How much (roughly) brake torque can be produced by a regular car

In summary, the conversation revolves around determining the brake torque of a regular car for a simplified vehicle model. The maximum braking will occur just before the tyre locks up, which is calculated by multiplying the static coefficient of friction and load on the tyre. The suggestion is made to use legal maximum braking distances and typical mass of the vehicle to estimate the braking torque. It is also suggested to model the maximum braking acceleration of the car, which is usually around -1.0g for most cars. Some high-performance cars can reach up to -1.3g. It is important to consider anti-lock brakes and not overheat the brakes. As an example, a 2200kg SUV is capable of -3000Nm brake torque.
  • #1
pfk
4
0
Hi everyone! I am new to the forum but you have helped me many times in the past.

I need your opinion about how much (roughly) brake torque can be produced by a regular car.

I am developing a simplified vehicle model and I don't know how much torque to apply when the vehicle slows down. I apply 200-300Nm for a "soft" deceleration, almost 1000Nm for "medium" and 2000Nm for hard one.

Do those values make sense to you?

Thank you for your time!
 
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  • #2
The question as posed makes little sense.

It's a function of tyre grip, as all brakes as designed can lock the wheels up. Disregarding the complexities of pneumatic tyres (assuming that standard friction equations are valid).

Maximum braking will occur just before the tyre locks up. This is:
static coefficient of friction * load on tyre.

F = mu*Fn

The maximum torque applied:
force * the distance to the centre of the wheel.

T=Fd
 
  • #3
Sorry about my question. I am not looking for a particular equation, I am looking for some empirical data. My model is very simplified, so I’m not taking into consideration the dynamics of the wheels.

I would like to know what is the brake capability [brake torque Nm] of an average vehicle.
 
  • #4
pfk said:
My model is very simplified, so I’m not taking into consideration the dynamics of the wheels.

You could start by taking the legal maximum braking distances in your country that are required for vehicle safety checks etc, and usually published in books on learning to drive. Use those figures and a typical mass of the vehicle to estimate the braking torque
 
  • #5
Great idea! Thank you!
 
  • #6
You could just simply model the maximum braking acceleration the car is capable of. I think most cars as a general rule are capable of about -1.0g of braking acceleration (60-0mph in 110 feet); high-performance cars even more, maybe 1.3g (60-0mph in 90 feet).

Braking curves for most cars are usually pretty flat too (pretty constant acceleration), as long as they have anti-lock brakes and don't overheat the brakes.
 
  • #7
Mech_Engineer said:
You could just simply model the maximum braking acceleration the car is capable of. I think most cars as a general rule are capable of about -1.0g of braking acceleration (60-0mph in 110 feet); high-performance cars even more, maybe 1.3g (60-0mph in 90 feet).

Braking curves for most cars are usually pretty flat too (pretty constant acceleration), as long as they have anti-lock brakes and don't overheat the brakes.


Thank you!

I found that the 2200kg SUV that I approach is capable of -3000Nm brake torque. So, I multiply the brake pedal position [0,..,1] with the -3000 and the result is one of the 3 inputs that my mode has.
 

FAQ: How much (roughly) brake torque can be produced by a regular car

1. How is brake torque measured on a regular car?

Brake torque is typically measured in pound-feet (lb-ft) or Newton-meters (Nm) and is calculated by multiplying the force applied to the brake pedal by the distance from the center of the brake rotor to the point where the force is applied.

2. What factors affect the amount of brake torque a regular car can produce?

The size and weight of the vehicle, the type of braking system (e.g. disc brakes vs. drum brakes), and the condition of the brake components (e.g. brake pads, rotors) can all affect the amount of brake torque a regular car can produce.

3. What is the typical range of brake torque for a regular car?

The typical range of brake torque for a regular car is between 200-800 lb-ft or 270-1080 Nm. However, this can vary depending on the factors mentioned in question 2.

4. Can a regular car produce more brake torque than the recommended amount?

Yes, a regular car can produce more brake torque than the recommended amount. However, this can put added strain on the braking system and potentially cause damage or decrease the lifespan of the components.

5. How can I increase the brake torque on my regular car?

There are a few ways to increase the brake torque on a regular car. Upgrading to high-performance brake pads and rotors, properly maintaining the braking system, and increasing the force applied to the brake pedal can all help increase brake torque. However, it is important to note that increasing brake torque should be done carefully and with caution to avoid damaging the vehicle's braking system.

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