Illinois CDL Combination Test
After coupling, how much space should be between the upper and lower fifth wheel? -
ANSWER-no space
How can you test that air flows to all trailers: - ANSWER-listen - open the emergency line
shut off valve, you should hear air escaping
How can you test the tractor protection valve? - ANSWER-Charge trailer air brake system.
Shut off engine. Step on & off brake pedal. Control should pop out at 20-45 psi.
How can you test the trailer emergency brakes? - ANSWER-Charge the trailer air brake
system and check that the trailer rolls freely. Then stop and pull out the trailer air supply
control
How can you test the trailer service brakes? - ANSWER-Release parking brakes, move
forward slowly & apply trailer brakes with hand control
How do you know if your trailer is equipped with antilock brakes? - ANSWER-Yellow ABS
malfunction lamps on left side;ECU and wheel speed sensor wires coming from the back of
the brakes.
To drive you need to raise the landing gear only until it just lifts off the pavement. True or
False? - ANSWER-False
What does emergency air line do - ANSWER-It engages the trailer brakes in case of air
pressure loss.
What does the trailer air supply control do - ANSWER-red eight sided know which controls
the tractor protection valve
What is offtracking? - ANSWER-rear wheels follow a different path than front wheels
What is the service line for - ANSWER-Carries air to the trailer
What might happen if the trailer is too high when you try to couple? - ANSWER-it may not
couple correctly, you want king pin and 5th wheel aligned;trailer should be low enough so
tractor can be backed under it
What two things are important to prevent rollover? - ANSWER-Keep cargo as close to
ground and load centered on your rig
What type of trailers can get stuck on railroad-highway crossings? - ANSWER-Low slung
units and Single-axle tractor pulling a long trailer with its landing gear set to accommodate
a tandem-axle tractor.
After coupling, how much space should be between the upper and lower fifth wheel? -
ANSWER-no space
How can you test that air flows to all trailers: - ANSWER-listen - open the emergency line
shut off valve, you should hear air escaping
How can you test the tractor protection valve? - ANSWER-Charge trailer air brake system.
Shut off engine. Step on & off brake pedal. Control should pop out at 20-45 psi.
How can you test the trailer emergency brakes? - ANSWER-Charge the trailer air brake
system and check that the trailer rolls freely. Then stop and pull out the trailer air supply
control
How can you test the trailer service brakes? - ANSWER-Release parking brakes, move
forward slowly & apply trailer brakes with hand control
How do you know if your trailer is equipped with antilock brakes? - ANSWER-Yellow ABS
malfunction lamps on left side;ECU and wheel speed sensor wires coming from the back of
the brakes.
To drive you need to raise the landing gear only until it just lifts off the pavement. True or
False? - ANSWER-False
What does emergency air line do - ANSWER-It engages the trailer brakes in case of air
pressure loss.
What does the trailer air supply control do - ANSWER-red eight sided know which controls
the tractor protection valve
What is offtracking? - ANSWER-rear wheels follow a different path than front wheels
What is the service line for - ANSWER-Carries air to the trailer
What might happen if the trailer is too high when you try to couple? - ANSWER-it may not
couple correctly, you want king pin and 5th wheel aligned;trailer should be low enough so
tractor can be backed under it
What two things are important to prevent rollover? - ANSWER-Keep cargo as close to
ground and load centered on your rig
What type of trailers can get stuck on railroad-highway crossings? - ANSWER-Low slung
units and Single-axle tractor pulling a long trailer with its landing gear set to accommodate
a tandem-axle tractor.
