Editorial Technical Reference

Reaction Plate/Housing

This page explains how Reaction Plate/Housing 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 structural component in brake/clutch assemblies that provides mounting and reaction force transmission.

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Product Specifications

Technical details and manufacturing context for Reaction Plate/Housing

Definition
The reaction plate/housing is a critical component within brake and clutch assemblies that serves as the mounting structure and force transmission element. It provides the rigid foundation against which the friction materials (brake pads or clutch plates) apply pressure, converting rotational energy into thermal energy through friction. In brake systems, it's typically part of the caliper assembly; in clutch systems, it's integrated with the pressure plate assembly. The component is manufactured from cast iron, aluminum alloy, or steel, with material selection depending on the application's load and thermal requirements. For aluminum alloy versions, a common grade is A380 (ASTM B85), which offers a balance of strength and castability. The reaction plate/housing must meet specific dimensional and surface requirements to ensure proper sealing and function. Key parameters include a burst pressure of at least 2.5 MPa, and a proof pressure of 2.0 MPa. The operating temperature range is -40 to 85°C, limited by seal materials. Surface flatness must be ≤0.05 mm (ISO 1101), and surface roughness should be Ra 0.8–1.6 μm (ISO 1302). Hardness is specified as 50–60 HB (ISO 6506) to ensure wear resistance. The weight typically ranges from 0.5 to 1.2 kg, and the overall diameter is 150–250 mm, fitting standard brake assemblies. These values are reference ranges for directory purposes; actual specifications must be confirmed with the legal manufacturer or supplier for the specific model and application. The reaction plate/housing is a safety-critical part, and its integrity is essential for reliable braking and clutch operation. Regular inspection for wear, deformation, or cracking is recommended, and any signs of damage should prompt replacement. When selecting or replacing this component, verify that the material, dimensions, and performance characteristics match the original equipment specifications.
Working Principle
The reaction plate/housing provides a stationary or semi-stationary surface against which friction materials are pressed. When hydraulic or mechanical force is applied, the friction material contacts the reaction surface, creating friction that slows or stops rotational motion (in brakes) or transfers torque (in clutches). The housing portion encloses and protects internal components while providing structural integrity. The reaction plate must withstand the applied forces without permanent deformation, as specified by the proof pressure. The surface finish and flatness are critical for even pressure distribution and sealing, preventing fluid leaks in hydraulic systems. Over time, wear or thermal cycling can affect the surface, leading to reduced performance or failure. Therefore, the component must be inspected periodically and replaced if it no longer meets the required tolerances.
Common Materials
cast iron, aluminum alloy, steel
Technical Parameters
ParameterTypical rangeNotes & selection driver
Burst Pressure≥2.5 MPaSafety factor of 1.5 over max operating
Operating Temperature-40–85 °CSeal material limits
Surface Flatness≤0.05 mmCritical for sealingISO 1101
Surface RoughnessRa 0.8–1.6 μmSealing surface finishISO 1302
Material GradeA380Die-cast aluminum alloyASTM B85
Hardness50–60 HBEnsures wear resistanceISO 6506
Proof Pressure2.0 MPaNo permanent deformation
Weight0.5–1.2 kgDepends on size
Overall Diameter150–250 mmFits standard brake assemblies

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
  • Housing Body
    The housing itself: encloses and locates the internal parts and provides the mounting interface.
  • Mounting Flange Part
    Provides attachment points to the vehicle or machinery structure
    Material: steel
  • Friction Surface Part
    Area where brake pads or clutch plates make contact to create friction
    Material: cast iron
  • Cooling Fins/Ribs Part
    Dissipates heat generated during friction operations
    Material: aluminum alloy

Application & selection

Application Fit & Sizing Matrix

Operational Limits
pressure: Up to 20 MPa (200 bar) static, 15 MPa (150 bar) dynamic
other spec: Max torque transmission: 500 Nm, Surface finish: Ra 0.8 μm, Flatness tolerance: 0.05 mm
temperature: -40°C to +200°C continuous, +250°C peak
Media Compatibility
✓ Hydraulic brake fluid (DOT 3/4/5.1) ✓ Mineral-based clutch fluid ✓ Dry particulate-free air systems
Unsuitable: Chlorinated solvents or strong acidic environments
Sizing Data Required
  • Maximum torque requirement (Nm)
  • Mounting bolt pattern dimensions (PCD and bolt size)
  • Required stiffness/deflection limit under load

Risk, maintenance & compliance

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause
Fatigue cracking
Cause: Cyclic stress from pressure fluctuations or vibration leading to crack initiation and propagation, often at stress concentrators like bolt holes or welds.
Corrosion pitting
Cause: Chemical attack from process fluids or atmospheric exposure, exacerbated by stagnant conditions or galvanic couples, leading to localized material loss and potential perforation.
Maintenance Indicators
  • Visible cracks or distortion on the plate/housing surface, especially near connections or high-stress areas.
  • Unusual vibration or noise during operation, indicating loosening, imbalance, or internal damage.
Engineering Tips
  • Implement regular non-destructive testing (e.g., ultrasonic or dye penetrant inspection) to detect early-stage cracks or thinning before catastrophic failure.
  • Apply protective coatings or cathodic protection and ensure proper drainage to minimize corrosion, and use compatible materials to avoid galvanic corrosion.

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
ASTM A370 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products CE Marking - Conformity with EU Directives for Pressure Equipment (PED 2014/68/EU)

Quoted from the published standard.

Manufacturing Precision
  • Bore Diameter: +/-0.025 mm
  • Flatness: 0.05 mm per 100 mm
Quality Inspection
  • Dye Penetrant Test (PT) for Surface Defects
  • Coordinate Measuring Machine (CMM) for Dimensional Verification
Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
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Inspection readiness
Confirm test methods, calibrated equipment, sampling plans, and traceable reports.
Supplier transparency
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Manufacturers of Reaction Plate/Housing

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Frequently Asked Questions

What materials are used for the reaction plate/housing?

The reaction plate/housing can be made from cast iron, aluminum alloy, or steel. For aluminum alloy, a common grade is A380 per ASTM B85. The material choice depends on the application's load and thermal requirements.

What are the key performance parameters for this component?

Key parameters include burst pressure ≥2.5 MPa, proof pressure 2.0 MPa, operating temperature -40 to 85°C, surface flatness ≤0.05 mm (ISO 1101), surface roughness Ra 0.8–1.6 μm (ISO 1302), and hardness 50–60 HB (ISO 6506). These are reference ranges; verify with the manufacturer.

How does the reaction plate/housing function in a brake system?

In a brake system, the reaction plate provides a stationary surface against which brake pads are pressed. When hydraulic force is applied, the pads contact the reaction surface, creating friction that converts rotational energy into heat, slowing or stopping the vehicle.

What maintenance or inspection is required?

Regular inspection for wear, deformation, or cracking is recommended. Check surface flatness and roughness if performance issues arise. Replace the component if it no longer meets specifications or shows signs of damage.

Data basis: editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Related equipment

Applied To / Applications

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

Brake/Clutch Assembly
View system integration details

Industrial Ecosystem & Supply Chain Structure

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Reaction Plate/Housing.

reaction plate

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.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 12 October 2026

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