Editorial Technical Reference

Brake Master Cylinder

This page explains how Brake Master Cylinder is classified within Motor Vehicle Manufacturing. Technical values and manufacturer relationships are research references; confirm the current specification and supplier evidence for each order.

Technical Definition & Core Assembly

A brake master cylinder is a critical component in hydraulic braking systems. It converts mechanical force from the brake pedal into hydraulic pressure, which is then distributed to the wheel cylinders or calipers to apply braking force.

Product Specifications

Technical details and manufacturing context for Brake Master Cylinder

Definition
A brake master cylinder is a critical component in hydraulic braking systems. It converts mechanical force from the brake pedal into hydraulic pressure, which is then distributed to the wheel cylinders or calipers to apply braking force. This part is typically made from aluminum alloy, cast iron, or steel, with surface treatments such as anodizing to enhance wear and corrosion resistance. The master cylinder operates on the principle of a piston compressing brake fluid in a primary chamber when the pedal is depressed, creating pressure that travels through brake lines to actuate the wheel brakes. It often features a dual-circuit design for safety, with separate chambers for front and rear brakes. Key parameters include bore diameter (20.64–31.75 mm), stroke (25–50 mm), operating pressure (1.0–1.6 MPa), burst pressure (≥20 MPa), operating temperature (-40–85 °C), leakage rate (≤0.5 cm³/min), reservoir capacity (0.2–0.5 L), and weight (0.8–1.5 kg). These values are reference ranges that must be confirmed for the specific vehicle model and application. Standards such as ISO 4926 are referenced for verification, but they do not imply certification or compliance of any particular product. When selecting a brake master cylinder, consider the vehicle's braking system requirements, pedal force, fluid volume, and compatibility with existing brake lines and seals. Verification questions should include checking the bore diameter and stroke against the vehicle's specifications, ensuring the operating pressure range matches the system, and confirming the burst pressure provides an adequate safety margin. Maintenance signals include excessive pedal travel, low brake fluid level, or visible leaks, which may indicate seal degradation or internal wear. Failure boundaries are defined by the burst pressure and leakage rate; exceeding these limits can lead to brake failure. Always verify model-specific values and standards with the legal manufacturer or supplier before installation.
Working Principle
When the brake pedal is depressed, a pushrod moves the master cylinder piston forward, compressing brake fluid in the primary chamber. This creates hydraulic pressure that travels through brake lines to actuate the wheel brakes. The master cylinder typically has a dual-circuit design for safety, with separate chambers for front and rear brakes.
Common Materials
Aluminum alloy, Cast iron, Steel
Technical Parameters
ParameterTypical rangeNotes & selection driver
Bore Diameter20.64–31.75 mmDetermines fluid volume and pedal forceISO 4926
Stroke25–50 mmAffects fluid displacement and pedal travel
Burst Pressure≥20 MPaSafety margin over max operating pressureISO 4926
Operating Temperature-40–85 °CSeal materials degrade outside this rangeISO 4926
Leakage Rate≤0.5 cm³/minExcessive leakage causes pedal fadeISO 4926
Reservoir Capacity0.2–0.5 LMust cover brake pad wear and fluid expansion
Weight0.8–1.5 kgAffects vehicle unsprung mass
MaterialADC12Aluminum alloy for corrosion resistanceJIS H5302
Surface TreatmentAnodizedEnhances wear and corrosion resistanceMIL-A-8625

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM
  • Cylinder Body
    The cylinder itself: the bore the piston runs in and the pressure boundary around it.
  • Piston Assembly
    Creates hydraulic pressure by compressing brake fluid
    Material: Aluminum alloy or steel
  • Reservoir
    Stores and supplies brake fluid to the master cylinder
    Material: Plastic or aluminum
  • Pushrod Part
    Transfers force from brake pedal to master cylinder piston
    Material: Steel
  • Seals and Cups Part
    Prevents fluid leakage and maintains pressure
    Material: Rubber or synthetic compounds
  • Springs Part
    Returns piston to resting position when brake pedal is released
    Material: Spring steel

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Industrial Ecosystem & Supply Chain Structure

Complementary Systems
Downstream Applications
Specialized Tooling

Application Fit & Sizing Matrix

Operational Limits
pressure: Up to 200 bar (2900 psi)
other spec: Fluid viscosity range: 1-15 cSt at 40°C
temperature: -40°C to 120°C
Media Compatibility
✓ DOT 3/4/5.1 brake fluid ✓ Mineral oil-based hydraulic fluids ✓ Glycol-based hydraulic fluids
Unsuitable: Corrosive or abrasive slurries
Sizing Data Required
  • Vehicle brake system pressure requirement (bar/psi)
  • Master cylinder bore diameter (mm/in)
  • Required fluid displacement volume per stroke (ml)

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause
Internal Seal Degradation
Cause: Chemical breakdown of rubber seals due to moisture absorption, brake fluid contamination, or incompatible fluid types, leading to loss of hydraulic pressure and brake fluid leaks.
Bore Corrosion and Pitting
Cause: Moisture ingress into brake fluid causing electrochemical corrosion of the aluminum or cast iron cylinder bore, resulting in seal damage, fluid bypass, and reduced braking efficiency.
Maintenance Indicators
  • Soft or spongy brake pedal that sinks gradually when pressure is applied
  • Visible brake fluid leaks around the master cylinder reservoir or mounting area
Engineering Tips
  • Use only manufacturer-recommended brake fluid types and change fluid every 2 years to prevent moisture accumulation and chemical degradation
  • Install a desiccant-type brake fluid reservoir cap and ensure all system connections are sealed to minimize air and moisture ingress

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards
ISO 4925: Road vehicles - Brake master cylinders ANSI/SAE J1153: Brake Master Cylinder Performance Requirements DIN 74361: Brake master cylinders for motor vehicles

Quoted from the published standard.

Manufacturing Precision
  • Bore diameter: +/-0.01mm
  • Surface finish (cylinder wall): Ra 0.4μm max
Quality Inspection
  • Pressure cycling endurance test
  • Leakage test (hydraulic and vacuum)

Manufacturers of Brake Master Cylinder

4 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.

Anhui Leading Forklift Parts Co., Ltd.
Shenyang, Liaoning, CN
Listed on the company's own website · profile compiled by CNFX from public sources
Listed there as: “Brake Master Cylinder”
View source page ↗ leadingforkliftparts.com · checked 2026-09-16
BOC Autoparts
Ningbo, Zhejiang, CN
Listed on the company's own website · profile compiled by CNFX from public sources
Listed there as: “Brake Master Cylinder”
View source page ↗ bocautoparts.com · checked 2026-09-14
Qingdao Promising International Co., Ltd.
Qingdao, Shandong, CN
Listed on the company's own website · profile compiled by CNFX from public sources
Listed there as: “Servo Brake Master Cylinder Assy”
View source page ↗ promisingcn.cn · checked 2026-09-16
Zhejiang Jishang Automobile Components CO., LTD.
Wenzhou, Zhejiang, CN
Listed on the company's own website · profile compiled by CNFX from public sources
Listed there as: “Brake Master Cylinder”
View source page ↗ chinanaiba.com · checked 2026-08-28

Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

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Frequently Asked Questions

What is the function of a brake master cylinder?

It converts mechanical force from the brake pedal into hydraulic pressure, which is distributed to the wheel brakes to apply braking force.

What materials are commonly used for brake master cylinders?

Aluminum alloy, cast iron, and steel are typical materials, with surface treatments like anodizing for corrosion resistance.

What are the key parameters to verify when selecting a brake master cylinder?

Bore diameter, stroke, operating pressure, burst pressure, operating temperature, leakage rate, reservoir capacity, and weight. These must be confirmed for the specific application.

What maintenance signals indicate a problem with the master cylinder?

Excessive pedal travel, low brake fluid level, or visible leaks may indicate seal degradation or internal wear, requiring inspection or replacement.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.
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