CDL Combination Vehicles

You supply air to the trailer tanks by:

A: pushing in the trailer air supply valve

B: pulling out the trailer air supply valve

C: connecting the service air line

Pushing in the trailer air supply valve.

Loss of air pressure in the emergency line causes:

A: the relay valves to close

B: an increase in air pressure to the service line

C: the trailer's emergency brakes to come on

the trailer's emergency brakes to come on

A tractor with a ___trailer requires the shortest amount of stopping distance.

A: empty

B: lightly loaded

C: fully loaded

fully loaded

Which of these statements are true?

A. the brake and suspension of combination vehicles work best with a light load

B: light vehicles need more braking power to stop than heavy ones

C: bobtails tractor can take longer to stop than fully loaded combination vehicles

bobtails tractor can take longer to stop than fully loaded combination vehicles

If you cannot make a right turn without swinging into another lane, you should:

A: swing wide before you make the turn

B: turn wide as you complete the turn

C: not make that turn. Go to another place to turn.

turn wide as you complete the turn

The tractor protection valve will close and the trailer emergency brakes will come on when there is a major leak in what air line?

A: service

B: emergency

C: parking

emergency

Off tracking or "cheating" causes which of these to follow the widest path while making a turn?

A: 3 axle tractor towing a 45 foot trailer

B: 3 axle tractor towing two 27 foot trailers

C: A bobtail tractor

3 axle tractor towing a 45 foot trailer

If your vehicle gets stuck on a railroad crossing, you should:

A: use reverse to back of the tracks

B: get out of the vehicle and away from the tracks

C: turn on your 4-way flashers

get out of the vehicle and away from the tracks

When driving a set of double trailers, it is necessary to close shut-off valves on some trailers. Where are these valves located?

A: in the front of trailers

B: in the middle

C: at the back of trailers used to tow other trailers

at the back of trailers used to tow other trailers

Before you back under a trailer, make sure of what?

A: the trailer brakes are locked

B: the air supply knob is in

C: the air brakes are off

the trailer brakes are locked

To unlock the fifth wheel, you pull the handle to what position?

A: open

B: neutral

C: closed

open

After connecting the air lines but before backing under the trailer, you should:

A: supply air to the trailer, then pull out the trailer air supply valve

B: make sure that the trailer brakes are off

C.: walk around the rig to be sure it is clear

supply air to the trailer, then pull out the trailer air supply valve

You are coupling a tractor to a semi-trailer and you have backed up but are not yet under it. What should you hook up before backing under it?

A: the emergency and service air lines

B: the electric line

C: nothing, back up and lock the fifth wheel

the emergency and service air lines

You are coupling a tractor to a trailer. The trailer is at the right height when:

A: the kingpin is about 1 inch above the fifth wheel

B: the end of the kingpin is even with the top of the fifth wheel

C: the trailer is raised slightly when the tractor is backed under it

the trailer is raised slightly when the tractor is backed under it

Why should you connect the air lines to a dummy coupler when they are not in use?

A: the connected circuit becomes a back up air tank

B: it will keep dirt and water out of the lines

C. if you don't you will never build pressure in the system

it will keep dirt and water out of the lines

The air leakage rate for a combination vehicle with the engine off and the brakes off should be less than ___ per minute.

A: 1 PSI

B: 2 PSI

C: 3 PSI

2 PSI

Air and electric lines from the tractor to the trailer should be:

A: pulled tight with very little slack

B: secured properly with enough slack for turns

C: resting on the frame of the tractor

secured properly with enough slack for turns

Air brake equipped trailers made before 1975:

A: often do not have spring brakes

B: usually need a glad hand converter

C: cannot be legally operated on interstate highways

often do not have spring brakes

The hand valve should be used:

A: only with the foot pedal

B: to test the trailer brakes

C: as a parking brake

to test the trailer brakes

The air leakage rate for a combination vehicle with the engine off and the brakes on should be less than ___ per minute.

A: 2 PSI

B: 3 PSI

C: 4 PSI

4 PSI

Your emergency line breaks or gets pulled apart while driving. The loss of pressure will cause the:

A: emergency trailer brakes to come on

B: air compressor to unload instead of pumping

C: trailer supply valve to open

emergency trailer brakes to come on

You have pushed in the trailer air supply valve. You should not move the vehicle until the whole system is:

A: empty

B: at normal pressure

C: between 60 and 80 PSI

at normal pressure

When should you use the hand valve to park a combination vehicle?

A: to park at loading docks

B: to park on a grade

C: never

never

The best way to tell that your trailer has started to skid is to:

A: hear the wheels skidding

B: see it in your mirrors

C: feel the cab pulling

see it in your mirrors

A trailer is most likely to jackknife when it is:

A: loaded to full capacity

B: over loaded

C: empty

empty

If the service line comes apart but the emergency line stays together, what will happen right away?

A: the trailer's air tank will exhaust through the open line

B: the trailer emergency brakes will come on

C: nothing is likely to happen until you try to apply the brakes

nothing is likely to happen until you try to apply the brakes

When backing a tractor under a trailer you should:

A: always use the lowest reverse gear

B: always approach the trailer at a slight angle

C: do it quickly to ensure the trailer does not move

always use the lowest reverse gear

After you have coupled the trailer, you should begin raising the landing gear using what gear?

A: low gear

B: mid-level gear

C: high gear

low gear

You will know the trailer you are using has ABS by:

A: a red malfunction lamp on the trailer

B: a yellow malfunction lamp on the left side

C: a yellow malfunction lamp on the right side

a yellow malfunction lamp on the left side

If you cross the air lines while coupling to an old trailer what will happen?

A: the hand valve will apply the tractor brakes instead of the trailer brakes

B: if the trailer has no spring brakes, you could drive away but you would not have trailer brakes

C: the brake pedal will work the spring brakes instead of the service brakes

if the trailer has no spring brakes, you could drive away but you would not have trailer brakes

When should you get out of your vehicle when you are backing a trailer?

A: you should never get out while backing

B: when you are unsure of your path of travel

C: when your trailer begins to drift to the passenger side

when you are unsure of your path of travel

When you are uncoupling a loaded trailer, you should lower the landing gear until it:

A: makes firm contact with the ground, then turn it a few extra cranks in low gear

B: makes contact with the ground and lifts the trailer off the fifth wheel

C: just reaches the ground

makes firm contact with the ground, then turn it a few extra cranks in low gear

How much space should be between the upper and lower fifth wheel after coupling?

A: about ¼ inch

B: just enough to see light through it

C: none

none

The front trailer supports are up and the trailer is resting on the tractor. Make sure:

A: there is enough clearance between the upper and lower fifth wheel

B: the safety latch is in the unlocked position

C: there is enough clearance between the frame and the landing gear

there is enough clearance between the frame and the landing gear

Why should you be sure that the fifth wheel is greased as required? A: to ensure good electrical connection

B: to prevent steering problems

C: to reduce heat and noise

to prevent steering problems

After you lock the kingpin into the fifth wheel, you check the connection by:

A: pulling forward 50 feet, turning left and right

B: pulling the tractor ahead sharply to release the trailer brakes

C: pulling the tractor ahead gently with trailer brakes locked

pulling the tractor ahead gently with trailer brakes locked

After you supply air to the trailer, make sure the lines are not crossed and the brakes are working. This is done by:

A: turning on the parking brakes in the cab

B: watching your mirrors to see if your trailer lights are working C: applying and releasing the trailer brakes and listening for sounds

applying and releasing the trailer brakes and listening for sounds

To be safe while driving, you should leave at least 1 second for every ___ feet of vehicle length as following distance.

A: 10

B: 20

C: 30

10

Two things you can do to prevent rolling over are keep the cargo as low to the ground as possible, and:

A: make sure the brakes are adjusted properly

B: keep both hands firmly on the wheel

C: go slow around turns

go slow around turns

You have a major leak in the service line and you put on the brakes. Service air pressure will escape and if it goes low enough will cause the:

A: trailer emergency brakes to come on

B: trailer tank pressure to be lost

C: tractor spring brakes to come on

trailer emergency brakes to come on

When uncoupling a trailer, after you have locked the trailer brakes, you should:

A: back up gently to ease pressure on the fifth wheel jaws

B: begin to lower the landing gear

C: immediately put on the tractor brakes

back up gently to ease pressure on the fifth wheel jaws

When do you need to use chocks to park a trailer that does not have spring brakes?

A: never

B: always

C: only when it is parked on a hill

always

The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means:

A: the trailer will not swivel on the fifth wheel

B: the parking brakes are off and you may drive away

C: the coupling is not right and should be fixed before driving

the coupling is not right and should be fixed before driving

When you get ready to back under a trailer, you should line up:

A: the kingpin to engage the driver-side jaws firsts

B: directly in front of the trailer

C: the drive wheel with the kingpin

directly in front of the trailer

After you have coupled to a trailer, the tractor protection valve should be placed in the ___ position.

A: down

В: up

C: normal

normal

How should you test the trailer connection for security?

A: rock the trailer back and forth with the trailer brakes locked

B: put the tractor in gear and pull ahead with a sharp jerk

C: pull gently forward with the trailer brakes locked, then look at it carefully

pull gently forward with the trailer brakes locked, then look at it carefully

The trailer air supply valve should automatically close when air pressure falls to what range?

A: 20-45 PSI

B: 60-80 PSI

C: 100-125 PSI

20-45 PSI

What part of the kingpin should the jaws be locked around?

A: the shank

B: the base

C: the head

the shank

The higher your center of gravity of your truck, the:

A: easier it is to turn around corners

B: more it is affected by the wind

C: easier it is to turn over

more it is affected by the wind

When checking that the trailer is securely coupled to the tractor, the landing gear should be:

A: fully raised

B: slightly raised

C: fully lowered

slightly raised

If you must back your trailer on a curved path, you should position your vehicle so you can back:

A: in a straight line

B: to the driver's side

C: to the passenger side

to the driver's side

If your ABS is not working on your trailer, you should:

A: not drive until the system is repaired

B: drive normally, but get the system serviced soon

C: drive at a slower speed

drive normally, but get the system serviced soon

Compared to a straight truck or bus, there are ___ things to inspect on a combination vehicle.

A: fewer

B: equal

C: more

more

Air lines are often colored. The emergency line is? The service line is?

A: red, blue

B: black, yellow

C: blue, red

red, blue

To stop a trailer skid you should?

A: use the trailer hand brake

B: release the service brakes

C: counter-steer

release the service brakes

What gear should the transmission be in after you have uncoupled and are inspecting the trailer supports?

A: low reverse

B: neutral

C: high reverse

neutral

You have coupled to a trailer. Where should the landing gear be before driving away?

A: raised halfway with the handle secure

B: raised ¾ of the way

C: fully raised with the crank handle secure in the bracket

fully raised with the crank handle secure in the bracket