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106 Cards in this Set
- Front
- Back
What 3 braking systems do air brakes use?
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Service, Parking, and emergency.
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What does a service brake do?
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Applies and releases brakes when you press break pedal during normal driving.
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What does the parking brake do?
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Applies and releases the parking brakes when you use the parking brake control.
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What does the emergency brake do?
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Uses both parking and service brake systems to stop the vehicle in case of brake failure.
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How many parts of the air brake system are there?
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23
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What are the 23 parts of the air brake system?
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1. Air compressor, 2. Air Compressor Governor, 3. Air storage tanks, 4. Air Tank Drains, 5, Alcohol Evaporator, 6. Safety Valve, 7. Brake Pedal, 8. Foundation Brakes, 9 Brake Drums, 10 foundation brakes, 11. Brake drums/ shoes/linings. 12 S-Cam Brakes. 13 Wedge Brakes, 14 Disc Brakes, 15. supply pressure Gauge, 16Application pressure gauge, 17 Low Air pressure Gauge, 18. Stop light Switch, 19. Front Brake limiting valve, 20. spring brakes, 21 Parking brake controls, 22, Modulating control valves, 23 Dual parking control valves.
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What is the Air compressor?
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Pumps air into storage tanks, connected to engine through V-belt, may have own oil or use engine oil, cooled by by engine cooling system or air.
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What is the air governor?
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controls air pumped into storage tanks, cut off at around 125lbs.
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What are the air storage tanks?
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Holds the compressed air.
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What are the Air Tank Drains?
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water and oil collected in the bottom of the air storage tank which is bad, these help drain them.
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What are the two types of drains?
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manual and automatic.
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How do you operate manual drain systems?
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by turning a quarter turn or by pulling a cable. Must be emptied at the end of each driving day.
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How do you operate an automatic drain systems?
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Its automatic.
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What is the alcohol evaporator?
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The alcohol prevents freezing of the valves which can make the brakes stop working.
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What maintenance is needed on the alcohol evaporator?
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Fill up as necessary every day during cold weather and air tank drainage is needed to get rid of the water.
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What is the safety valve?
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It protects the tanks from too much air pressure installed in the first tank set to open at 150psi.
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Foundation brakes?
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Are used in each wheel
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What are the parts of the foundation brakes?
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Drums, shoes and linings.
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What is the S-cam brakes?
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Its the mechanism for braking shaped like an S, push the brake pads away from each other against the drum when the brake is pushed.
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What are the wedge brakes?
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Uses a wedge instead of a S to push the brake pads apart.
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What is the Modulating Control Valves?
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A lever that controls the spring break, located on the dash board.
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What is the dual parking control valves?
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This is the other push/pull button on the spring brakes.
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What is the dual air brake system?
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Air brake system with primary and secondary tanks.
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What do you check on the engine compartment for the air brakes?
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You check the air compressor drive belt for tightness and condition.
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How do you check the manual slack adjustments on S cam brakes?
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Park on level ground and chock the wheels to prevent the vehicle from moving. Torn off the parking break so you can move the slack adjusters.
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How do you check the brake drums or disks?
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The must not have cracks longer then one-half the length of the friction area.
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How do you check the linings(friction material)?
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Must not have oil or grease on them, must be in place and not broken or missing.
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How do you check the hoses?
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air hoses must be connected to the air brake chamber.
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What do you have to check on the final air brake check?
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Test low pressure warning signal, Check spring brakes to see if the come on automatically, Check rate of air pressure buildup, test air leakage rate, check air compressor governor cut-in and cut-out pressures, test parking brake, test service brake.
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How do you check the low pressure warning signal?
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Shut off engine. pump brake pedal to reduce pressure in tanks and it should come on.
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How do you check for air leakage rate?
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fully charged at typically 125psi and should drop off at less then 2 psi per minute.
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How do you test the parking brake?
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stop the vehicle put the parking brake on and gently pull against it in low gear to test that the parking brake will hold.
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How do you test the service brake?
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push the brake pedal and see if it pulls to one side.
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How many factors are there to take into consideration when braking?
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10
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What are the 10 factors?
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Brake fading/failure, proper braking technique, low air pressure, parking brakes, stopping distance,normal stops, emergency stops, controlled braking, and anti-lock brakes.
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How do you do a Normal stop?
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Push pedal down, do not hit clutch until RPM is near idle then start selecting the gear.
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How can you brake in Emergency situations?
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Brake in a straight line and make sure you are able to turn the vehicle slightly if necessary, use the stabbing method if possible.
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How do you use controlled braking?
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keep the vehicle in a straight line. Use the stab brake method if necessary.
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How do you stab brake?
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Push the brake as hard as you can, the wheels will lock, when they start rolling again hit the brake again.
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How do you know if a vehicle has anti-lock brakes?
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There will be a light on the dashboard indicating it.
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What are the four factors to total stopping distance?
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Reception distance
Reaction distance Brake lag distance Effective braking distance. |
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On good traction how long would it take to stop?
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300ft, which is longer than a football field.
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What are the three steps to proper braking technique?
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1. Apply the brakes just hard enough to feel a definite slow down.
2. When your speed has been reduced to approximately 5mph below your "safe" speed, release the brakes(about 3 seconds) 3. When your speed has increased to your "safe" speed, repeat steps 1 and 2. |
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What do you do if you have low air pressure?
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Stop and safely park as soon as possible. If pressure is too low, load is too heavy, or roads are too slippery you may loose control of the truck.
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How do you use the parking brake?
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pull the parking brake control knob out to apply the breaks, push it in to release it. the control will be a yellow diamond shaped knob.
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What not to do with the parking brakes?
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Do not use when very hot(after coming down steep grade). Do not use when freezing.
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What do you do when its freezing before using the parking brakes?
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Use the brakes lightly while driving to dry them in a low gear. This will heat and dry them.
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What is the leading cause of death for truck drivers?
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Rollovers
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What increases the risk of rollovers by 10 fold?
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Full rigs.
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What helps prevent rollovers?
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Keeping the cargo close to the ground as possible and going as slow as possible while turning. Drive slowly around corners ramps and off ramps, and avoid quick lane changes.
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What is rearward amplification?
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This happens when only the cargo can roll over. This known as the crack the whip effect.
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How do you counteract the rearward amplification?
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steer gently. Brake early.
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What causes a trailer jackknife to be more likely?
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A lightly loaded trailer and trailer skidding.
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What are the two steps to stop skidding?
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recognize the skid and stoop using the brakes.
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How do you recognize a skid?
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by looking in the rear view mirrors to see if the trailer is swaying.
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How many parts are there involved in the trailer braking system?
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10
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What are the 10 Parts to the trailer air braking system?
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1. Trailer hand Valve, tractor protection valve, Trailer air supply control, trailer air lines, service air line, emergency air line, hose couplers, trailer air tanks, shut-off valves, trailer service, parking and emergency brakes.
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What is the trailer hand valve?
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also called the trolly valve or johnson bar, works on the trailer brakes only.
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What is the tractor protection valve?
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Push pull button valve on the console. Push to supply trailer with air and pull it out to shut the air off.
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What are the trailer air lines?
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the service line and the emergency line they run between the tractor to trailer.
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What does the service line do?
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carries air activated by the foot brake to the trailer.
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What does the emergency air line do?
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Supply air to the trailer air tanks and to control the emergency brakes on combination vehicles.
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What can loss of pressure in the emergency brake system cause?
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it could cause the brakes to come on.
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How can you tell apart the emergency lines with the service lines?
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emergency lines are usually red and service lines are blue.
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What are hose couplers or glad hands?
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Coupling devices used to connect the service and emergency air lines from the truck or tractor to the trailer. The couplers have a rubber seal that prevents air from escaping.
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How do you maintain the glad hands?
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Clean the couplers before a connection is made.
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How do you connect the glad hands?
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Press the two seals together with the couplers at a 90-degree angle to each other. A turn of the glad hand attached to the hose will join and lock the couplers.
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What is the dead end refereed to on the glad hands?
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when there not in use there used to keep water and dirt from getting in to the coupler and air lines.
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How do you check the trailer brakes?
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Drive with the hand valve or by pulling against them in a low gear gently.
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What are the Trailer Air Tanks?
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each trailer and converter dolly has one or more air tanks. they are filled by the emergency supply line from the tractor.
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What are the Shut off valves?
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Are used in the service and supply air lines at the back of trailer used used to tow other trailers.
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How many steps are there to coupling?
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16
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What are the 16 steps of coupling?
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1. Inspect the fifth wheel. 2. Inspect area and chock wheels. Step 3. Position Tractor. Step 4 Back Slowly. Step 5. Secure Tractor. Step 6. Check Trailer Height. Step 7. Connect Air lines to Trailer. Step 8. Supply Air to Trailer. Step 9. Lock Trailer Brakes. Step 10. Back under Trailer. Step 11. Check Connection for Security. Step 12. Secure Vehicle. Step 13. Inspect Coupling. Step 14. Connect the electrical Cord and Check Air Lines. Step 15. Raise Front Trailer supports. Step 16. Remove Trailer Wheel Chocks.
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What do you do in the 1st step of coupling?
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Check for damaged/missing parts. Check to see that mounting to tractor is secure, no cracks in frame. Be sure that the fifth wheel plate is greased as required. Failure to keep the fifth Wheel plate lubricated could cause steering problems because ofthe friction between the tractor and trailor.
Check the fifth wheel is in proper position for coupling. Wheel tilted down towards rear of tractor, Jaws Open, Safety unlocking handle in the automatic lock position. If you have a sliding fifth wheel, make sure it is locked. Make sure the trailer kingpin is not bent or broken. |
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What do you do in the 2nd step of coupling
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Inspect area and chock wheels.
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What is involved in inspecting area and chock wheels?
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Make sure area around the vehicle is clear. Be sure trailer wheels are chocked or spring brakes are on. Check the cargo is secured against movement due to tractor being coupled to the trailer.
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What is involved in step 3 of coupling.
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Position tractor. Put the tractor directly in front of the trailer, never back under the trailer at an angle because you might break the gear. Check position using outside mirrors by looking down both sides of the trailer.
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What is involved in the 4th step of coupling.
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Back slowly until 5th wheel touches the trailer do not hit the trailer.
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What is involved in the 6th step of coupling.
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Check the trailer height. The trailer should be low enough that it is raised slightly by the tractor when the tractor is backed under it. check that the kingpin and fifth wheel are aligned.
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What is involved in the 7th step of coupling.
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Connect the air lines to the trailer. Make sure the glad hands are secure well.
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What is the 8th step of coupling?
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Supply air to the trailer.
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How do you supply air to the trailer?
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Push in air supply knob in the trailer. check for crossed lines. shut off engine so you can hear the lines. apply and release trialer brakes and listen for sound of trailer brakes being applied and released you should hear the brakes move when applied and air escaped when the brakes are released. When you are sure brakes are working you should start the engine. Make sure air pressure is up to normal.
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What is step 9?
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Lock trailer brakes Pull out "air supply knob. or move tractor protection valve control from "normal" to emergency"
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Step 10: back under trailer.
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Use lowest reverse gear. Back tractor slowly under trailer to avoid hitting kingpin too hard. Stop when the kingpin is locked into the fifth wheel.
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What is the 11th step?
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Check connection for security, raise trailer landing gear slightly off ground. Stop when the kingpin is locked into the fifth wheel.
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What is the 12 step under secure vehicle
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Put transmission in neutral, put parking brakes on. Shut off engine and take key with you so someone else will not move truck while you are under it.
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What is step 13 of coupling?
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inspect the coupling.
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How do you inspect the coupling?
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no space between upper and lower fifth wheel. Go under trailer and look into the back of the fifth wheel. IF the coupling is not right, do not drive the coupled unit: get it repaired.
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What is the 14th step of coupling?
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Connect the electrical cord and check air lines.
Plug the electrical cord into the trailer and fasten the safety latch. Check both air lines and electrical line for signs of damage. Make sure air and electrical lines will not hit any moving parts of the vehicle. |
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What is the 15th step of coupling?
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Low gear to begin raising land gear. once free of weight, switch to the high gear range.
After raising landing gear secure the crank. |
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What is the 16th step of coupling?
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remove trailer wheel chocks remove and store wheel chocks in a safe place.
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How many steps are there to UN-cupuling a vehicle?
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there are 10 steps in uncoupling a vehicle.
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What is the first step of uncupoling?
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positioning the rig
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How do you position the rig?
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Make sure surface of parking area can support weight of trailer.
Have tractor lined up with the trailer. |
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What is step two of locking jaws?
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shut off trailer air supply to lock trailer brakes.
Ease pressure on fifth wheel locking jaws by backing up gently(this will help you release the fifth wheel locking lever). Put on parking brakes while tractor is pushing against the kingpin. |
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What is step 3?
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Chock trailer wheels.
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How do you chock trailer wheels?
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use the emergency brakes.
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What is the 4th step of uncuppuling?
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if trailer is empty, lower the landing gear until it makes firm contact with the ground.
IF the trailer is loaded, crank it extra. lowering the landing gear |
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What is the 5th step in uncoupling?
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Disconnect Air lines and electrical cable.
Disconnect air lines from trailer. Connect air line glad hands to dummy couplers at back of cab or couple them together. Hang electrical cable with plug down to prevent moisture from entering it. Make sure lines are supported so they will not be damaged while driving the tractor trailer. |
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What is the 6th step of uncoupling?
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Unlock the fifth wheel.
Raise release handle lock. Pull the release handle to "open" position. Keep legs and feet clear of the rear tractor wheels to avoid serious injury in case of vehicle moves. |
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What is the 7th step of uncoupling?
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Pull tractor partially clear of trailer.
Pull tractor forward until fifth wheel comes out from under the trailer. Keep legs and feet clear of the rear tractor wheels to avoid serious injury in case the vehicle moves. |
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What is the 8th step of uncoupling?
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Secure Tractor
Apply parking brake Stop with tractor frame under trailer. |
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What is the 9th step of uncoupling?
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Inspect trailer supports
Make sure ground is supporting trailer Make sure landing gear is not damaged. |
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What is the 10th step of uncoupling?
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Pull tractor clear of trailer
Release parking brakes Check the area and drive tractor froward until it clears. |
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What must you do after coupling the vehicle?
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inspect the vehicle.
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What is involved in checking the air flow to all trailers?
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Put on the emergency air brake. Go to the back of the rig open the emergency line shut off valve, you should hear air escaping this means the air tank is full.
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