CABLES ACTUATED THE EARLIEST CAR BRAKES. Indeed Ford continued with them until 1939. As you might imagine, maintaining equal actuation at all four wheels was a non-trivial matter.
Replacing cables with hydraulic lines solved this balancing act. Malcolm Loughhead (who later changed spelling to Lockheed—yes, that Lockheed—had patented the idea in 1917. According to Wikipedia, Fred Duesenberg used Lockheed Corporation hydraulic brakes on his 1914 racing cars and his car company, Duesenberg, was the first to use the technology on the Duesenberg Model A in 1921…. The technology was carried forward in automotive use and eventually led to the introduction of the self-energizing hydraulic drum brake system (Edward Bishop Boughton, London England, June 28, 1927) which is still in use today.”
Variations on a Theme. There have been plenty of changes since the 1920s. Brake boosters reduced pedal pressure, these “power brakes” vastly overdone initially in the 1940s and 1950s. Safety considerations of the 1960s brought about redundancy of split braking circuits.
Anti-lock concepts had originally entered aviation practice in the 1950s. By the early 1970s, ABS appeared in cars, though it took a couple decades to become ubiquitous.
A New Theme: Braking by Electricity. By the turn of the century (our latest turn), parking brakes have had electromechanical actuation. Also, braking by both electrohydraulic and electromechanical means have been evolving.
Brembo’s Sensify. Hans Greimel writes in Automotive News, September 19, 2023, that “Brembo wants its new artificial-intelligence-based braking system, Sensify, to set a new industry standard just as antilock braking did decades ago”
“Sensify,” Greimel reports, “combines Brembo’s portfolio of calipers, discs and friction materials with digital technology and artificial intelligence to create a flexible network that includes software, predictive algorithms and data management to control the brake system digitally.”
He continues, “Today’s brake systems use hydraulic calipers that apply the same force to each wheel. When a wheel loses grip, the ABS opens that caliper to regain grip and then braking is resumed. In Sensify, two control units, one for the front axle and one for the real axle, apply the desired braking force to each individual wheel. The braking process uses electromechanical actuators that have a faster reaction time than traditional hydraulic systems.”
The key here is “electromechanical,” akin to today’s parking-brake actuation.
Greimel recounts, “Brembo said the system can be used in a dry setup without hydraulic fluid for a completely electric system in anything from compact cars to large sedans and SUVs. It can also leverage a hydraulic system connected to the electronic backbone for added oomph in sports cars. And it can be deployed in vans, trucks and commercial vehicles, Brembo said.”
EV Oriented. Greimel says, “Brembo predicts the new system will have special appeal in the age of electric vehicles because Sensify will make it easier for carmakers to differentiate the ride and handling of their vehicles through a software-controlled braking system that can be tailored to a brand’s persona.”
Today’s hybrids and EVs already employ regenerative braking, using the electric motors’ ability to feed retardation energy back into the battery pack. Indeed, several have adjustable regen giving single-pedal operation in many easy-braking conditions.
Teething Problems, Or Conceptual Flaws? All of this new technology has not been without problems: Tesla has had rather a few recalls involving its brake system: one in 2017; another involving “phantom braking,” and yet another affecting virtually every Tesla sold in China. Honda Civic websites have had plenty of discussion about its conceptually simpler electronic parking brake.
Gee, I wonder if early hydraulic systems leaked like sieves? And how did engineers resolve the “power brake” lack of feel? I do recall controversy about whether locked wheels were better than ABS in snow or gravel (generally, they weren’t). Technology is an evolving thing. ds
© Dennis Simanaitis, SimanaitisSays.com, 2023