6 replies to this topic

[Tenmantaylor]

What contributes more to brake temperature? Time spent on the brakes or pressure? Or is it a combination? A few calculations I found mentioned only time spent on the brakes and not pressure being a contributor?

[saudoso]

I guess they are assuming maximum braking power.

You need to consider speed, braking force (pedal pressure) and time spent braking.

Temperature will rise untill the temp difference between brake and environment is big enough to dissipate all the converted kinetic energy.

If you just touch the brakes the temperature will stabilize at a pretty lower value than if you really step on it (at a given fixed speef).

Edited by saudoso, 17 October 2017 - 07:01.

[GreenMachine]

It is the work done by the brakes, is it not?   Pressure, time, delta vee, mass ... but mainly the last three, pressure is a means.

[saudoso]

Pressure gives the force in work = FxD. Half the pressure, half the work.

[blkirk]

Pressure gives the force in work = FxD. Half the pressure, half the work.

 

Distance in the work is of course speed x time.  So pressure X speed X time is proportional to heat in.  Speed x temp will be proportional to heat lost to cooling.

[Lee Nicolle]

Brake temp, generally semi bad on a road vehicle and generally essential on race pads.

Gently riding brakes generally produces a lot of heat, a single brisk stop produces less. 

Different pad material seems to produce different rotor temps as well.  A pad I used to use in used cars was nice to drive around town but when asked to work hard  saw  the brake rotors shuddering badly. On what was then my work ute I spent more money and put in a premium pad [about 4 times more expensive]  and most of the shuddering went away. And ofcourse once rotors have hard spots they usually never recover.

What scares me most is on long down hill runs most people continually ride the brakes and when they get to the bottom and need to stop they struggle to stop as the material has faded,, let alone fluid temerature.

In Adelaide our hills freeway has such a downhill grade and far too many accidents happen. Trucks get the media attention but there will be a huge bus crash there one day. I have seen commuter buses on several occasions with clouds of smoke pouring from the brakes. With a 100 people on board! Plus caravanners, even worse. Saw one go through a red light, luckily no cars were coming!

Yet I can drive down there with 2 tonne of trailer and hardly use the brakes. With auto towcars. Just simply use a lower gear or two,, or three!

[Fat Boy]

Brake temps are an energy balance. Energy in = Energy out.