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 Review of Weight Transfer When we apply the braking force, weight transfer happens to the front. Therefore, front vertical force gets heavier, and rear vertical force gets lighter. Brake force is the horizontal force proportional to the vertical reaction force. The proportional constant is tire friction coefficient μ. The role of rear brake is very important for vehicle stability. Rear brake force should always not only keep its quantity not to provoke wheel locking but also keep its maximum quantity just below the force level causing the rear wheel locked up. That is the way to use the brake system with the maximum efficiency.  Optimum Brake force distribution – Normalized Force The picture above shows an optimum brake force distribution curve. Vertical axis represents normalized braking force of rear wheel F nr , and horizontal axis represents the normalized braking force of front wheel F nf .  Here, the normalized force means its value is dimensionless. The two normal...

  measuring the height of vehicle CG(center of gravity) 1. measuring CG in the longitudinal axis. From the moment equilibrium about y axis passing through the center of tire-road contact patch, From the moment equilibrium about  y axis passing through the center of tire-road contact patch, 2. measuring CG in the inclined vehicle. Hypotenuse of yellow rectangular triangle is (h-R). Therefore, opposite of triangle is (h-R)sinθ. Sum of vertical forces should be zero. Sum of the moment about lateral axis passing through the CG should be zero. 2. measuring CG in the inclined vehicle. Equation of h above can be simplified as follow.

 Contents Effective Rolling Radius and Longitudinal wheel Speed Quiz : what happens in the effective radius in braking and acceleration If any change in radius, it it longer or shorter in braking Tyre longitudinal slip in acceleration Tyre longitudinal slip in braking Conclusion Effective Rolling Radius and Wheel Speed When a car stops, tire is loaded vertically by its weight. At that time, vertical wheel radius to the road surface is R L and unloaded circumferential radius is R u . When a car starts on straight and level road, the longitudinal speed of wheel center Vx is neither ωR L nor ωR U . Real longitudinal speed of tire center will be somewhere between ωR L and ωRu. You can get the effective rolling radius if you count the number of wheel turns and measure the distance at a given constant speed. The effective rolling radius can be described as the ratio of  the vehicle speed to the angular velocity of wheel as shown in the equation above. Effective Radius Re can be e...

CG effect on braking & acceleration Summary  Quiz : Which brake should keep its function for the entire braking process if you choose only one brake among 4? Why does a car tend to rotate at braking and accelation? What are the effects of CG location on braking and acceleration Effects of vertical location Effects of horizontal location Where is the best CG location of perfect car Figuring out the answer to this quiz, you will have a chance to think about the important effects of CG related to its height and horizontal location on braking and acceleration. And we will have a discussion on why a car tend to rotate at braking and acceleration. Then, I will explain what are the effects of CG location on braking and acceleration. Effects of vertical location, effects of horizontal location. Finally, I will explain what is the best CG location of perfect car. Review I picked up this picture from my previous article. As I explained, front tire braking force and vertical reaction forc...