Goodbye Brake Fluid? The Future of Braking
Over the past few decades, car manufacturers have eliminated several key automotive liquids thanks to electrification. Power steering fluid is gone, and electric vehicles have also done away with engine oil and automatic transmission fluid. Now, innovators are looking at another common fluid: brake fluid.
While some cars already have brake-by-wire systems, where the pedal is electronically linked to the master cylinder, Brembo and ZF are taking things further. They have created electromechanical brakes, which feature electrically actuated calipers instead of hydraulically actuated ones.
Photo credit: Brembo
With these systems, all four calipers can use an electromechanical mechanism to clamp the pads to the discs. Alternatively, only the rear calipers might be electromechanical, with the front hydraulics controlled by an electronically actuated master cylinder. This is a significant departure from the traditional hydraulic setup.
So, what advantages do electromechanical brakes offer?
One key benefit is faster actuation compared to hydraulic brake solenoids. This should result in more precise control of each wheel, allowing for automatic adjustments to account for weight transfer and varying surface friction. Computer algorithms could handle threshold braking in slippery conditions instead of relying entirely on driver skill.
Another benefit is the elimination of the heavy, pulsating anti-lock braking feedback that can startle drivers unaccustomed to ABS activation during panic stops. In addition, these calipers could eliminate brake pad drag, potentially reducing particulate emissions. They also integrate seamlessly with regenerative braking in electric vehicles.
Potential Benefits and Downsides
ZF claims their electromechanical calipers can reduce automatic emergency braking stopping distances from 62 mph by 29.5 feet compared to a standard hydraulic system. While we’ll need third-party validation to confirm this, the potential safety improvement is clear.
There are potential maintenance benefits too. Because electric calipers keep pads clear of the discs during regular operation, pad changes could become easier. There may be no need to retract the pistons, as retraction could be their default state.
Photo credit: ZF
Eliminating traditional brake lines also removes the possibility of corrosion and rust in the system. Furthermore, brake fluid flushes won’t be needed with electromechanical calipers, as there will be no fluid to flush.
So, what are the potential downsides?
One is unsprung weight. Adding an electric motor and mechanism to a caliper will likely make it heavier than a hydraulic setup. Another is packaging. These calipers look huge. They may require compromises in knuckle design and suspension arm placement to achieve sufficient steering angle.
Photo credit: ZF
There’s also the question of rodents. While rats rarely chew metal brake lines, they may be attracted to wiring. However, with contracts already in place, expect to see these systems appearing in production cars within the next few years.
Photo credit: ZF
