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Iowa CDL Combination Vehicles Test Practice Questions - Iowa Commercial Driver License Combination Vehicles Test Exam
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Question
1
of 25
QUESTION 1 / 25
Iowa DOT lists the Class A Combination Vehicle knowledge test as how many questions?
Choose one answer below.
A
50
✓
B
20
✓
C
10
✓
D
25
✓
QUESTION 2 / 25
How many questions may be missed on Iowa DOT's 20-question Combination Vehicle test?
Choose one answer below.
A
5
✓
B
10
✓
C
4
✓
D
2
✓
QUESTION 3 / 25
What is the FMCSA minimum passing score for CDL knowledge tests?
Choose one answer below.
A
60%
✓
B
70%
✓
C
90%
✓
D
80%
✓
QUESTION 4 / 25
The Combination Vehicle test is mainly for applicants seeking which CDL class?
Choose one answer below.
A
Class A
✓
B
Class B only
✓
C
Class C only
✓
D
Motorcycle endorsement
✓
QUESTION 5 / 25
For a federal Class A combination, the towed unit is generally over what threshold?
Choose one answer below.
A
26,001 pounds
✓
B
10,000 pounds
✓
C
5,000 pounds
✓
D
8,000 pounds
✓
QUESTION 6 / 25
Which vehicle is a combination vehicle?
Choose one answer below.
A
A passenger car
✓
B
A single dump truck with no trailer
✓
C
A tractor pulling a semitrailer
✓
D
A straight box truck with no trailer
✓
QUESTION 7 / 25
Why do combination vehicles require more skill than single CMVs?
Choose one answer below.
A
They are always shorter
✓
B
They do not use mirrors
✓
C
They have no cargo
✓
D
They are usually longer, heavier, and harder to maneuver
✓
QUESTION 8 / 25
What cargo condition raises rollover risk?
Choose one answer below.
A
Cargo loaded high or off-center
✓
B
Cargo kept low and centered
✓
C
Speed reduced before ramps
✓
D
Smooth steering
✓
QUESTION 9 / 25
What driver action causes many combination-vehicle rollovers?
Choose one answer below.
A
Keeping space ahead
✓
B
Turning too fast
✓
C
Checking mirrors
✓
D
Backing slowly
✓
QUESTION 10 / 25
What does the crack-the-whip effect involve?
Choose one answer below.
A
Normal air-tank draining
✓
B
Landing gear cranking
✓
C
Quick steering amplified toward the rear trailer
✓
D
Fifth wheel lubrication
✓
QUESTION 11 / 25
Above 40 mph, what is added to the 1-second-per-10-feet following-distance rule?
Choose one answer below.
A
No extra time
✓
B
Five extra seconds per trailer
✓
C
A fixed two-second rule
✓
D
One extra second
✓
QUESTION 12 / 25
Why can an empty trailer lock its wheels more easily?
Choose one answer below.
A
Less weight on the tires gives poorer traction
✓
B
The brakes are removed
✓
C
The tanks are empty by design
✓
D
The fifth wheel unlocks
✓
QUESTION 13 / 25
What is the earliest and best way to notice a trailer skid?
Choose one answer below.
A
Listen to the landing gear
✓
B
Watch the trailer in the mirrors
✓
C
Wait for a horn
✓
D
Check the fuel gauge
✓
QUESTION 14 / 25
If trailer wheels lock and the trailer swings, what should you do?
Choose one answer below.
A
Set parking brakes
✓
B
Accelerate sharply
✓
C
Release the brakes to regain traction
✓
D
Apply the hand valve harder
✓
QUESTION 15 / 25
What is off-tracking?
Choose one answer below.
A
An ABS lamp
✓
B
A fifth wheel slide adjustment
✓
C
A glad-hand leak
✓
D
Rear wheels following a shorter path than front wheels in a turn
✓
QUESTION 16 / 25
Why keep the rear of the vehicle close to the curb during a right turn while still turning wide enough?
Choose one answer below.
A
To discourage drivers from passing on the right
✓
B
To lock trailer brakes
✓
C
To raise landing gear
✓
D
To avoid mirror use
✓
QUESTION 17 / 25
When backing a trailer, how do you initially steer?
Choose one answer below.
A
Turn as fast as possible
✓
B
Turn opposite the direction you want the trailer to go
✓
C
Always hold straight
✓
D
Steer like a straight truck
✓
QUESTION 18 / 25
Before backing into a tight area, what should you do?
Choose one answer below.
A
Rely only on a horn
✓
B
Use the hand valve to steer
✓
C
Get out and inspect path and clearances
✓
D
Close both mirrors
✓
QUESTION 19 / 25
The trailer hand valve should mainly be used to:
Choose one answer below.
A
Park overnight
✓
B
Stop normally in traffic
✓
C
Straighten a jackknife
✓
D
Test trailer brakes
✓
QUESTION 20 / 25
On newer vehicles, the trailer air supply control is usually:
Choose one answer below.
A
A red eight-sided knob
✓
B
A blue mirror switch
✓
C
A yellow light switch
✓
D
A green turn button
✓
QUESTION 21 / 25
How do you normally supply air to the trailer with the red knob?
Choose one answer below.
A
Twist it repeatedly
✓
B
Push it in
✓
C
Pull it out
✓
D
Remove it
✓
QUESTION 22 / 25
Which color commonly identifies the trailer service line?
Choose one answer below.
A
Purple
✓
B
White
✓
C
Blue
✓
D
Red
✓
QUESTION 23 / 25
Which color commonly identifies the emergency or supply line?
Choose one answer below.
A
Blue
✓
B
Purple
✓
C
Yellow only
✓
D
Red
✓
QUESTION 24 / 25
What part of glad hands helps prevent air loss?
Choose one answer below.
A
Rubber seals
✓
B
Mud flaps
✓
C
License plates
✓
D
Landing gear feet
✓
QUESTION 25 / 25
The kingpin locks into what part?
Choose one answer below.
A
Electrical socket
✓
B
Fifth wheel jaws
✓
C
Windshield frame
✓
D
Trailer tires
✓
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