Side frame: Load Capacity 15-25 tons per side, Width 150-250 mm

Component Specifications

Definition

The side frame is a longitudinal structural member of a bogie frame assembly in railway rolling stock, designed to connect the axle boxes, support the vehicle body through the bolster, and distribute vertical, lateral, and longitudinal forces. It typically features a box-section or I-beam design with precisely machined interfaces for suspension components, brake rigging, and other bogie elements.

Working Principle

The side frame functions as a rigid beam that transfers loads from the vehicle body through the bolster to the axle boxes and wheelsets. It maintains proper wheel alignment, absorbs dynamic forces during operation, and provides mounting points for secondary suspension systems and braking components.

Materials

High-strength low-alloy steel (HSLA) grades such as ASTM A572 Grade 50 or EN 10025 S355J2, with yield strength ≥355 MPa, impact toughness requirements at -20°C, and controlled carbon equivalent for weldability.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Width	150-250 mm
Height	300-450 mm
Length	1800-2500 mm
Weight	150-300 kg
Weld Quality	Full penetration welds, UT tested
Load Capacity	15-25 tons per side
Surface Finish	SA 2.5 blasted, primer coated

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

Standards

ISO 1005, DIN 4322, AAR M-202

Parent Products

This component is used in the following industrial products

Bogie frame

The primary structural component of a bogie that supports the vehicle body and connects to the wheelsets.

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Engineering Analysis

Risks & Mitigation

Fatigue cracking at stress concentration points
Corrosion in harsh environments
Weld failure under dynamic loading
Dimensional wear affecting wheel alignment

FMEA Triads

Trigger: Stress concentration at sharp corners or weld transitions
Failure: Fatigue crack propagation leading to structural failure
Mitigation: Implement radiused transitions, shot peening for compressive stresses, regular NDT inspections

Trigger: Inadequate corrosion protection
Failure: Section loss reducing load capacity
Mitigation: Apply multi-layer coating systems, specify corrosion-resistant steel grades, implement regular maintenance inspections

Trigger: Improper heat treatment during manufacturing
Failure: Brittle fracture or reduced fatigue life
Mitigation: Strict process control, mechanical property verification, Charpy impact testing

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±1.0 mm on critical bore diameters, ±2.0 mm on overall dimensions, flatness within 1.5 mm/m

Test Method

Static load testing to 1.5x design load, fatigue testing per ISO 12107, hardness testing, chemical analysis, dimensional verification

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Side frame

Manufacturer profiles associated with Side frame.

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Related Components

Center Sill

The center sill is the primary longitudinal structural beam in a rail chassis that supports vertical loads and distributes forces throughout the railcar frame.

Prestressing Tendons

High-strength steel tendons used to apply compressive stress in concrete bridge beams for enhanced load capacity and durability.

Primary suspension

Primary suspension system connecting bogie frame to axle boxes in railway vehicles for vibration damping and load transfer.

Coupler Head

Coupler head is the front connecting component of railway couplers that engages with mating couplers to join rail vehicles.

Frequently Asked Questions

What is the primary function of a side frame in a bogie?

The side frame primarily provides structural integrity to the bogie assembly, distributing loads between the vehicle body and wheelsets while maintaining proper wheel alignment and supporting suspension components.

How are side frames inspected for defects?

Side frames undergo non-destructive testing including magnetic particle inspection for surface cracks, ultrasonic testing for internal flaws, dimensional verification of critical interfaces, and visual inspection for corrosion or damage.

Can side frames be repaired or must they be replaced when damaged?

Minor repairs following approved welding procedures are possible for certain defects, but significant cracks, deformation, or wear beyond specified limits typically require replacement to maintain structural integrity and safety.

Data Basis

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

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.

Side frame