Editorial Technical Reference

Bolster

This page explains how Bolster is classified within Other Transport Equipment 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 a rail chassis that connects the truck frame to the car body through the center plate and side bearings.

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Product Specifications

Technical details and manufacturing context for Bolster

Definition
The bolster is a critical structural member in railway vehicle chassis systems, typically located at the center of each truck (bogie). It serves as the primary interface between the truck frame and the car body, transmitting vertical loads, lateral forces, and longitudinal forces. The bolster contains the center plate opening that receives the car body's center pin, allowing for rotation during curves while maintaining vertical support. It also provides mounting points for side bearings that control rocking and roll motions. The bolster functions as a load-bearing beam that distributes the car body weight evenly to the truck's side frames through spring groups. During operation, it allows controlled rotational movement between the car body and truck through the center plate connection while resisting excessive lateral and longitudinal displacements through friction and bearing surfaces. The bolster's design enables the truck to pivot relative to the car body during curves while maintaining stability on straight track. Typical parameters include a center plate diameter of 300–500 mm, side bearing span of 1500–2000 mm, static load capacity of 200–400 kN, dynamic load capacity of 150–300 kN, yield strength of 345–450 MPa, hardness of 150–220 HBW, weight of 300–600 kg, overall length of 2000–2600 mm, width of 300–400 mm, height of 200–300 mm, center plate surface flatness of 0.2–0.5 mm, side bearing surface roughness of 1.6–3.2 μm, operating temperature range of -40 to 70 °C, and corrosion protection class C3–C4 per ISO 12944. Materials commonly used include cast steel, forged steel, and high-strength alloy steel. Standards referenced include GB/T 5600, GB/T 1591, GB/T 231.1, GB/T 1184, and GB/T 1031. These values are directory references and must be verified for the specific model and application with the legal manufacturer or supplier.
Working Principle
The bolster functions as a load-bearing beam that distributes the car body weight evenly to the truck's side frames through spring groups. During operation, it allows controlled rotational movement between the car body and truck through the center plate connection while resisting excessive lateral and longitudinal displacements through friction and bearing surfaces. The bolster's design enables the truck to pivot relative to the car body during curves while maintaining stability on straight track.
Common Materials
Cast steel, Forged steel, High-strength alloy steel
Technical Parameters
ParameterTypical rangeNotes & selection driver
Center Plate Diameter300–500 mmMatches car body center plateGB/T 5600
Side Bearing Span1500–2000 mmDetermines roll stability
Static Load Capacity200–400 kNPer bolsterGB/T 5600
Dynamic Load Capacity150–300 kNFatigue rated
Yield Strength345–450 MPaMaterial grade dependentGB/T 1591
Hardness150–220 HBWEnsures wear resistanceGB/T 231.1
Weight300–600 kgPer bolster
Overall Length2000–2600 mmFits truck frame
Overall Width300–400 mmFits truck frame
Overall Height200–300 mmFits truck frame
Center Plate Surface Flatness0.2–0.5 mmEnsures even load distributionGB/T 1184
Side Bearing Surface Roughness1.6–3.2 μmReduces frictionGB/T 1031
Operating Temperature-40–70 °CMaterial impact toughness
Corrosion ProtectionC3–C4Coating systemISO 12944

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
  • Center plate Part
    Provides the rotating connection point for the car body center pin
    Material: Hardened steel
  • Side bearing pads Part
    Control rocking motion and provide friction damping between car body and truck
    Material: Rubber composite or friction material
  • Spring seat Part
    Supports and positions the suspension spring group
    Material: Steel
  • Wear plates Part
    Provide wear surfaces for friction elements and reduce maintenance requirements
    Material: Hardened steel or alloy
  • Bolster Body
    The beam itself — it spans the truck and carries the car body load into the spring groups.

Application & selection

Application Fit & Sizing Matrix

Operational Limits
pressure: Static load up to 250 kN, dynamic load up to 150 kN
other spec: Maximum deflection: 5 mm under full load, corrosion resistance: ISO 12944 C4
temperature: -40°C to +85°C
Media Compatibility
✓ Rail freight car bodies ✓ Heavy-haul locomotive frames ✓ Passenger railcar underframes
Unsuitable: High-speed rail applications (>200 km/h) due to vibration and fatigue considerations
Sizing Data Required
  • Maximum vertical load (kN)
  • Car body weight and center of gravity
  • Required lateral stiffness (kN/mm)

Risk, maintenance & compliance

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause
Material fatigue and cracking
Cause: Cyclic loading from pressure fluctuations, vibration, or thermal expansion/contraction leading to stress concentration at weld points or structural joints
Corrosion and material degradation
Cause: Exposure to corrosive process fluids, atmospheric conditions, or galvanic corrosion due to improper material selection or coating failure
Maintenance Indicators
  • Visible cracks, deformation, or bulging in the bolster structure
  • Unusual vibration, rattling noises, or audible stress sounds during operation
Engineering Tips
  • Implement regular non-destructive testing (NDT) inspections using ultrasonic or magnetic particle methods to detect early-stage fatigue cracks
  • Apply protective coatings compatible with process environment and establish cathodic protection systems where applicable to prevent 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 A36/A36M-19 (Standard Specification for Carbon Structural Steel) CE Marking (EU Machinery Directive 2006/42/EC)

Quoted from the published standard.

Manufacturing Precision
  • Bore Diameter: +/-0.05mm
  • Surface Flatness: 0.15mm per 300mm
Quality Inspection
  • Dimensional Verification with CMM
  • Magnetic Particle Inspection
Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
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Inspection readiness
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Manufacturers of Bolster

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Frequently Asked Questions

What is the primary function of a bolster in a rail chassis?

The bolster is a structural component that connects the truck frame to the car body. It transmits vertical, lateral, and longitudinal forces, and allows controlled rotation during curves via the center plate and side bearings.

What materials are commonly used for bolsters?

Common materials include cast steel, forged steel, and high-strength alloy steel. The specific material grade affects properties like yield strength and hardness, which must be confirmed for the actual application.

Which standards are referenced for bolster parameters?

Standards such as GB/T 5600, GB/T 1591, GB/T 231.1, GB/T 1184, and GB/T 1031 are referenced for various parameters. These are procurement references and do not guarantee compliance; verification with the manufacturer is required.

How should I verify the suitability of a bolster for my application?

You must check model-specific values such as load capacities, dimensions, and material properties against your requirements. Always consult the legal manufacturer or supplier to confirm that the bolster meets your operational and regulatory needs.

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:

Rail chassis
View system integration details

Industrial Ecosystem & Supply Chain Structure

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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