which method helps control surge?

   • ABrake far in advance and keep steady pressure through the stopCorrect
   • BBrake hard and quickly
   • CBrake only at the last moment
   • DUse only the parking brake

   Brake far in advance and increase following distance. Keep steady brake pressure through the stop; do not release too soon, because liquid surge can push a stopped truck on a slippery surface.

   Oregon Commercial Driver Manual · Section 8.3.2: Controlling Surge · verified 2026-09-07

4. A tanker is carrying a partial liquid load. Why should the driver use smooth speed changes?

   • AA partial load is always too light to stop
   • BLiquid has room to surge and affect controlCorrect
   • CThe engine must always work harder
   • DTire wear alone determines the risk

   Surge can affect a partly loaded tank. A partial load is not automatically safer or more dangerous in every respect; use the correct loading plan and manage liquid movement.

   Oregon DMV Commercial Driver Manual · 8.2.2; 8.2.6–8.2.7; 8.3.1 · verified 2026-09-07

5. What is the purpose of solid bulkheads inside a liquid cargo tank?

   • ATo divide the tank only into an upper and lower half
   • BTo let liquid pass through openings like baffles
   • CTo form separate compartments whose loading must keep weight balancedCorrect
   • DTo replace required tank venting

   Solid bulkheads form compartments. Check weight distribution when loading or unloading them; do not overload the front or rear. Equipment details depend on the tank design.

   Oregon DMV Commercial Driver Manual · 8.2.3–8.2.4 · verified 2026-09-07

6. Why does liquid surge make a partly loaded tank vehicle harder to control?

   • ALiquid movement can push the vehicle in the direction its wave travelsCorrect
   • BIt affects fuel efficiency, not vehicle control
   • CIt causes extra tire wear but does not affect braking or turning
   • DIt matters when the tank is completely full, not when partially full

   Liquid surge is movement in a partially filled tank. As the vehicle changes speed, the liquid moves back and forth; when the wave reaches a tank end, it tends to push the truck in the wave's direction.

   Oregon Commercial Driver Manual · Section 8.2.2: Danger of Surge · verified 2026-09-07

7. When driving a tanker through an on-ramp or off-ramp curve, you should:

   • ATake the posted ramp speed exactly
   • BSpeed up to clear the ramp before the curve tightens
   • CSlow to well below the posted ramp speed because of the high rollover riskCorrect
   • DBrake hard midway through the curve

   Slow before the ramp curve. The posted speed may be too fast for a tanker; choose a lower safe speed for its load and conditions and steer smoothly.

   Oregon DMV Commercial Driver Manual · 8.2.1; 8.3.3 · verified 2026-09-07

8. Why does a smooth-bore liquid tank require particular care when starting or stopping?

   • AIts walls necessarily corrode faster than other tanks
   • BEvery smooth-bore tank has thinner walls
   • CIt lacks baffles to limit forward-and-back liquid surgeCorrect
   • DIt can carry only one legally permitted food product

   Without baffles, liquid can surge strongly as speed changes. Use smooth starts and stops; the absence of baffles does not establish wall thickness or a universal cargo restriction.

   Oregon DMV Commercial Driver Manual · 8.2.5; 8.3.1 · verified 2026-09-07

9. A loading plan specifies outage for a liquid cargo. Why must the driver use the requirement for that product?

   • AAll liquids expand by exactly the same amount
   • BDifferent liquids need different space for expansionCorrect
   • COutage depends only on the paint color of the tank
   • DMore liquid weight always means less outage is needed

   Outage is space for expansion. Do not use a guessed ranking of products to set the fill level; use the product-specific requirement and observe weight limits.

   Oregon DMV Commercial Driver Manual · 8.2.6–8.2.7 · verified 2026-09-07

10. Before loading, unloading, or driving a tank vehicle, how should its fitted emergency shut-off equipment be checked?

    • AIgnore it until the next annual inspection
    • BCheck only after a leak develops
    • COperate it using any procedure used on a different tanker
    • DFollow this vehicle’s inspection procedure and make sure it worksCorrect

    Inspect the tank vehicle before these operations and follow its operator manual. Required periodic inspections do not replace the driver’s equipment checks.

    Oregon DMV Commercial Driver Manual · 8.1–8.1.2 · verified 2026-09-07

11. A partly loaded liquid tanker must slow for a curve ahead. What load movement must the driver allow for?

    • AThe liquid becomes fixed in place as soon as braking starts
    • BLiquid can surge forward and back as speed changesCorrect
    • CTank pressure alone determines steering response
    • DThe liquid disappears from the front compartment

    Brake smoothly before the curve and allow space for surge. Do not assume a particular steering-wheel feel will warn you before the load affects control.

    Oregon DMV Commercial Driver Manual · 8.2.2; 8.3.1–8.3.3 · verified 2026-09-07

12. Why does a partly filled liquid tank need special care during speed changes?

    • AThe load always weighs more than a full tank
    • BA lower center of gravity causes tire wear
    • CLiquid has room to move and affect vehicle controlCorrect
    • DOnly fuel economy is affected

    Free liquid movement can push the vehicle as speed changes. There is no universal safest fill level: expansion space, weight limits, tank design, and handling all matter.

    Oregon DMV Commercial Driver Manual · 8.2.2; 8.2.6–8.2.7 · verified 2026-09-07

13. For a DOT MC 331 cargo tank, the specification plate includes:

    • ACargo-tank and vehicle manufacturer information, dates, and maximum payloadCorrect
    • BThe driver's certification number and endorsement class
    • CThe carrier's USDOT number only
    • DThe date of the last oil change

    For a DOT MC 331 cargo tank, the specification plate includes cargo-tank motor vehicle and cargo-tank manufacturer information, certification and manufacture dates, and maximum payload. It can also list lining, heating-system, and serial information when applicable.

    eCFR 49 CFR § 178.337-17(c) · Section 178.337-17(c): Specification plate · verified 2026-09-08

14. A liquid tanker has conventional baffles with openings. Which hazard still needs care in a curve?

    • AThe baffles eliminate every kind of surge
    • BBaffles make the posted curve speed safe for every load
    • CSide-to-side liquid movement can still contribute to rolloverCorrect
    • DBaffles remove the need for expansion space

    Conventional baffles limit forward-and-back surge. They do not make the tank immune to side-to-side movement or rollover.

    Oregon DMV Commercial Driver Manual · 8.2.1; 8.2.4 · verified 2026-09-07

15. A loader suggests filling every bit of a liquid tank to prevent surge. What should the driver do?

    • AReject the plan and leave the required outageCorrect
    • BAccept because a completely full tank is always safer
    • CAccept if the tank has baffles
    • DAccept if the journey is short

    Do not remove required expansion space to reduce surge. A lawful loading plan must allow for the product’s expansion and weight limits, while the driver still manages surge.

    Oregon DMV Commercial Driver Manual · 8.2.6–8.2.7 · verified 2026-09-07

16. A cargo tank used to transport hazardous material is now empty. No federal crossing exception applies. Why must it still make the required stop?

    • ASection 392.10 includes such cargo tanks whether loaded or emptyCorrect
    • BEvery freight truck must stop at every crossing
    • CAn empty tank can never contain a hazard
    • DOnly buses have a federal stopping duty

    The specified cargo-tank category is covered whether loaded or empty. Do not decide solely from the current load or presence of a placard; identify the vehicle category and applicable exceptions.

    49 CFR § 392.10 · 392.10(a) listed vehicles and (b) exceptions · verified 2026-09-07

17. Why should a loaded liquid tanker enter a curve well below its posted speed?

    • APosted speeds never apply to commercial vehicles
    • BTank brakes always fail in curves
    • CIts high center of gravity and liquid movement increase rollover riskCorrect
    • DLiquid cargo always removes tire grip

    A posted curve speed can be too fast for a tank vehicle. Reduce speed before the curve; a posted number does not guarantee stability for this vehicle and load.

    Oregon DMV Commercial Driver Manual · 8.2.1; 8.3.3 · verified 2026-09-07

18. How should you brake a partly loaded tanker approaching a stop?

    • AWith the trailer brakes only
    • BLate and firmly to settle the load
    • CIn short bursts to break up surge
    • DEarly and smoothly, with extra room and steady pressure through the stopCorrect

    Brake far in advance and increase following distance. Keep steady pressure on the brakes through the stop and do not release too soon, because surge can still push a stopped truck on a slippery surface.

    Oregon Commercial Driver Manual · Section 8.3.1–8.3.2: Drive Smoothly; Controlling Surge · verified 2026-09-07

19. A cargo tank used to transport gasoline reaches a rail grade crossing with no applicable federal exception. What must its driver do?

    • AStop before crossing the tracksCorrect
    • BCross without slowing if clear
    • CSound the horn and continue
    • DShift down while on the tracks

    This hazardous-material cargo tank falls within the listed stopping categories. Stop, look and listen, then cross in a gear that permits completion without shifting. Tank shape alone does not define every vehicle stopping rule.

    49 CFR § 392.10 · 392.10(a) listed vehicles and (b) exceptions · verified 2026-09-07

20. A partly loaded tanker is approaching a signal on a slippery road. How can the driver reduce the risk of surge pushing it past the stop point?

    • AAccelerate toward the signal to settle the liquid
    • BBrake early and smoothly, leave extra space, and keep steady brake pressure through the stopCorrect
    • CUse only the parking brake while moving
    • DSelect a higher gear to stop the liquid moving

    Plan the stop before reaching the intersection. Surge can push even a stopped tanker on a slippery surface, so avoid releasing the brakes too soon.

    Oregon DMV Commercial Driver Manual · 8.2.2; 8.3.2 · verified 2026-09-07