What is the difference between clutch booster and brake booster?
Jul 17, 2025
What is the difference between clutch booster and brake booster?
1. Function positioning difference
The clutch booster is designed for manual transmission. Its core functions are:
Amplify the pedal force by 5–8 times (the boost ratio of ordinary cars is about 1:6.5)
Help to completely separate the friction plate (stroke control accuracy ±0.5mm)
Achieve fast return (reset time ≤0.3 seconds)
For example, the clutch booster Isuzu systems are engineered specifically to meet the operational demands of heavy-duty vehicles, offering consistent performance in high-load environments.
The brake booster serves the braking system:
The typical boost ratio is more than 1:10 (SUV models can reach 1:12)
It is necessary to establish continuous hydraulic pressure (working pressure is usually 2–4 MPa)
Equipped with emergency brake assist function (pressure rises suddenly when EBA system intervenes)
2. Comparison of structural principles
Structural features of clutch booster:
Using diaphragm air chamber (diameter 80–120mm)
Hydraulic piston diameter is usually 18–25mm
Integrated accumulator (pre-stored pressure 0.4–0.6MPa)
Typical structure includes:
Control valve body
Hydraulic cylinder
Air pressure chamber
Push rod mechanism
China has become a major source for these products. A clutch booster factory in China typically specializes in large-scale production with strict quality control, making it a competitive supplier in the global aftermarket.
Brake booster core components:
Vacuum chamber (diameter 200–300mm)
Dual diaphragm design (standard for modern models)
Electronic vacuum pump (essential for new energy vehicles)
Key subsystems:
Vacuum check valve
Input push rod group
Reaction plate mechanism
Hydraulic master cylinder interface
Leading brake booster manufacturers focus on performance, safety certification, and electronic integration to meet the rising demand in both traditional and EV platforms.
3. Differences in working characteristics
Parameters
|
Clutch Booster
|
Brake Booster
|
Working pressure
|
0.8–1.2MPa
|
2–4MPa
|
Response time
|
50–80ms
|
30–50ms
|
Stroke
|
120–150mm
|
40–60mm
|
Temperature range
|
-30℃~120℃
|
-40℃~150℃
|
4. Comparison of fault modes
Common faults of clutch booster:
Hydraulic oil pressure leakage (aging of sealing ring)
Assist failure (insufficient accumulator pressure)
Slow pedal return (return spring fatigue)
Typical faults of brake booster:
Vacuum leakage (damaged diaphragm)
Uneven assist (worn reaction plate)
Hard pedal (blocked check valve)
5. Maintenance points
Clutch booster maintenance:
Check hydraulic oil every 30,000 kilometers
Exhaust air regularly (recommended every 2 years)
Pay attention to pedal free travel (standard 10–15mm)
Brake booster maintenance:
Annual inspection of vacuum line
Keep engine compartment clean
Pay attention to brake fluid replacement cycle (2 years/40,000 kilometers)
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