Your vehicle’s brakes work best when they’re dry, but Mother Nature doesn’t always align her schedule with your commute. Some automakers have introduced technologies to improve wet-weather braking, including Cadillac’s Auto Dry Brakes.
“When you have dry brakes, you have your optimum braking performance,” says Elizabeth Pilibosian, vehicle chief engineer for the Cadillac SRX, which uses the system.
“The system is preparing the driver for a potential braking manoeuvre and optimizing their braking performance and feel.”
Disc brakes use heavy round metal discs, also called rotors, which fit behind the wheels and turn with them. A caliper containing brake pads fits over top of it. When you press the brake pedal, the caliper squeezes the pads against the spinning rotor. The resulting friction stops the vehicle.
The Auto Dry system periodically touches the brake pads to the rotors on all four wheels, acting like a squeegee to remove excess water. It works only when the vehicle is travelling more than 32 km/h, the driver’s foot is on the throttle, and the wipers are activated. If all these conditions are met, the system touches the pads to the rotors every six kilometres.
“The driver cannot feel it, it’s such a gentle touch,” Pilibosian says. “It’s not drying them completely, just taking the (water) droplets off. It dries the pads as well.”
The pads touch lightly enough that there is no perceivable brake wear, Pilibosian says. While a vehicle without the system will still be able to stop, the Auto Dry Brakes improve performance.
“When you’re driving in a wet environment (without the system), your brakes may feel less responsive,” she says.
“You may have to press harder to get the responsiveness that you need or desire. When you have a dry rotor, your braking performance and responsiveness is better.”
Should the driver have to use the brakes, the system automatically resets itself, wiping the brakes again once six kilometres have passed. It works whether the car is going in a straight line or on a curve.
The system is simply an algorithm programmed into the car’s existing stability control system and does not add any extra components.
“We’re using a computer that knows the wipers are on, that you’re on the throttle, that you’re above a certain speed, and it takes all of those attributes, gathers them up and says ‘all of these things are in place, this algorithm can be implemented,’” Pilibosian says.
“We haven’t added any computers. You’re just using the data the car already has.”