5-64.
Overuse of brakes can cause too
much heat to be generated, and
this condition can result in
brake failure.
1.
True
2.
False
5-65.
When you are operating a tractor–
trailer, the power springs on the
spring brakes are held back by what
force?
1.
Gravity
2.
Mechanical linkage
3.
Hydraulic fluid
4.
Air pressure
5–66.
Tractor and straight truck spring
brakes engage when the air pressure
drops to what pressure range?
1.
20 to 45 psi
2.
45 to 60 psi
3.
60 to 80 psi
4.
80 to 90 psi
5-67.
A diamond shaped, yellow push–pull
control knob is used to engage or
disengage what component on a
tractor?
1.
The fifth-wheel lock
2.
The front axle PTO shaft
3.
The parking brakes
4.
The differential lock
5-68.
What term is used to describe
applying the brakes as hard as
possible without locking the
wheels?
1.
Severe braking
2.
Controlled braking
3.
Panic braking
4.
Stab braking
5–69.
You should NOT use the trailer
hand valve because of the danger
of making the trailer skid.
1.
True
2.
False
5-70.
What condition(s) result when the
tractor protection valve closes?
1.
Air is kept from escaping
from the tractor only
2.
The air compressor is shut
down only
3.
Air from the tractor emergency
line is shut off and the air
compressor is activated
4.
Air from the trailer emergency
line is shut off and air is
kept from escaping from the
tractor
5-71.
What is the name of the line that
carries air to the trailer and is
controlled by the foot valve or
trailer hand brake?
1.
Service
2.
Emergency
3.
Drive
4.
Electrical
5–72.
As pressure increases in the
service line, what valve opens
and sends air pressure from the
trailer air tanks to the trailer
brake chambers?
1.
The release
2.
The protector
3.
The relay
4.
The jet
5–73.
What is the function of the
emergency line?
1.
Sends air to the relay valve
only
2.
Supplies air to the trailer
air tanks only
3.
Sends air to the relay valve
and controls the emergency
brakes on combination vehicles
4.
Supplies air to the trailer air
tanks and controls the
emergency brakes on combination
vehicles
5-74.
What is the name of the rubber
seals that are on the glad hand?
1.
Rubber washer
2.
Rubber grommet
3.
Rubber gasket
4.
Rubber mate
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