Photos by Justin Pritchard and courtesy manufacturers
Brakes are one of the least-glamorous and most important parts of your ride. Though it’s largely acceleration figures and horsepower numbers and torque output that are touted when someone boasts about their ride, it’s ultimately the brakes that keep all of the above in check. Nobody spouts stopping distance, rotor diameters or advanced anti-lock functionalities when bragging about their machine, but you can bet that when it comes time to stop in a hurry, that often-overlooked braking system will suddenly become the vehicle’s most important feature.
Used to be that cars had drum brakes on all four wheels. The premise? A steel drum rotated with the wheels around a simple mechanical or hydraulic system, fixed in place, that pressed brake shoes into the inside of the rotating drum assembly when the brakes were applied, creating friction, heat, and deceleration.
Then, disc brakes came into action. The friction-based principle was the same, though stopping power was instead generated by pads clamping over a rotating disc to provide stopping power instead. Most cars now use a four-wheel disc brake system, though some use discs up front and drums in the rear, mostly to save money.
|Brake Tech 101. Click image to enlarge|
Somewhere along the way, in the seventies or so, the elemental Anti-Lock Braking System (ABS) came into play, effectively allowing the brakes to be pulsed at a high frequency during emergency stops. Compensating for a driver’s natural tendency to simultaneously smash the brake pedal and rip the steering to one side when faced with a panic situation, rather than to consider and execute threshold braking to maintain front-wheel traction, ABS allowed the vehicle to remain steerable during a panic stop, rather than locking its wheels and plowing head-on into the object the driver was trying to avoid. Virtually every new car today has ABS.
But things have advanced considerably since the seventies.
Electronic Brakeforce Distribution (EBD) was one example of how. Old ABS systems monitored the slippage at a single wheel and pulsed each of the brakes with the same frequency. This was effective for its time, but primitive in execution. With EBD, the anti-lock functionality works on a wheel-by-wheel basis instead, monitoring traction at each wheel and responding with a wheel-specific pulse pattern. It’s sort of like having a separate ABS system on each wheel. Result? Straighter stops on split-traction surfaces, more predictable stops if the vehicle is loaded unevenly, and overall, less drama and fuss when emergency stopping when traction varies between the wheels.
ABS testing on ice, electronic stability control testing. Click image to enlarge
Brake Assist, or Panic Brake Assist has become popular, too, since launched by Mercedes in the early nineties. The gist is simple: even if you need to stop quickly, you probably don’t want your double-double to wind up all over the windshield, or the stuff in your back seat to whack you in the back of the head, so you’ll err on the side of caution when applying the brakes, giving the pedal lighter pressure than required to maintain your comfort level. Then, as you get too close to the hazard, realizing you need more braking force, you apply more pedal to your (already hot) brakes, a little too late, and have a bit of a whoopsie.