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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Missouri CDL combination test consists of 20 questions, and you'll need at least 16 correct answers to pass (80%). The test covers the combination vehicles section of the Missouri CDL Manual. Take this practice test now to prepare for the actual MO CDL combination test!
1. In combination vehicles with air brakes, the trailer air supply control should pop out when the air pressure falls within the range of:
100 to 120 psi
10 to 20 psi
20 to 45 psi
2. A trailer jackknife is more likely to happen when the trailer is:
loaded to its full capacity.
empty.
overloaded.
3. Inspecting the fifth-wheel does NOT include:
checking for missing or damaged parts.
backing until the fifth-wheel just touches the trailer.
checking that there are no cracks in the frame.
4. Transporting hanging meat requires special attention. Why?
Because hanging meat can be an unstable load with a high center of gravity.
Because you have to drive fast to get it delivered fresh.
Because refrigerated trucks have less traction.
5. Overloading can have negative effects on:
steering.
braking.
All of the above.
6. When backing a trailer on a curved path you should back towards:
either side.
the driver's side.
neither side (back up straight).
7. The use of brakes on a steep downgrade is:
a supplement to the braking effect of the engine.
the main braking factor.
much more effective than the engine braking effect.
8. On a tractor-trailer equipped with a trailer brake hand valve, the hand valve can be used to:
prevent movement of cargo.
keep from rolling back.
hold compressed air.
9. If the safety relief valve in the air brake system releases air:
the valve is fully operational.
this will supply more power to the brakes.
something is wrong.
10. When driving at night you should:
use your high beams when it is safe and legal to do so.
always use low beams.
All of the above.
 
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MO CDL Combination Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
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