straight from the pirate- you guys read and maybe will clear up some things.. read it more than once. i think the conclusions are a little bias based on poorly designed OEM systems, but the physics don't lie, pinion brakes can and will create more braking when used properly.
OK, so, moving rig has kinetic energy, kinetic energy must be turned into heat, rotors must absorb said heat. Big deal, so what?
Well, the equations that follow are used to calculate the temperature increase in the rotor for a given kinetic energy. Remembering that kinetic energy depends on weight and speed, they also explain in incontrovertible terms (big word – means you can’t bloody argue with me about it!) exactly why “pinion brakesâ€, flat out suck, and why Patooyee’s rotors keep trying to melt off ! Remember – to add insult to injury “pinion brakes†are often used on Rockwell-axled rigs – which are big and heavy, and weight is a multiplying factor in the equation for Kinetic energy.
[As an aside – the previous discussion on brake torque also explains why some feel that pinion brakes work well “at slow speedâ€. It’s because the rotor is placed before the axle differential, meaning the pinion brake’s brake torque is calculated as above and then multiplied by a factor equal to the axle ratio. This means, even with small callipers and rotors, they can develop tremendous brake torque. But – remember what we said about the requirements of a braking system – it must also have sufficient thermal capacity – and they simply do not. In fact, they’re dangerously inadequate in this regard!]
