Podcast
Questions and Answers
What is a primary advantage of radial ply tyres during cornering?
What is a primary advantage of radial ply tyres during cornering?
- They have lower rolling resistance.
- The side walls are more flexible. (correct)
- They provide better wet traction.
- They have a longer tread life.
Which of the following is considered a disadvantage of radial ply tyres?
Which of the following is considered a disadvantage of radial ply tyres?
- Higher rolling resistance.
- Reduced susceptibility to punctures.
- Increased tread life.
- Poor transport handling due to low lateral stiffness. (correct)
What does the maximum adhesion coefficient occur at during braking?
What does the maximum adhesion coefficient occur at during braking?
- 20% slip
- 10% slip (correct)
- 40% slip
- 5% slip
In the context of the friction circle, what is the formula for the tyre/road interface force necessary for acceleration, braking, and cornering?
In the context of the friction circle, what is the formula for the tyre/road interface force necessary for acceleration, braking, and cornering?
Which characteristic of radial ply tyres contributes to cooler running temperatures?
Which characteristic of radial ply tyres contributes to cooler running temperatures?
What is indicated by the designation '215/65R15 95 H' of a tyre?
What is indicated by the designation '215/65R15 95 H' of a tyre?
What effect does under-inflation have on radial ply tyres?
What effect does under-inflation have on radial ply tyres?
Which factor does NOT affect the diameter of the friction circle?
Which factor does NOT affect the diameter of the friction circle?
What primarily causes a vehicle to resist motion when progressing up a gradient?
What primarily causes a vehicle to resist motion when progressing up a gradient?
In terms of vehicle performance, at what engine characteristic do maximum torque and power occur?
In terms of vehicle performance, at what engine characteristic do maximum torque and power occur?
What is the purpose of the drag coefficient in vehicle design?
What is the purpose of the drag coefficient in vehicle design?
Where is aerodynamic drag force typically represented in a vehicle?
Where is aerodynamic drag force typically represented in a vehicle?
Which of the following is NOT a type of tractive resistance?
Which of the following is NOT a type of tractive resistance?
At what coefficient of drag (CD) do the best passenger cars typically perform?
At what coefficient of drag (CD) do the best passenger cars typically perform?
What effect does gradient assistance have on a vehicle's motion?
What effect does gradient assistance have on a vehicle's motion?
What method is typically used to initially determine the distance of the center of pressure from the road level?
What method is typically used to initially determine the distance of the center of pressure from the road level?
What occurs if a vehicle continues to be driven with excessively deflated tyres?
What occurs if a vehicle continues to be driven with excessively deflated tyres?
How does tyre size affect rolling resistance?
How does tyre size affect rolling resistance?
What is the effect of under-inflation on rolling resistance?
What is the effect of under-inflation on rolling resistance?
What determines cornering resistance?
What determines cornering resistance?
Which components make up the total Tractive Resistance (TR)?
Which components make up the total Tractive Resistance (TR)?
What is one of the primary functions of a tyre?
What is one of the primary functions of a tyre?
What type of tyre construction is most common today?
What type of tyre construction is most common today?
Why must tyres maintain high adhesion coefficients with the road surface?
Why must tyres maintain high adhesion coefficients with the road surface?
What effect does air speed have on local pressure in a streamlined flow?
What effect does air speed have on local pressure in a streamlined flow?
What is the primary result of early air separation from a vehicle?
What is the primary result of early air separation from a vehicle?
What are the sources of rolling resistance (RR)?
What are the sources of rolling resistance (RR)?
How does the deformation of tyres affect energy during rolling?
How does the deformation of tyres affect energy during rolling?
What happens to the negative lift generated by aerodynamic flow over a vehicle?
What happens to the negative lift generated by aerodynamic flow over a vehicle?
What occurs if a tyre is under-inflated during high-speed driving?
What occurs if a tyre is under-inflated during high-speed driving?
Which of the following best describes aerodynamic drag force?
Which of the following best describes aerodynamic drag force?
What role does down force play in vehicle performance?
What role does down force play in vehicle performance?
What does N1 and N2 represent in the context of a vehicle on level ground?
What does N1 and N2 represent in the context of a vehicle on level ground?
Which force is represented by 'F' in the free body diagram of a vehicle accelerating on level ground?
Which force is represented by 'F' in the free body diagram of a vehicle accelerating on level ground?
In vehicle dynamics, what does the term Longitudinal Load Transfer Effect (LTE) refer to?
In vehicle dynamics, what does the term Longitudinal Load Transfer Effect (LTE) refer to?
How is the lateral load transfer effect during cornering presented mathematically?
How is the lateral load transfer effect during cornering presented mathematically?
What is the effect of aerodynamic drag on load transfer?
What is the effect of aerodynamic drag on load transfer?
What condition makes rear wheel drive cars more suitable for certain applications?
What condition makes rear wheel drive cars more suitable for certain applications?
What happens to individual loads when summing the individual loads for each wheel during a left-hand turn?
What happens to individual loads when summing the individual loads for each wheel during a left-hand turn?
What does the variable 'h' represent in the equations concerning lateral load transfer?
What does the variable 'h' represent in the equations concerning lateral load transfer?
Study Notes
Tractive Force & Engine Characteristics
- Tractive Force (TE) or Tractive Effort is the force that propels a vehicle
- For conventional internal combustion engines, vehicle speed (v) is determined by engine speed (Ne), gear ratio (ng), final drive ratio (nd), and effective rolling radius of the tire (r)
Tractive Resistances (TR)
- Three fundamental parameters contribute to a vehicle's resistance to motion: gradient resistance (GR), aerodynamic drag (D), and rolling resistance (RR).
- Gradient Resistance (GR) is the proportion of a vehicle's weight acting down a gradient, represented by the mgsinθ component.
- Aerodynamic Resistance or Drag Force (D) is a measure of the resistance of a vehicle to progress through air.
- Rolling Resistance (RR) is the force that must be overcome to cause the vehicle to move at constant speed over a level surface.
- Rolling resistance arises from deformation of the tires during rolling and friction in the mechanical driveline components.
Aerodynamic Resistance (D)
- Aerodynamic drag coefficient (CD) is an important vehicle design parameter affecting efficiency and fuel economy.
- Best passenger cars have a CD of around 0.3.
Rolling Resistance (RR)
- Rolling tires undergo continuous cyclical deformation, causing energy loss through hysteresis.
- Tyre inflation pressure influences rolling resistance.
Tractive Resistances and Performance
- Total Tractive Resistance (TR) is the net sum of rolling resistance, aerodynamic drag, and gradient resistance.
- The relationship between TE and TR varies based on vehicle speed, engine output, and other factors.
Tyre Properties and Performance
- Tires transmit the drivetrain torque to the road, enabling vehicle movement.
- Tires contribute to braking and safe maneuvering.
- Tyre/road interface adhesion coefficient (μ) is crucial for traction, braking, and cornering stability.
Tyre Construction
- Two types of tyre construction: radial ply (most common) and cross (bias) ply.
- Radial ply tires offer advantages such as longer tread life, cooler running, lower rolling resistance, and improved comfort.
Tyre Designation
- Tyre designations provide information about the tyre size, aspect ratio, construction (radial or bias), rim diameter, and load/speed rating.
The Friction Circle
- The Friction Circle represents the maximum force a tire can transmit to the road surface.
- The diameter of the Friction Circle is determined by the product of the vertical load (N) and the tyre/road interface friction coefficient (μ).
Rigid Body Load Transfer Effects
- Axle loads change due to acceleration/deceleration and cornering.
- Longitudinal Load Transfer (LTE) occurs due to acceleration/deceleration and aerodynamic drag.
- Lateral Load Transfer (LTE) occurs due to cornering forces.
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Description
Test your knowledge on tractive force and the characteristics of internal combustion engines. This quiz explores the dynamics of vehicle motion, including tractive efforts and resistances. Assess your understanding of the factors that influence a vehicle’s performance on the road.
