| Re: [GMCnet] Trip Repport (in segments) [message #343170] |
Tue, 07 May 2019 15:58  |
emerystora
Messages: 4442
Registered: January 2004
Karma:
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Senior Member |
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Ken
I don’t think I anyone is expecting 4 tires to apply more retarding force to the road than can 6 tires.
If one is braking properly in he same distance, they should use exactly the same amount of retarding force. We should not be concerned with the maximum retarding force.
As long as there is adequate retarding force to quickly stop the vehicle that is our concern. The problem is that the tires might slip so as to apply less stopping force.
As long as the tires don’t slip there is no problem. .
The no slip condition is
𝑣=𝑟𝜔
v
=
r
ω
, where 𝑣
v
is the linear speed of the centre of the tire/wheel/car, 𝑟
r
is the radius of the wheel and 𝜔
ω
the angular speed of the wheel, will result in the frictional force between the tire and the road at the point of contact being zero on a horizontal road.
When the engine tries to make the wheel rotate faster there is the potential of relative movement between the tire and the road at the point of contact so a static frictional force acts on the tire which increases the linear speed (and angular speed) of the tire/wheel/car.
This is the static frictional force acting in the forward direction.
When the brakes try and slow the rotation of the wheel down again a static frictional force acts on the tire which reduces the linear speed (and angular speed) of the tire/wheel/car.
That static frictional force acts in the opposite direction to the motion of the car.
So the static frictional force between the tire and the car always tries to make sure there is no relative movement between the tire and the road at the point of contact.
If there is slipping between the tire and the road (either during acceleration or braking) then kinetic friction takes over to try and reduce the relative motion between the tire and the road at the point of contact.
So in simple terms your have an number of forces acting on the car including the weight of the car, the normal reaction of the road on the car, the frictional forces between the tires of the car and the road and the frictional forces between the air and the car.
As long as there is adequate friction between the tire and the road so that the tires don’t slip it does’t matter if there are two tires, 4 tires, or more.
That is why I tried panic stops in my testing to make sure my tires weren’t slipping.
I really don’t care to get into any arguments with anyone about my use of whatever braking system I desire or how it compares to whatever anyone else wishes to use.
All I care about is whether it works for me. If it does then I am satisfied. If it didn’t then I would make further modifications until it did. If your system works for you that is all that matters but please don’t anyone tell me that I am wrong because of what I choose to use. This is beginning to sound like the tire wars of old. Do what you want to do and let me do what I want to do.
Emery Stora
77 Kingsley
Frederick, CO
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