Legacy Hydraulic Brakes Being Replaced by EMB Systems as Automakers Accelerate Full-by-Wire Chassis Upgrades

Traditional automotive braking systems, which have relied on hydraulic mechanisms for over a century, consist of core components such as the brake pedal, vacuum booster, master cylinder, hydraulic lines, and calipers. These systems decelerate vehicles through mechanical-hydraulic linkage, offering simple architecture and high reliability—making them the industry standard for decades. In recent years, numerous automakers and suppliers have begun shifting toward Electromechanical Braking (EMB) technology. Chery’s Exeed EX7 has already entered mass production equipped with an EMB system; Huawei’s Zhijing claims to achieve a 100 km/h-to-stop braking distance within 30 meters; and Li Auto’s L9 Livis also adopts a fully brake-by-wire EMB architecture. The primary driver behind this shift is the heightened demand from autonomous driving for faster response times and greater braking precision. Conventional hydraulic systems require approximately 200 milliseconds from pedal depression to caliper activation—translating to over three additional meters of stopping distance at 120 km/h compared to brake-by-wire systems, significantly compromising emergency collision avoidance performance. Moreover, hydraulic systems struggle to enable precise, independent control of each wheel, limiting the safety redundancy required for advanced autonomous driving functions. Brake-by-wire technology has evolved through three generations: early Two-Box solutions separated the Electronic Stability Program (ESP) from electronic boost; subsequent One-Box designs integrated these modules to improve compactness and responsiveness, though still retaining hydraulic components; EMB, however, completely eliminates hydraulics—equipping each wheel with an independent motor that directly actuates the caliper via electrical signals. This reduces response time to under 100 milliseconds and enables individual wheel braking force modulation. EMB also offers advantages such as weight reduction and freed-up engine bay space, facilitating cabin layout optimization and overall vehicle lightweighting. However, its mass production faces significant challenges: in-wheel motors must withstand harsh conditions like high temperatures, mud, and water, necessitating multiple layers of redundancy to meet functional safety standards. Additionally, increased unsprung mass poses greater demands on chassis tuning and cost control. Currently, the Chery Exeed EX7 has become the world’s first vehicle to feature front-fitted, mass-produced EMB. The entire system was developed to meet ISO 26262 ASIL D—the highest automotive safety integrity level—with dual-redundant power and communication links. Notably, this system is supplied by Chinese startup Coordinate Intelligent, rather than traditional international Tier 1 suppliers. With China’s new national braking standard GB 21670-2025 now taking effect, the country has taken a global leadership position in brake-by-wire technology.