Pass by the Book

Emergencies, ABS and skids

Practice this topic68 questions

Questions and answers

  1. What is the difference between a traffic emergency and a vehicle emergency?

    A traffic emergency is two vehicles about to collide, a vehicle emergency is a part failing

    Traffic emergencies are near-collisions, vehicle emergencies are failures of tires, brakes or other critical parts.

    Section 2 · 2.17 – Driving Emergencies ↗PDF, 41 MB
  2. In an emergency, which can you usually do more quickly?

    Turn to miss an obstacle

    You can almost always turn to miss an obstacle faster than you can stop, though top-heavy vehicles may flip.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  3. Which vehicles may flip over when steering quickly to avoid a crash?

    Top-heavy vehicles and tractors with multiple trailers

    Quick steering is usually faster than stopping, but top-heavy rigs and multiple trailers may roll.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  4. What is the best way to have both hands on the wheel in an emergency?

    Keep them there all the time

    To turn quickly you need a firm two-hand grip, so keep both hands on the wheel at all times.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  5. Should you brake while making a quick turn to avoid a crash?

    No, it is very easy to lock the wheels while turning

    Braking during the turn can lock the wheels and cause a skid.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  6. How sharply should you turn to avoid an obstacle?

    No more than needed to clear it

    The sharper you turn, the greater the chance of a skid or rollover.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  7. What does counter-steering mean?

    Turning the wheel back the other way once you have passed the obstacle

    Emergency steering and counter-steering are two parts of one driving action.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  8. An oncoming driver has drifted into your lane. Which way is it best to move?

    To your right

    If the other driver notices, the natural response is to return to his own lane, which a move left would block.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  9. If you are blocked on both sides, which move may be best?

    A move to the right

    Going right at least avoids forcing anyone into the opposing lane and a possible head-on collision.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  10. How do you know which lane is empty when you must steer around something?

    By having been using your mirrors

    If you check your mirrors regularly, you already know which lane is free.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  11. Can most shoulders support the weight of a large vehicle?

    Yes, most are strong enough and offer an escape route

    Most shoulders can hold a large vehicle, so driving off the road may be less risky than a collision.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  12. When leaving the road in an emergency, until what speed should you avoid braking if possible?

    About 20 mph

    Wait until your speed drops to about 20 mph, then brake very gently to avoid skidding.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  13. When you drive off the road in an emergency, what helps you keep control?

    Keeping one set of wheels on the pavement, if possible

    One set of wheels on the pavement helps maintain control.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  14. If you must return to the road before you can stop, how should you do it?

    Hold the wheel tightly and turn sharply enough to get right back on

    Edging back slowly can make the tires grab unexpectedly and cause loss of control.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  15. Returning to the road from the shoulder, when should you counter-steer?

    As soon as both front tires are on the paved surface

    Counter-steer immediately when both front tires are on the pavement, in one steer-counter-steer move.

    Section 2 · 2.17.1 – Steering to Avoid a Crash ↗PDF, 41 MB
  16. How do you use the controlled braking method?

    Brake as hard as you can without locking the wheels

    Controlled braking means maximum braking short of lockup, with very small steering movements.

    Section 2 · 2.17.2 – How to Stop Quickly and Safely ↗PDF, 41 MB
  17. During controlled braking, what should you do if the wheels lock?

    Release the brakes, then re-apply as soon as you can

    If the wheels lock or you need a larger steering change, release and re-apply the brakes.

    Section 2 · 2.17.2 – How to Stop Quickly and Safely ↗PDF, 41 MB
  18. How do you use the stab braking method?

    Brake fully, release when wheels lock, re-apply when they roll

    In stab braking you apply the brakes all the way, release on lockup, then apply fully again once the wheels roll.

    Section 2 · 2.17.2 – How to Stop Quickly and Safely ↗PDF, 41 MB
  19. In stab braking, how long can it take the wheels to start rolling after you release the brakes?

    Up to one second

    Wait for the wheels to roll before re-applying, or the vehicle will not straighten out.

    Section 2 · 2.17.2 – How to Stop Quickly and Safely ↗PDF, 41 MB
  20. What happens if you jam on the brakes as hard as you can in an emergency?

    The wheels stay locked and the vehicle skids

    Locked wheels cause a skid, and you cannot control a skidding vehicle.

    Section 2 · 2.17.2 – How to Stop Quickly and Safely ↗PDF, 41 MB
  21. What are the two main reasons hydraulic brakes fail?

    Loss of hydraulic pressure and brake fade on long hills

    Most hydraulic brake failures come from loss of pressure or fade on long hills.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  22. How does the brake pedal feel when a hydraulic system will not build pressure?

    Spongy, or it goes to the floor

    Loss of hydraulic pressure makes the pedal spongy or lets it sink to the floor.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  23. Why can the parking brake slow you when the hydraulic brakes fail?

    It is separate from the hydraulic brake system

    The parking brake is separate, so use it while holding the release to keep the wheels from locking.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  24. When using the parking brake to slow after hydraulic failure, how do you keep the wheels from locking?

    Hold the release button or lever at the same time

    Working the release while applying lets you adjust the pressure.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  25. With hydraulic brake failure, what is a good way to slow and stop?

    Turning uphill

    While slowing, look for an escape route, and turning uphill helps stop the vehicle.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  26. What will almost always prevent brake failure on long downgrades?

    Going slow enough and braking properly

    Proper speed and braking prevent failure, but once brakes fail you need something outside the vehicle to stop.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  27. Where are escape ramps usually located?

    A few miles from the top of the downgrade

    Ramps usually sit a few miles down from the top, and signs tell you about them.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  28. If your brakes fail going downhill and no escape ramp is available, what should you do?

    Take the least hazardous escape route as soon as you know

    Move to an open field or a side road that flattens or turns uphill at once, since speed keeps building.

    Section 2 · 2.17.3 – Brake Failure ↗PDF, 41 MB
  29. You hear a tire blow but are not sure it is yours. What should you assume?

    That it is yours

    It can take a few seconds for your vehicle to react, so assume any blowout you hear is yours.

    Section 2 · 2.17.4 – Tire Failure ↗PDF, 41 MB
  30. With a rear tire failure, what may be the only sign you get?

    Thumping or heavy vibration

    A flat rear tire may show only as thumping or vibration.

    Section 2 · 2.17.4 – Tire Failure ↗PDF, 41 MB
  31. If the steering feels heavy, what has probably happened?

    A front tire has failed

    Heavy steering is probably a sign that a front tire failed.

    Section 2 · 2.17.4 – Tire Failure ↗PDF, 41 MB
  32. What usually prevents fishtailing when a rear tire fails?

    Dual rear tires

    A failed rear tire can make the vehicle fishtail, but duals usually prevent it.

    Section 2 · 2.17.4 – Tire Failure ↗PDF, 41 MB
  33. When a tire fails, what should you do with the brakes?

    Stay off them until the vehicle slows, unless about to hit something

    Braking with a failed tire can cause loss of control, so slow down first and then brake gently.

    Section 2 · 2.17.4 – Tire Failure ↗PDF, 41 MB
  34. Why should you check all tires after stopping for a tire failure, even if the vehicle handles fine?

    A failed dual tire may only be found by looking

    If one of your duals goes, getting out and looking may be the only way to know.

    Section 2 · 2.17.4 – Tire Failure ↗PDF, 41 MB
  35. What does ABS do?

    Keeps the wheels from locking up during hard braking

    ABS is a computerized system that prevents wheel lockup during hard braking.

    Section 2 · 2.18 – Antilock Braking Systems (ABS) ↗PDF, 41 MB
  36. How does ABS change your normal braking capability?

    It does not increase or decrease it

    ABS is an addition to normal brakes and only acts when wheels are about to lock.

    Section 2 · 2.18 – Antilock Braking Systems (ABS) ↗PDF, 41 MB
  37. Does ABS shorten your stopping distance?

    Not necessarily, but it helps keep control during hard braking

    The main benefit of ABS is control, not a shorter stop.

    Section 2 · 2.18 – Antilock Braking Systems (ABS) ↗PDF, 41 MB
  38. What does the ABS electronic control unit do when sensors detect possible wheel lockup?

    Decreases brake pressure

    The ECU lowers brake pressure to avoid lockup while still giving maximum braking.

    Section 2 · 2.18.1 – How Antilock Braking Systems Work ↗PDF, 41 MB
  39. Truck tractors with air brakes built on or after what date must have ABS?

    March 1, 1997

    Air-braked truck tractors built on or after March 1, 1997 must have ABS.

    Section 2 · 2.18.2 – Vehicles Required to Have Antilock Braking Systems ↗PDF, 41 MB
  40. Other air brake vehicles such as trailers and converter dollies built on or after what date must have ABS?

    March 1, 1998

    Air-braked trucks, buses, trailers and dollies built on or after March 1, 1998 need ABS.

    Section 2 · 2.18.2 – Vehicles Required to Have Antilock Braking Systems ↗PDF, 41 MB
  41. Hydraulically braked trucks and buses of what GVWR built on or after March 1, 1999 must have ABS?

    10,000 lbs or more

    Hydraulic-brake trucks and buses rated 10,000 pounds or more built on or after March 1, 1999 need ABS.

    Section 2 · 2.18.2 – Vehicles Required to Have Antilock Braking Systems ↗PDF, 41 MB
  42. Where is the ABS malfunction lamp on tractors, trucks and buses?

    On the instrument panel, and it is yellow

    Power units have yellow ABS malfunction lamps on the instrument panel.

    Section 2 · 2.18.3 – How to Know If Your Vehicle Is Equipped with ABS ↗PDF, 41 MB
  43. Where is the ABS malfunction lamp on a trailer?

    On the left side, on the front or rear corner

    Trailers have yellow ABS lamps on the left side, either front or rear corner.

    Section 2 · 2.18.3 – How to Know If Your Vehicle Is Equipped with ABS ↗PDF, 41 MB
  44. On older systems, the ABS malfunction lamp could stay on until you are driving over what speed?

    5 mph

    On newer vehicles the lamp goes out right after the bulb check, on older ones it can stay on until over 5 mph.

    Section 2 · 2.18 – Antilock Braking Systems (ABS) ↗PDF, 41 MB
  45. The ABS lamp stays on after the bulb check. What may this mean?

    You may have lost ABS control

    A lamp that stays on, or comes on while moving, may mean ABS is not working.

    Section 2 · 2.18 – Antilock Braking Systems (ABS) ↗PDF, 41 MB
  46. How can you tell if an older towed unit has ABS?

    Look for the ECU and wheel speed sensor wires behind the brakes

    For towed units built before ABS was required, look under the vehicle for the ECU and sensor wires.

    Section 2 · 2.18 – Antilock Braking Systems (ABS) ↗PDF, 41 MB
  47. What can happen when your steering wheels lock up without ABS?

    You lose steering control

    Locked steering wheels mean no steering, and other locked wheels can cause skids or jackknifes.

    Section 2 · 2.18.4 – How ABS Helps You ↗PDF, 41 MB
  48. If only the tractor has ABS, what should you watch for while braking?

    The trailer swinging out, and let up on the brakes if it does

    With tractor ABS you keep steering control, but let up on the brakes if the trailer starts to swing out.

    Section 2 · 2.18.5 – ABS on the Tractor Only or Only on the Trailer ↗PDF, 41 MB
  49. Does having ABS on only one axle still help?

    Yes, it still gives you more control during braking

    ABS on only the tractor, only the trailer or even one axle still gives more control.

    Section 2 · 2.18.5 – ABS on the Tractor Only or Only on the Trailer ↗PDF, 41 MB
  50. How should you brake a vehicle that has ABS?

    As you always have, using only the force needed to stop safely

    Brake normally with ABS and use only the braking force needed.

    Section 2 · 2.18.6 – Braking with ABS ↗PDF, 41 MB
  51. When may you fully apply the brakes in an emergency stop with ABS?

    In a straight truck or combination with working ABS on all axles

    This is the only exception to normal braking with ABS.

    Section 2 · 2.18.6 – Braking with ABS ↗PDF, 41 MB
  52. If your ABS malfunctions, what should you do?

    Drive normally with your regular brakes and get it serviced soon

    You still have normal brakes when ABS fails, so drive normally and have the system fixed soon.

    Section 2 · 2.18.7 – Braking If ABS Is Not Working ↗PDF, 41 MB
  53. Which skids will ABS not prevent?

    Skids from spinning the drive wheels or going too fast in a turn

    ABS prevents brake-induced skids, not power or turning skids.

    Section 2 · 2.18.8 – Safety Reminders ↗PDF, 41 MB
  54. Will ABS make up for bad brakes or poor brake maintenance?

    No

    ABS is an add-on to normal brakes, not a replacement, and it cannot compensate for bad brakes.

    Section 2 · 2.18.8 – Safety Reminders ↗PDF, 41 MB
  55. What are the four causes of skids?

    Over-braking, over-steering, over-acceleration and driving too fast

    A skid happens whenever tires lose grip, and these are the four ways it happens.

    Section 2 · 2.19 – Skid Control and Recovery ↗PDF, 41 MB
  56. What is over-steering?

    Turning the wheels more sharply than the vehicle can turn

    Over-steering means asking the vehicle to turn more sharply than it can.

    Section 2 · 2.19 – Skid Control and Recovery ↗PDF, 41 MB
  57. Besides hard braking, what else can cause skids on a slippery road?

    Using the speed retarder

    Skids can also happen when the speed retarder is used on slippery roads.

    Section 2 · 2.19 – Skid Control and Recovery ↗PDF, 41 MB
  58. What causes most serious skids?

    Driving too fast for road conditions

    Drivers who adjust to conditions do not need to over-accelerate, over-brake or over-steer.

    Section 2 · 2.19 – Skid Control and Recovery ↗PDF, 41 MB
  59. What is by far the most common skid?

    The rear wheels losing traction from excessive braking or acceleration

    Drive-wheel skids, where the rear wheels lose traction, are the most common.

    Section 2 · 2.19.1 – Drive-wheel Skids ↗PDF, 41 MB
  60. How can you stop a skid caused by acceleration on ice or snow?

    Take your foot off the accelerator

    Easing off the accelerator stops it, and if it is very slippery push in the clutch.

    Section 2 · 2.19.1 – Drive-wheel Skids ↗PDF, 41 MB
  61. Why do the rear wheels slide sideways in a rear wheel braking skid?

    Locked wheels have less traction than rolling wheels

    With less traction, locked rear wheels slide sideways to catch up with the front wheels.

    Section 2 · 2.19.1 – Drive-wheel Skids ↗PDF, 41 MB
  62. In a vehicle towing a trailer, what can a drive-wheel skid cause?

    A sudden jackknife

    The trailer can push the towing vehicle sideways and jackknife it.

    Section 2 · 2.19.1 – Drive-wheel Skids ↗PDF, 41 MB
  63. What is the first step to correct a drive-wheel braking skid?

    Stop braking

    Releasing the brakes lets the rear wheels roll again and stop sliding.

    Section 2 · 2.19.2 – Correcting a Drive-wheel Braking Skid ↗PDF, 41 MB
  64. Why must you counter-steer as a skidding vehicle turns back on course?

    It tends to keep turning and can skid the opposite way

    Unless you quickly turn the wheel the other way, you may skid in the opposite direction.

    Section 2 · 2.19.2 – Correcting a Drive-wheel Braking Skid ↗PDF, 41 MB
  65. Where is the best place to practice skid recovery?

    On a large driving range or skid pad

    Skid recovery takes a lot of practice, best done on a driving range or skid pad.

    Section 2 · 2.19.2 – Correcting a Drive-wheel Braking Skid ↗PDF, 41 MB
  66. What happens in a front-wheel skid?

    The front end goes in a straight line no matter how you steer

    In a front-wheel skid, turning the wheel does not change the direction of the front end.

    Section 2 · 2.19.3 – Front-wheel Skids ↗PDF, 41 MB
  67. Besides speed, what can cause front-wheel skids?

    Lack of front tire tread and too little weight on the front axle

    Worn front tires and cargo loaded with too little weight on the front axle can cause them.

    Section 2 · 2.19.3 – Front-wheel Skids ↗PDF, 41 MB
  68. What is the only way to stop a front-wheel skid?

    Let the vehicle slow down

    Stop turning and braking so hard, and slow down as quickly as you can without skidding.

    Section 2 · 2.19.3 – Front-wheel Skids ↗PDF, 41 MB

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