AAR M-114 Railway Bogie Coil  Inner & Outer Springs for Railway Bogie

Our AAR M-114 Railway Bogie Coil Springs are precision-engineered helical compression springs designed for the primary suspension systems of freight wagons, locomotives, and passenger coaches. Manufactured in strict compliance with AAR Specification M-114 (Helical Springs, Heat-Treated Steel), these springs provide critical load-bearing, shock absorption, and vibration damping functions that directly determine train running safety, stability, and ride comfort.

Available in two primary configurations:

• Outer Springs – Primary load-bearing springs with larger diameters, providing the main suspension capacity

• Inner Springs – Smaller-diameter springs nested within outer springs, supplementing stiffness and preventing resonance

Key design features:

• Nested spring design with opposite windings (adjacent inner and outer springs have opposing helix directions) to neutralize torque during compression and prevent coil interference

• Closed, squared and ground ends for uniform load distribution and stable seating

• Hot-coiled or cold-coiled manufacturing processes, followed by quenching and tempering heat treatment

• Surface shot peening for enhanced fatigue resistance

• Color coding or part number stamping for positive identification and lifecycle tracking

All springs are manufactured from high-grade spring steel (typically AISI 5160H alloy steel), and undergo rigorous quality control including static and dynamic load testing, magnetic particle inspection, hardness testing, and dimensional verification (free height, solid height, outside diameter, bar diameter, squareness, parallelism, and bearing surface flatness). Our manufacturing facility is certified under AAR M-1003 and ISO 9001

Technical Specifications Table

Manufacturing & Inspection Standards Table

Standard	Description	Application
AAR M-114	Helical Springs, Heat-Treated Steel – Primary design & manufacturing specification	All load-bearing and snubber springs
AAR M-112	Steel Bars, Carbon, for Railway Springs – Raw material specification	Spring wire/bar stock
AAR S-332 ~ S-338	Spring dimensional and performance standards	Free height, solid height, OD, bar diameter, squareness, parallelism, bearing surface flatness
AAR S-339 ~ S-343	Spring nesting/grouping standards	Inner/outer spring matching and grouping
AISI 5160H	Alloy spring steel – chemical composition & hardenability	Material selection
ASTM A-125	Standard for steel springs	Manufacturing & testing
AAR M-1003	Quality Assurance Specification	Manufacturing facility certification

 

Typical Applications

• Freight Cars – Heavy-haul, unit trains, bulk commodity, intermodal

• Locomotives – Diesel-electric and electric locomotives

• Passenger Coaches – High-speed and conventional passenger trains

• Metro & Light Rail Vehicles – Urban transit systems