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A. To park on a grade
B. Never
C. To park at loading docks
The trailer hand valve, also called the trolley valve or Johnson bar, works the trailer brakes. The trailer hand valve should be used only to test the trailer brakes. Never use the hand valve for parking because all the air might leak out unlocking the brakes.
2 / 25
A. Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolley: released
B. Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: applied
C. Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolley: applied
D. No answers are correct
Check for normal air pressure, release the parking brakes, release the service brake, make sure the trailer air supply is in / open, move the vehicle forward slowly, and apply trailer brakes with the hand control or trolley valve. You should feel the brakes come on. This tells you the trailer brakes are connected and working.
3 / 25
A. The trailer will be raised slightly when the tractor is backed under it
B. The kingpin is about 1 1/4 inches above the fifth wheel
C. The end of the kingpin is even with the top of the fifth wheel
The trailer should be low enough that it is raised slightly by the tractor when the tractor is backed under it. Raise or lower the trailer as needed. If the trailer is too low, the tractor may strike and damage the trailer nose; if the trailer is too high, it may not couple correctly.
4 / 25
A. Pull gently forward in low gear against the locked trailer brakes, then inspect the coupling
B. Rock the trailer back and forth with the trailer brakes locked
C. Put the tractor in gear and pull ahead with a sharp jerk
Raise trailer landing gear slightly off ground. Pull tractor gently forward while the trailer brakes are still locked to check that the trailer is locked onto the tractor.
5 / 25
A. Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: released
B. Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: applied
C. No answers are correct
D. Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolley: released
To test the trailer spring brakes, you need to have the service brake off or released, parking brake off, trailer air supply out shutting the door to the trailer, and trolley released.
6 / 25
A. Emergency trailer brakes to come on
B. Nothing will happen until air pressure reaches 10 PSI
C. Air compressor to unload instead of pumping air
D. Trailer supply valve will open
A major leak in the emergency line will cause the tractor protection valve to close and the trailer emergency brakes to come on. But the brakes will hold only if there is air pressure in the trailer air tank.
7 / 25
A. Pushing in the trailer air supply valve
B. Pulling out the trailer air supply valve
C. Connecting the service line glad hand
D. Pulling out the system parking brake
From cab, push in air supply knob or move tractor protection valve control from the emergency to the normal position to supply air to the trailer brake system.
8 / 25
A. Make sure that the brakes are properly adjusted
B. Keep the fifth wheel's free play as tight as possible
C. Go slowly around turns
The following two things will help you prevent rollover--keep the cargo as close to the ground as possible and drive slowly around turns.
9 / 25
A. The kingpin is about 1 1/4 inches above the fifth wheel
B. The end of the kingpin is even with the top of the fifth wheel
C. The trailer will be raised slightly when the tractor is backed under it
The trailer should be low enough that it is raised slightly by the tractor when the tractor is backed under it. Raise or lower the trailer as needed. If the trailer is too low, the tractor may strike and damage the trailer nose; if the trailer is too high, it may not couple correctly.
10 / 25
A. You can set the fifth wheel for weight balance
B. The parking lock is off, and you may drive away
C. The coupling is not right and should be fixed before driving the coupled unit
Check that the locking lever is in the lock position. If the locking lever does not go into the locked position the coupling is not complete.
11 / 25
A. End of the kingpin is even with the top of the fifth wheel
B. Trailer will be lifted slightly when the tractor backs under it
C. Trailer landing gear to be fully extended
The trailer should be low enough that it is raised slightly by the tractor when the tractor is backed under it. If the trailer is too low, the tractor may strike and damage the trailer nose; if the trailer is too high, it may not couple correctly.
12 / 25
A. make sure the ground is solid and can support the weight of the trailer.
B. call in for any special requests.
C. make sure the trailer has enough of an air supply for its brakes to hold.
Make sure surface of parking area can support weight of trailer.
13 / 25
A. coil it to keep it out of the way.
B. hang it with the plug up.
C. hang it with the plug down.
Hang electrical cable with plug down to prevent moisture from entering it.
14 / 25
A. pins
B. lug nuts
C. glad hands
Glad hands are coupling devices used to connect the service and emergency air-lines from the truck or tractor to the trailer.
15 / 25
A. radio in for assistance.
B. honk your horn loudly and call 911 or the posted emergency number.
C. get away from your vehicle and call 911 or the posted emergency number.
If for any reason you get stuck on the tracks, get out of the vehicle and away from the tracks. Check signposts or signal housing at the crossing for emergency notification information. Call 911 or another emergency number. Give the location of the crossing using all identifiable landmarks, especially the DOT number, if posted.
16 / 25
A. the tractor protection valve control (trailer air supply control) will pop out or go from "normal" to "emergency."
B. the parking brake valve will pop out.
C. the low air pressure warning signal will come on.
The tractor protection valve keeps air in the tractor or truck brake system should the trailer break away or develop a bad leak. The tractor protection valve is controlled by the "trailer air supply" control valve in the cab. The control valve allows you to open and shut the tractor protection valve. The tractor protection valve will close automatically if air pressure is low (in the range of 20 to 45 psi). When the tractor protection valve closes, it stops any air from going out of the tractor.
17 / 25
A. the brakes on the trailer wheels caused the skid in the first place.
B. the brake handle is too hard to reach.
C. the brakes on the trailer wheels will not respond to the hand brake.
When the wheels of a trailer lock up, the trailer will tend to swing around. This is more likely to happen when the trailer is empty or lightly loaded. This type of jackknife is often called a "trailer jackknife." Applying the trailer brakes would extend the skid and trailer jackknife.
18 / 25
A. it won't work as well as the foot brake.
B. of the danger of making the trailer skid.
C. you should use the parking brake.
Do not use it in driving because of the danger of making the trailer skid.
19 / 25
A. empty.
B. loaded to full capacity.
C. overloaded.
Large combination vehicles take longer to stop when they are empty than when they are fully loaded. When empty, the very stiff suspension springs and strong brakes give poor traction and make it very easy to lock up the wheels causing the tractor to jackknife.
20 / 25
A. always approach the trailer at a slight angle.
B. do it quickly to ensure that the kingpin is locked into the fifth wheel.
C. always use the lowest reverse gear.
Use lowest reverse gear. Back tractor slowly under trailer to avoid hitting the kingpin too hard, and stop when the kingpin is locked into the fifth wheel.
21 / 25
A. see it in your mirrors.
B. feel for "pulling" in the cab.
C. hear the wheels skidding.
The earliest way to notice that your trailer is jackknifing is to see it swinging out in your mirrors.
22 / 25
A. It is used to supply the trailer with air, shut the air off, and apply the trailer emergency brakes.
B. It is a six-sided yellow knob used to control the tractor protection valve.
C. It is a device used to keep the trailer behind the tractor.
The trailer air supply control on newer vehicles is a red eight-sided knob, which you use to control the tractor protection valve. You push it in to supply the trailer with air, and pull it out to shut the air off and put on the trailer emergency brakes.
23 / 25
A. It will keep dirt and water out of the lines.
B. The connected brake circuit becomes a backup air tank.
C. If you don't, you will never build system pressure.
Some vehicles have "dead end" or dummy couplers to which the hoses may be attached when they are not in use. This will prevent water and dirt from getting into the coupler and the air-lines.
24 / 25
A. Down
B. Up
C. Normal
To test the trailer air brake system, first charge it with air. Push in the red trailer air supply knob or place the tractor protection valve control in the "normal" position. Wait until the air pressure reaches normal before you start your tests.
25 / 25
A. five times more likely to roll over in a crash than empty rigs.
B. two times more likely to roll over in a crash than empty rigs.
C. ten times more likely to roll over in a crash than empty rigs.
When more cargo is piled up in a truck, the "center of gravity" moves higher up from the road. The truck becomes easier to turn over. Fully loaded rigs are ten times more likely to roll over in a crash than empty rigs.
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