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A. Never
B. To park on a grade
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: applied
B. No answers are correct
C. Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: applied
D. Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolley: released
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. Put the tractor in gear and pull ahead with a sharp jerk
C. Rock the trailer back and forth with the trailer brakes locked
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: in / open; Trolley: released
B. No answers are correct
C. Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: applied
D. Service Brake: off; Parking Brake: off; Trailer air supply: out; 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. Air compressor to unload instead of pumping air
B. Trailer supply valve will open
C. Emergency trailer brakes to come on
D. Nothing will happen until air pressure reaches 10 PSI
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. Connecting the service line glad hand
C. Pulling out the trailer air supply valve
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. Go slowly around turns
B. Keep the fifth wheel's free play as tight as possible
C. Make sure that the brakes are properly adjusted
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 end of the kingpin is even with the top of the fifth wheel
B. The trailer will be raised slightly when the tractor is backed under it
C. The kingpin is about 1 1/4 inches above 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.
10 / 25
A. The parking lock is off, and you may drive away
B. You can set the fifth wheel for weight balance
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 landing gear to be fully extended
C. Trailer will be lifted slightly when the tractor backs under it
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. call in for any special requests.
B. make sure the trailer has enough of an air supply for its brakes to hold.
C. make sure the ground is solid and can support the weight of the trailer.
Make sure surface of parking area can support weight of trailer.
13 / 25
A. hang it with the plug down.
B. hang it with the plug up.
C. coil it to keep it out of the way.
Hang electrical cable with plug down to prevent moisture from entering it.
14 / 25
A. pins
B. glad hands
C. lug nuts
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. get away from your vehicle and call 911 or the posted emergency number.
B. radio in for assistance.
C. honk your horn loudly 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 low air pressure warning signal will come on.
C. the parking brake valve will pop out.
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 brake handle is too hard to reach.
B. the brakes on the trailer wheels caused the skid in the first place.
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. you should use the parking brake.
B. it won't work as well as the foot brake.
C. of the danger of making the trailer skid.
Do not use it in driving because of the danger of making the trailer skid.
19 / 25
A. loaded to full capacity.
B. overloaded.
C. empty.
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. do it quickly to ensure that the kingpin is locked into the fifth wheel.
B. always approach the trailer at a slight angle.
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. hear the wheels skidding.
B. see it in your mirrors.
C. feel for "pulling" in the cab.
The earliest way to notice that your trailer is jackknifing is to see it swinging out in your mirrors.
22 / 25
A. It is a six-sided yellow knob used to control the tractor protection valve.
B. It is used to supply the trailer with air, shut the air off, and apply the trailer emergency brakes.
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. If you don't, you will never build system pressure.
C. The connected brake circuit becomes a backup air tank.
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. Up
B. Down
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. two times more likely to roll over in a crash than empty rigs.
B. five 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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