Draining the Fluid from Braking

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Like so much of the world in which it exists, the automotive industry is accelerating through changes which will have profound impacts on both the consumers who use these vehicles, and the organizations involved in their production.

Government legislation along with societal pressure is bringing about changes to the materials used in the manufacturing of a vehicle and its components as well as in the type of vehicles produced. Vehicles today, and more so going forward, must be more environmentally responsible while being more automatic in operation.

All aspects of a vehicle’s infrastructure are open to consideration, modification and modernization. Integral to so many of the changes occurring to vehicles is the means by which they decelerate and stop.

For more than 100 years, hydraulic-activated braking systems provided the primary means of slowing and stopping everything from motorcycles to trucks. (The largest trucks swap out hydraulic-liquid [brake fluid] for a gaseous fluid – air.)

These systems have vastly improved since the 1918 introduction of hydraulic brakes, but the basic design has not changed drastically. Basic operation begins with a brake pedal’s activation pressurizing fluid in a master cylinder; the pressure on the brake fluid spreads to the brake components either on an axle for multiple wheels or components at each individual wheel. This activates components like caliper pistons to “grab” a brake rotor, thus slowing, and if desired, stopping, the vehicle.

Power assistance for the pedal action; adjustable master cylinders; refined brake fluids; more robust brake lines; discs replacing drums, and more exotic and reformulated metallurgy for the friction components are amongst the evolutionary modifications made to the basic hydraulic design, but the operation remains essentially unchanged since the end of World War I.

But the beginning of the end of this 107-year-old concept can easily be envisioned thanks to major advances in electronics, materials and demands.

During the second decade of the 21^st Century the industry began unveiling “brake-by-wire” (BBW) systems, bringing electronics deeply into the mix. These initial BBW systems were wet ones – hydraulics still brought the activation to the wheel brakes, but now the impetus came when an electronic signal, not direct human-generated pedal pressure, activated the piston system within the master cylinder.

This type of “wet” BBW allowed the electronic input to come from the driver’s brake pedal as well as advanced driver-assistance system (ADAS) control units to activate the brakes. This meant vehicles could have systems like automatic-emergency braking (AEB) or advanced electronic stability control.

The rest of this article can be found in the April 2024 issue of BrakeLine magazine. Subscribe to our mailing list to download your free copy.