CCDL Permit Prep

Combination Vehicles · page 3 of 3

Combination Vehicles questions 41–58

Part of the 58-question Combination Vehicles pool. Each answer cites the FMCSA CDL Manual or the federal rule it comes from.

Practise these as a timed set

  1. How should the landing gear crank be stowed?

    • ACarried inside the cab only
    • BLeft hanging free
    • CPlaced on the fifth wheel
    • DSecured in its holderCorrect

    FMCSA Section 6.4.1 says to raise the landing gear fully and secure the crank handle safely. Section 11.4.2 says the crank handle must be in place and secured.

    FMCSA Commercial Driver License Manual · Section 6.4.1: Coupling Tractor-Semitrailers, Step 15; Section 11.4.2: Side of Trailer (Landing Gear) · verified 2026-09-08

  2. Why does a combination vehicle need a wider turn at a corner?

    • AThe tractor loses power turning
    • BThe trailer cuts inside the tractor's pathCorrect
    • CThe trailer brakes drag in turns
    • DThe mirrors fold on tight corners

    FMCSA Section 6.1.6 explains that trailer rear wheels off-track more than the tractor. Steer wide enough around a corner so the rear end does not run over the curb or pedestrians.

    FMCSA Commercial Driver License Manual · Section 6.1.6: Turn Wide · verified 2026-09-08

  3. What should you do before pulling the fifth wheel release handle?

    • ARaise the landing gear fully
    • BRelease the trailer brakes
    • CSecure the trailer and lower the gearCorrect
    • DDisconnect the air lines only

    Secure the trailer against movement, lower the landing gear onto suitable ground, and disconnect and stow lines before unlocking as prescribed. A raised support or disconnected hoses alone cannot keep the trailer stable.

    Oregon DMV Commercial Driver Manual · 6.2.4 Air-lines; 6.2.5 Hose Couplers; 6.4.1 Coupling; 6.4.2 Uncoupling · verified 2026-09-07

  4. If your tractor has a sliding fifth wheel, what must you make sure of when inspecting it?

    • AThat it is lockedCorrect
    • BThat it is fully forward
    • CThat it is unlatched
    • DThat it is greased less than a fixed one

    The coupling inspection says that with a sliding fifth wheel you must make sure it is locked.

    FMCSA Commercial Driver's License Manual (July 2014) · Section 6 Coupling, Step 1 Inspect Fifth Wheel · verified 2026-09-25

  5. What should you check on the trailer's suspension?

    • ASprings, hangers and air suspension are not damaged or leakingCorrect
    • BThat it is freshly washed
    • CThat the axles are removable
    • DThat it sits perfectly level

    FMCSA Section 11.2.2 says to check suspension components for damage, secure mounting, and leaks, including spring hangers and air-ride suspension. Perform the same inspection on each axle, including the trailer when equipped.

    FMCSA Commercial Driver License Manual · Section 11.2.2: Suspension · verified 2026-09-08

  6. Why is the gap between tractor and trailer important?

    • AIt changes the fuel economy only
    • BToo little causes contact when turningCorrect
    • CIt sets the trailer's brake timing
    • DIt determines the lighting circuit

    A fifth wheel too far forward can let the trailer contact the cab or the tractor frame contact the landing gear during turns. Check the actual turning clearances after adjustment; the gap is not only an aerodynamic issue.

    Oregon DMV Commercial Driver Manual · 6.5.1 Combination walk-around inspection; 6.5.2 brake checks · verified 2026-09-07

  7. What should you do if the trailer brakes do not work during the pre-drive test?

    • AUse the tractor brakes only
    • BDrive gently to the destination
    • CHave the brake problem fixed before drivingCorrect
    • DIncrease the following distance

    FMCSA Section 6.2.5 says to test the trailer brakes before driving and make sure they work. Do not drive the combination until a brake problem is fixed.

    FMCSA Commercial Driver License Manual · Section 6.2.5: Hose Couplers (Glad Hands) · verified 2026-09-08

  8. How should trailer air lines be positioned?

    • ASupported, free from damage, with enough slack for turnsCorrect
    • BLeft loose so they can drag behind the trailer
    • CPulled tight across moving parts
    • DConnected without checking their routing

    FMCSA Sections 6.4.1 and 6.5.1 say air lines must be safely supported away from crushing or catching, free from damage, and secured with enough slack for turns.

    FMCSA Commercial Driver License Manual · Section 6.4.1: Coupling Tractor-Semitrailers, Steps 7 and 14; Section 6.5.1: Inspecting Combination Vehicles · verified 2026-09-08

  9. How does an empty heavy vehicle generally stop compared with a loaded one?

    • AIt may require a greater stopping distance because it has less tractionCorrect
    • BIt always stops in a shorter distance
    • CIt has more traction because it weighs less
    • DIt does not need the normal brake checks

    FMCSA Section 2.6.1 says empty trucks require greater stopping distances because an empty vehicle has less traction. The rule is about available traction and stopping distance, not a guaranteed wheel-lock event.

    FMCSA Commercial Driver License Manual · Section 2.6.1: Speed and Stopping Distance · verified 2026-09-08

  10. Why may a combination vehicle need a larger gap to enter traffic than a car?

    • AIts size and slower acceleration require more spaceCorrect
    • BIts mirrors show less behind
    • CIts engine has less torque than every car
    • DIts brakes release more slowly

    FMCSA Section 2.7.7 says large vehicles may need a much larger gap to enter traffic because of their slow acceleration and the space they require.

    FMCSA Commercial Driver License Manual · Section 2.7.7: Space Needed to Cross or Enter Traffic · verified 2026-09-08

  11. What should you do if the trailer begins to swing on a wet road?

    • AApply the parking brake
    • BBrake hard immediately
    • CAccelerate through the skid
    • DRelease the brakes to regain tractionCorrect

    FMCSA Section 6.1.5 says to stop using the brake and release the brakes to regain traction when a trailer skid begins. Do not use the trailer hand brake to straighten the rig.

    FMCSA Commercial Driver License Manual · Section 6.1.5: Prevent Trailer Skids · verified 2026-09-08

  12. What width must States generally allow for commercial motor vehicles on the National Network, outside stated exceptions?

    • A84 inches
    • B102 inchesCorrect
    • C120 inches
    • D144 inches

    Federal law generally requires States, other than Hawaii, to allow commercial motor vehicles up to 102 inches wide on the specified National Network highways, subject to statutory exceptions. The calculation excludes qualifying safety and energy-conservation devices. State permits and route rules govern operations outside that scope.

    United States Code — 49 U.S.C. 31113, Width limitations · 31113(a)–(c) — National Network width limitation and permits · verified 2026-09-07

  13. Why should a driver back toward the driver's side whenever possible?

    • AThe trailer turns more sharply that way
    • BThe driver can watch the trailer directlyCorrect
    • CIt needs less room at the dock
    • DThe mirrors need no adjustment

    FMCSA Section 2.2.4 says backing toward the driver's side lets the driver see better and watch the rear through the side window; backing toward the right is more dangerous.

    FMCSA Commercial Driver's License Manual · Section 2.2.4: Backing Safely · verified 2026-09-08

  14. What should a driver check along the path before backing?

    • AOnly the width of the trailer
    • BOnly the number painted on the door
    • COnly whether the door is already open
    • DSide and overhead clearance and other hazards in the pathCorrect

    FMCSA Section 2.2.4 says to look at the line of travel before backing and check side and overhead clearance and hazards in or near the path.

    FMCSA Commercial Driver's License Manual · Section 2.2.4: Backing Safely · verified 2026-09-08

  15. How should a driver correct drift during a straight-line back?

    • ATurn the top of the steering wheel in the direction of the driftCorrect
    • BWith one large input near the end
    • CBy stopping and re-coupling the trailer
    • DBy speeding up to straighten the trailer

    FMCSA Section 6.1.7 says to correct trailer drift immediately by turning the top of the steering wheel in the direction of the drift.

    FMCSA Commercial Driver's License Manual · Section 6.1.7: Backing with a Trailer · verified 2026-09-08

  16. What is a pull-up during a backing maneuver?

    • AApplying the trailer brakes only
    • BDriving forward to reset the trailer angleCorrect
    • CRaising the landing gear part way
    • DSetting the fifth wheel to the rear

    FMCSA Section 6.1.7 says to make pull-ups when backing a trailer to reposition the vehicle as needed.

    FMCSA Commercial Driver's License Manual · Section 6.1.7: Backing with a Trailer · verified 2026-09-08

  17. How fast should a combination vehicle be moving while backing?

    • AFast enough to keep the trailer straight
    • BAt normal yard driving speed
    • CAs slowly as possible, using the lowest reverse gearCorrect
    • DAs fast as the spotter walks ahead

    FMCSA Section 2.2.4 says to back as slowly as possible and use the lowest reverse gear so steering errors can be corrected and the vehicle can stop quickly.

    FMCSA Commercial Driver's License Manual · Section 2.2.4: Backing Safely · verified 2026-09-08

  18. How often should both mirrors be checked while backing?

    • AOnly when the spotter signals
    • BOnce at the start of the maneuver
    • COnly the driver's side throughout
    • DFrequently, checking both outside mirrorsCorrect

    FMCSA Section 2.2.4 says to check the outside mirrors on both sides frequently and get out to check the path if unsure.

    FMCSA Commercial Driver's License Manual · Section 2.2.4: Backing Safely · verified 2026-09-08