EMB Line-Controlled Braking Trends & Market Outlook

Author: Johnny Liu, CEO at Dowway Vehicle

Published: June 15, 2026

Quick Summary of Key Facts

The Shift: Car makers are moving from hydraulic vacuum boosters to pure, “dry” Electro-Mechanical Braking (EMB).
EHB vs. EMB: Today’s Electro-Hydraulic Braking (EHB) uses hydraulic fluid. EMB is fluid-free, cutting response times to $\le 100\text{ms}$ while separating software control from physical hardware.
Commercial Heavy-Duty Vehicles: Trucks and buses are perfect for EMB. The system cuts over $70\%$ of air-braking parts, saves up to $100\text{kg}$ of chassis weight, and uses only $40\%$ of the energy required by pneumatic systems.
The Production Timeline: 2025 is the year for winter testing and pilot runs. Full mass production starts in late 2025 and 2026.
Market Scale: By 2030, China’s domestic EMB market is expected to pass $11.5\text{ billion RMB}$ ($15\%$ penetration rate).

1. Why Is the Traditional Vacuum Booster System Going Away?

For decades, the vacuum booster was the standard way to stop a gasoline-powered car. To understand why it is disappearing, we have to look at how it actually works.

+---------------------------------------------------------+
|                  Vacuum Booster System                  |
+---------------------------------------------------------+
|  [Input] Pedal ---> [Booster] Vacuum Booster --->       |
|  ---> [Execution] Master Cylinder ---> Wheel Calipers   |
+---------------------------------------------------------+

A traditional vacuum booster relies on three main parts:

The Input: The brake pedal.
The Booster: The physical vacuum booster chamber.
The Execution: The master cylinder and wheel calipers.

The booster pushrod connects directly to the brake pedal. A vacuum one-way valve connects to the engine’s intake manifold, using engine vacuum to build pressure. The master cylinder pushrod then pushes the piston inside the cylinder.

When you step on the pedal, air pressure differences in the booster create physical force. This force pushes brake fluid out of the reservoir, through the hydraulic lines, and into the calipers to squeeze the brake discs.

The Problem in the EV Era

Engine Dependency: Vacuum systems need a running combustion engine. If the engine stops, the braking assist disappears.
The Failed Fix: Early electric vehicles tried to use electric vacuum pumps (EVPs) to create vacuum pressure. But EVPs are loud, do not last long, and fail too often. The industry had to abandon them.
Too Heavy and Slow: These old setups are bulky and heavy. Because they rely on moving fluid through long tubes, they cannot stop a car fast enough to match modern safety software and automated driving sensors.

2. EHB vs. EMB: What Is the Difference?

To support active safety systems like automated emergency braking (AEBS), anti-lock brakes (ABS), and electronic stability control (ESC), we need brake-by-wire (BBW) systems. Today, this technology splits into two options: Electro-Hydraulic Braking (EHB) and Electro-Mechanical Braking (EMB).

       ┌── Two-Box (Separate iBooster + ESC; built-in redundancy)
  ┌─── EHB (Electro-Hydraulic)
  │    └── One-Box (Integrated; lighter, cheaper; requires high ESC expertise)
  │
BBW (Brake-by-Wire)
  │
  └─── EMB (Electro-Mechanical) ---> Pure "Dry" System (Direct Motor-on-Caliper)

2.1 EHB: The Interim Bridge

EHB systems keep traditional hydraulic calipers but use an electric motor to build fluid pressure. There are two EHB layouts:

Two-Box: This layout keeps the active booster (like Bosch’s iBooster) separate from the ESC. It uses two independent control units (ECUs), giving the car automatic backup safety. While reliable, it is bulky and expensive.
One-Box: This layout integrates the booster and ESC into a single unit with one ECU. It is smaller, lighter, and costs less. However, writing the software is highly complex.
- For High-Level Automation: To use a One-Box system in a Level 3 or Level 4 self-driving vehicle, manufacturers must add a Redundant Brake Unit (RBU) to act as an emergency backup.

2.2 EMB: The Pure “Dry” Target

EMB does away with hydraulic fluids, master cylinders, brake lines, and vacuum parts. Instead, high-torque electric motors sit directly on each wheel caliper to press the brake pads against the discs.

Feature	Old Vacuum System	EHB (Brake-by-Wire)	EMB (Pure Dry System)
Braking Medium	Air + Hydraulic Fluid	Hydraulic Fluid	None (Purely Electric)
Response Time	$>300\text{ms}$	$150\text{ms}$ to $200\text{ms}$	$\le 100\text{ms}$
Weight Change	Baseline ($100\%$)	$85\% – 90\%$ of baseline	Saves $80\text{kg} – 100\text{kg}$ on trucks
System Complexity	High	High	Low (wiring and motors only)
Software Link	None	Partial (Pressure-based)	Full (Direct electronic control)

The Main Benefits of EMB:

Incredible Speed: EMB applies full braking force in $\le 100\text{ms}$. This is faster than EHB ($150\text{ms}-200\text{ms}$) and legacy truck air brakes ($>400\text{ms}$).
True Digital Control: Because there is no physical fluid connection between the pedal and the wheel, engineers can write software to change how the brakes feel. You can update the braking behavior through over-the-air (OTA) updates.
Easier Maintenance: No brake fluid means no leaks, no need to flush the lines, and simpler assembly during vehicle manufacturing.

Let’s Look at EMB Costs:

In its initial release phase, the total bill of materials (BOM) cost for EMB is already close to a redundant EHB setup.
While EMB is slightly more expensive than a basic, non-redundant One-Box EHB, it costs about the same as a redundant One-Box + RBU setup (which is required by safety laws for high-level self-driving cars).
Once factories scale up, EMB costs will drop far below EHB.

3. What Technical Challenges Must EMB Solved First?

Squeezing a motor into a wheel assembly is incredibly difficult. The wheel area is one of the harshest places on a vehicle.

       ┌── Heat Damage (Up to 600°C friction heat)
       ├── Mechanical Abuse (High vibration, water, flying rocks)
EMB ───┼── Electrical Noise (Electromagnetic Interference - EMI)
Issues
       ├── Total Power Failures (Needs Dual-Power & Dual-Chip backups)
       └── Software Tuning (Syncing wheel motors with main vehicle controllers)

Extreme Heat ($600^\circ\text{C}$): Under heavy braking (like driving down a long steep mountain), brake discs reach temperatures up to $600^\circ\text{C}$. Because the EMB motor is bolted right onto the caliper, this heat transfers directly to the motor magnets. If they get too hot, the magnets can lose their magnetic charge, causing a loss of braking power.
Brutal Roads: The wheel unit must survive being submerged in water, hit by flying gravel, shaken by constant road vibrations, and exposed to electronic noise (EMI).
No Mechanical Backup: In a hydraulic car, if the power dies, your foot can still physically push fluid to stop the car. With EMB, a dead battery means no physical connection. To prevent this, EMB needs dual-power grids (like a 12V and 48V split) and two microprocessors running at the same time to handle sudden electrical failures.
Software Development: Writing code that allows wheel-end motors to talk to the main vehicle computer and driver-assist systems takes thousands of hours of track testing.

4. The Intermediate Step: Hybrid Braking (EHB + EMB)

To save on development costs and meet tough safety standards (like ISO 26262 ASIL-D), some automakers are combining both systems.

+-------------------------------------------------------------+
|               Hybrid Braking System (E.g., Brembo)          |
+-------------------------------------------------------------+
|  Front Wheels: EHB (Hydraulic pressure) -----------------+  |
|                                                          |  |
|  Rear Wheels: EMB (Pure Dry / Electric Caliper) ---------+  |
|                                                          |  |
|  Controlled by Dual ECUs (Back-up Redundancy) ------------+  |
+-------------------------------------------------------------+

Real-World Hybrid Examples:

Audi’s EHCB (Electric Hydraulic Combi Brake): This design uses a vacuum booster and an electric vacuum pump for the front wheels (EHB), but uses dry EMB on the rear wheels. This removes long, leaking brake lines running to the back of the car while keeping a traditional hydraulic loop up front.
Brembo’s SENSIFY: Brembo uses EHB on the front wheels and dry EMB on the back. It runs on two separate computers that control the front and back axles independently. If one axle fails, the other takes over to stop the vehicle.

5. Why Trucks and Buses are Adopting EMB Faster

While passenger cars have tiny margins and limited space, commercial vehicles (trucks, logistics vans, and heavy mining vehicles) are the perfect place to use EMB.

                   Pneumatic Air Brakes (Legacy Trucks)
                   - Response Latency: > 400ms
                   - Dozens of valves, tanks, and hoses
                   - Constantly drains engine power
                                  VS
                       EMB Dry Brakes (Modern Trucks)
                   - Response Latency: <= 100ms
                   - Saves 80kg to 100kg of chassis weight
                   - Uses only 40% of the energy

5.1 Replacing Complex Pneumatic Air Brakes

Heavy trucks traditionally use air brakes. These systems require heavy air compressors, drying units, large air tanks, and complicated networks of hoses and valves.

Dangerous Lag: Air systems take more than $400\text{ms}$ to react. On wet or snowy roads, that delay can cause a heavy truck to jackknife.
Wasted Fuel and Battery: The air compressor runs constantly, which burns extra fuel in diesel engines or drains valuable battery range in electric trucks.

5.2 The Benefits for Commercial Fleets

Weight Savings: EMB eliminates the heavy air tanks, compressors, and pneumatic hoses. This cuts the overall part count by over $70\%$ and drops the truck’s weight by $80\text{kg}$ to $100\text{kg}$. Less weight means fleets can carry more cargo.
Shorter Stopping Distance: With a reaction time of $\le 100\text{ms}$, EMB cuts a loaded truck’s stopping distance by over $10\%$.
High Efficiency: EMB uses just $40\%$ of the energy needed by traditional air brake systems, directly extending the range of battery-powered trucks.
Built-in Safety: EMB automatically integrates key safety software like ABS, ESC, and Traction Control (TCS) right into the wheel controllers.

5.3 Easy Packaging in Large Wheels

Heavy trucks have massive wheels (typically $22.5\text{ inches}$ or larger). This gives engineers plenty of room to install high-power electric motors and heavy cooling fins, easily solving the motor heat and magnet demagnetization problems that plague smaller passenger cars.

6. Market Size Projections (2025–2030): The Coming Growth

The rise of autonomous delivery vans, driverless haulers in mines, automated port shuttles, and Robotaxis is driving rapid demand for EMB.

EMB Market Growth Projection (China Domestic)
======================================================================
Year   Penetration   Average Unit Cost   Estimated Market Size
----------------------------------------------------------------------
2025   On-Vehicle Validation Phase
2026   1.0%          ~4,000 RMB          1.417 Billion RMB (Initial Phase)
2028   >5.0%         Prices Dropping     Scale Production Phase
2030   15.0%         Localized Supply    11.5+ Billion RMB (Mass Market)
======================================================================
CAGR (2026-2030): > 70%

The Adoption Timeline:

2025: The industry-wide testing phase. Suppliers are completing cold-weather winter testing and durability runs with major vehicle manufacturers.
2026 (The Start): Safety rules and regulations are expected to update.
- We project a $1\%$ penetration rate in China. At a system cost of $4,000\text{ RMB}$ per vehicle, the market will hit $1.417\text{ billion RMB}$.
2028 (Scaling Up): As local Chinese suppliers increase production, the cost of key parts (like precision ball screws and high-performance motors) will drop, pushing penetration past $5\%$.
2030 (Mass Production): EMB penetration is expected to reach $15\%$, driving the Chinese market past $11.5\text{ billion RMB}$. This represents a compound annual growth rate (CAGR) of over $70\%$ between 2026 and 2030.

7. Competitive Landscape: Who Is Building EMB?

The companies building EMB fall into three main groups.

             ┌── Global Tier-1 Giants (Bosch, Continental, ZF, Brembo)
             │   - Large patent portfolios; mature EHB customer bases
             │
EMB Market ──┼── Domestic Chassis Players (Bethel, APG, Fudi, Weststar)
Camps        │   - Close relationships with local automakers; rapid testing
             │
             └── Agile Tech Startups (Coordinate System, JiongYi, HSR, Qiangu)
                 - Affordable pricing; fast development of local components

7.1 Camp 1: Global Tier-1 Giants

The Players: Bosch, Continental, ZF, and Brembo.
The Strategy: These companies have dominated EHB for years. They have deep engineering budgets and started researching EMB decades ago.
Key Milestone: Bosch has secured production orders from three Chinese car manufacturers, with mass production planned for Q4 2025.

7.2 Camp 2: Established Domestic Chassis Suppliers

The Players: Bethel, Asia-Pacific Group (APG), Fudi Technology, and Weststar Group.
The Strategy: These suppliers use their existing factories and deep relationships with local car brands to launch trial fleets.
Key Milestone: Bethel completed winter testing for its four-wheel EMB prototype in August 2023. The company is building a manufacturing project to produce $600,000\text{ sets}$ of EMBs annually. It plans to start small-batch assembly in H2 2025 and full mass production in H1 2026.

7.3 Camp 3: Fast-Moving Tech Startups

The Players: Coordinate System, JiongYi Electronics, HSR, and Qiangu Technology.
The Strategy: Startups move incredibly fast. By sourcing local components and writing their own software, they offer pricing that legacy foreign brands cannot match.
Key Milestones:
- Coordinate System: This startup offers a full line-up of EMB motors ($25\text{kN}$, $35\text{kN}$, $45\text{kN}$, and $65\text{kN}$ clamping forces) and has set a flat cost of just $3,488\text{ RMB}$ per vehicle. They have secured joint development contracts, completed cold-weather vehicle testing, and will launch their EMB on the Dongfeng Forthing Xinghai V9 by late 2025.
- JiongYi Electronics: Completed winter testing using a $100\%$ fully localized domestic chip architecture. They have secured mass production contracts from leading vehicle manufacturers and plan to begin assembly in H2 2025 on a line designed to build $150,000\text{ sets}$ per year.
- HSR: Currently working on validation runs with several automakers, targeting Q3 2026 for mass production.
- Qiangu Technology: Released its A-sample hardware platform, aiming to start mass production in Q4 2026.

8. What This Means For Our Industry

The transition from hydraulic brakes to dry, electric brake-by-wire systems is already happening. While EHB remains the practical option for today’s standard passenger vehicles, EMB is fast approaching its commercial tipping point. Driven by heavy trucks, autonomous delivery fleets, and agile local startups, dry braking will soon become the standard.

For vehicle manufacturers, component suppliers, and investors, the 2025–2026 launch window is a critical moment. The companies that successfully deploy dry brake-by-wire systems now will lead the next generation of vehicle design.

FAQ: Common Questions About EMB Systems

Q: What is the main difference between EHB and EMB?

A: EHB still uses hydraulic fluid, while EMB is a completely dry, fluid-free system. EHB uses an electric motor to push hydraulic fluid through traditional lines to clamp the wheels. EMB replaces the fluid, master cylinder, and lines entirely with electric motors mounted directly on each brake caliper.

Q: When will EMB be mass-produced?

A: Mass production of EMB systems is scheduled to begin between late 2025 and mid-2026. Companies like Bosch, Bethel, and Coordinate System have scheduled production launches starting in Q4 2025, with several domestic Chinese models deploying the technology by 2026.

Q: Why are commercial vehicles adopting EMB faster than passenger cars?

A: Heavy trucks have more physical wheel space to cool the motors and benefit much more from the massive weight and fuel savings. EMB saves up to $100\text{kg}$ of chassis weight, cuts stopping distances by $10\%$, and fits easily inside large $22.5\text{-inch}$ commercial wheel rims that offer plenty of natural airflow.

Q: How much does an EMB system cost?

A: Currently, an EMB system costs around 3,500 to 4,000 RMB per vehicle. Startups like Coordinate System have introduced pricing structures as low as $3,488\text{ RMB}$ for a complete vehicle configuration, making it highly competitive with redundant hydraulic One-Box systems.

Dowway Vehicle