Objectives: (Day 5)

Students will understand three types of traction

Students will understand driving on dangerous road surface conditionsangerous road surface conditions

Students will understand traction loss raction loss considerationsconsiderations

Students will understand driving off-road and ff-road and recoveryrecovery

Bell Ringer #5 Write a half a page red to red on the

below statement. Save these to be turn in on test day. 10% of your grade

It is sometimes said that borrowing money from a friend can harm or damage the friendship. Do you agree? Why or why not? Use reasons and specific examples to explain your answer.

Reminder1.1. Bring paper/pen/pencil and notebookBring paper/pen/pencil and notebook

2.2. Electronics are for instructional use with permission Electronics are for instructional use with permission

3.3. Don’t forget to do daily quizzes on QUIA.COMDon’t forget to do daily quizzes on QUIA.COM

4.4. No Excuses why you don’t take Quizzes 1-6 No Excuses why you don’t take Quizzes 1-6

before test day!! (Quizzes are worth 30% of grade)before test day!! (Quizzes are worth 30% of grade)5.5. Attendance is MANDATORY!! (NO SLEEPING in class)Attendance is MANDATORY!! (NO SLEEPING in class)

6.6. All notes can be found on Harrisonburg’s staff website:All notes can be found on Harrisonburg’s staff website:

http://staff.harrisonburg.k12.va.us/~tbutler/http://staff.harrisonburg.k12.va.us/~tbutler/

7.7. If you are NOT taking notes in class, please be quiet and If you are NOT taking notes in class, please be quiet and ask to use the restroom at the end of class.ask to use the restroom at the end of class.

Traction Loss Concerns

Traction

Traction is the grip between the tires and the road surface

Traction allows a vehicle to start, stop, and/or change direction.

Traction can be lost to the front tires or the rear tires.

If the front and rear tires are actually leading the vehicle (sideways traction loss).

Three types of traction influence the control/or movement of a motor vehicle: static, rolling (dynamic), and sliding.

Traction

Static Traction

A stationary vehicle parked on a flat surface with its brakes set is an example of static traction.

It has the greatest resistance to movement.

Rolling Traction

There is more traction between a rolling wheel and the road than there is between a sliding wheel and the road.

This is why a driver needs to keep the wheels rolling and not lock the brakes when trying to steer or stop a vehicle that is sliding.

Sliding Traction

There is greater traction between a stationary wheel and the road than there is between a sliding wheel and the road.

Sliding traction does not grip the road.

Dangerous Road Surface ConditionsDangerous Road Surface Conditions

• Ice, snow, or frostIce, snow, or frost• Wet--particularly the first 15 minutes of Wet--particularly the first 15 minutes of

rain after a long dry period when oil rain after a long dry period when oil and rubber particles have collected on and rubber particles have collected on the road surface and mix with waterthe road surface and mix with water

• Heavy rain or standing water Heavy rain or standing water • Mud near farm entrances, construction Mud near farm entrances, construction

sites, and truck crossingssites, and truck crossings

IceIce

RainRain

SnowSnow

MudMud

Dangerous Road Surface ConditionsDangerous Road Surface Conditions

• Wet leavesWet leaves

• Broken or uneven road surfaceBroken or uneven road surface

• Sand or gravel frequently found on curves in Sand or gravel frequently found on curves in

rural areasrural areasOn improperly banked or flat On improperly banked or flat curves, traction is more likely curves, traction is more likely to be lost when roads are wet to be lost when roads are wet or slippery at slow speeds, or or slippery at slow speeds, or when dry at higher speeds when dry at higher speeds

NEGATIVE BANKNEGATIVE BANK

Causes ofCauses of Traction LossTraction Loss

Brakes unevenly adjusted

Brakes pulling in one direction or the other can cause

a skid--as can wheels out of alignment when brakes

are applied

Tires with unevenly worn tread

- The size of the front and rear tires do not matched

- The tread depth or tire type of the front and rear tires are different

Condition of the VehicleCondition of the Vehicle

Different tire pressure on opposite sides of

the vehicle has a similar effect to uneven

brake adjustment since one tire will drag

more than others

Causes ofCauses of Traction LossTraction Loss

Sudden steering actions on a slippery surface, or abrupt or sudden changes in vehicle speed

Panic stop or applying the brakes too hard on a hill, curve or slippery surface

Suddenly engaging the clutch on a slippery surface

Most driver-induced skids are caused by:

excessive speed

coupled with excessive steering input

or improper braking when turning

Loss of traction also occurs with these driver’s actions at normal speeds on ice/snow or on roadways covered by sand, gravel, or water

Driver Actions that may cause loss of traction Driver Actions that may cause loss of traction

• Sudden shifts of vehicle weight causes traction loss

- Left, Right, Forward, or Backward• Simultaneous steering, braking and/or acceleration

creates sudden shifts in vehicle balance

• Traction loss compounds crash consequences

Traction Loss ConsiderationsTraction Loss Considerations

LIFTSLIFTS

DROPSDROPS

Weight Moves to the Front of the Car Causing Weight Moves to the Front of the Car Causing

– a noticeable drop of the hood

– a noticeable rise of the rear deck

– forward movement of driver and passengers

Traction Loss ConsiderationsTraction Loss Considerations

When When BrakesBrakes are Applied Too Hard or Quickly are Applied Too Hard or Quickly

Direction of Travel

Force or Weight Movement

Rear Rear LIFTSLIFTS

Front DROPSFront DROPS

Weight Moves to the Rear of the Car CausingWeight Moves to the Rear of the Car Causing

– a noticeable rise of the hood

– a noticeable drop of the rear deck

– rearward movement of driver and passengers

Traction Loss Consideration

When When AccelerationAcceleration is Applied Too Hard or Quickly is Applied Too Hard or Quickly

Direction of Travel

Front LIFTSFront LIFTS

Force or Weight Movement

Rear Rear DROPSDROPS

Weight Moves to the Opposite Side of the CarWeight Moves to the Opposite Side of the Car Weight Movement Causes: Weight Movement Causes:

– a noticeable drop and tilt of the hood

– a noticeable rise and tilt of the rear deck

– driver and passenger movement towards the car’s corner

Traction Loss Consideration

When When SteeringSteering is Applied Too Hard or Quickly is Applied Too Hard or Quickly

Force or Weight

Movement Front DROPSFront DROPS

Rear Rear LIFTSLIFTS

Direction of TravelDirection of Travel

Traction between the tires and the road does not remain constant.

For example, sand, gravel, or water on the road decreases the level of traction.

As speed increases, traction between the tires and the road decreases. With decreased traction, the possibility of skidding or sliding increases.

Traction

The driver must recognize which part of the vehicle is losing traction in order to activate the technology needed to correct the problem.

Recognize Traction Loss

Traction Loss to Front Tires

If A Vehicle Keeps Moving Straight Ahead in Spite of Steering Efforts To the Contrary, It Means Front Traction Has Been Lost

The Technical Term is Called “Understeer”

Actual Path Actual Path of Travelof Travel

Intended Path Intended Path of Travelof Travel

front tires front tires SLIDESLIDE

rear tires rear tires PUSHPUSH

•The Driver Will First Visually Identify Unusual Forward Sliding Movement Caused by the Vehicle’s Weight Pushing the Front Wheels Straight Ahead Regardless of Any Steering Input

To Correct Front Traction LossTargeted Path of TravelTargeted Path of Travel

Lift Eyes to Lift Eyes to TargetedTargeted Path of TravelPath of Travel

Intended Path of TravelIntended Path of Travel

Actual Path Actual Path of Travelof Travel

• Direct Vision to Targeted Path of TravelDirect Vision to Targeted Path of Travel

• Activate ABS, if Vehicle is EquippedActivate ABS, if Vehicle is Equipped– Ease off Conventional Brake System– Reestablish Rolling Traction

• Ease off Steering InputsEase off Steering Inputs– Abrupt Steering Can Create Traction Loss– Allows Tire Tread to Point Toward Path of Travel

• Jab/Stab Brake to Move Weight Forward if ABS is not Jab/Stab Brake to Move Weight Forward if ABS is not Available Available (ABS performs this function automatically)(ABS performs this function automatically)

Traction Loss to Rear Tires

• Identified by driver when front of vehicle moves to the left or Identified by driver when front of vehicle moves to the left or right of travel path without steering input in that directionright of travel path without steering input in that direction

• Technical term is “Technical term is “Oversteer”Oversteer”

Intended Path of TravelIntended Path of Travel Actual Path Actual Path of Travelof Travel

• Vehicle’s Weight Tends to Push Rear Vehicle’s Weight Tends to Push Rear Wheels Left or Right Without Steering Wheels Left or Right Without Steering InputInput

• Vehicle Begins To YawVehicle Begins To Yaw

front tires front tires ROLLROLL

rear tires rear tires SLIDESLIDE

• Direct Vision to Targeted Path of Direct Vision to Targeted Path of

TravelTravel

Rear Traction Loss Correction

On Targeted Path

On Targeted Path

Off Targeted Off Targeted PathPath

• Steer Toward Targeted Path of TravelSteer Toward Targeted Path of Travel

• Adjust Steering Input as Needed to Maintain Targeted Path of Adjust Steering Input as Needed to Maintain Targeted Path of Travel Travel

• Apply Light Progressive Acceleration (2 mph is goal) to Move Apply Light Progressive Acceleration (2 mph is goal) to Move the Weight to the Rear. (The Traction Control System will the Weight to the Rear. (The Traction Control System will adjust the speed and brakes automatically when activated)adjust the speed and brakes automatically when activated)

• Activate Traction Control Activate Traction Control System, if Equipped:System, if Equipped:

– Ease off brake or accelerator

– Reestablish rolling traction

Intended Intended Path of Path of TravelTravel

Rear Tire MovementRear Tire Movement

Off-Road RecoveryOff-Road Recovery• Do not panic and steer too abruptlyDo not panic and steer too abruptly

• Ease off accelerator Ease off accelerator

• DO NOT BRAKEDO NOT BRAKE

• Get both wheels off the pavementGet both wheels off the pavement

• Steer the vehicle parallel to the roadwaySteer the vehicle parallel to the roadway

• If clear, ease back on to the roadway one wheel at If clear, ease back on to the roadway one wheel at a timea time

• Limit steering inputs to less than 1/8 of a turn of Limit steering inputs to less than 1/8 of a turn of the wheel the wheel

• Use even less input when the edge of road is highUse even less input when the edge of road is high

• Target the center of the adjacent lane to avoid a Target the center of the adjacent lane to avoid a “Slingshot” maneuver into oncoming traffic “Slingshot” maneuver into oncoming traffic

Class Work

In your driver’s education book, read pages 252-256.

Do Lesson review 1 questions (1+2) on page 256.

Save these to be turned in with your test!

THE END!