Derailment Risk Due to Coupler Jack-Knifing under Longitudinal Buff Force

Abstract

Numerous rail accidents occurred in recent years in Canada due to coupler jack-knifing under longitudinal in-train buff force. Interaction between coupler jack-knifing and transformed lateral force under a buff force shows an unstable and positive feedback. Mathematical analysis and case studies demonstrate the mechanical and track conditions, and operational misconducts as well, that led to such jack-knifing and derailments. Defences against this risky lateral jack-knifing are evaluated. Association of American Railroads Manual of Standards and Recommended Practices (AAR MSRP) Chapter II requirements on coupler angles, transformed lateral force, and safety check condition of cars on a 175 m radius (10°) curve with 890 kN (200 kips) in-train pull force are discussed.

Keywords

derailment transformed lateral force/vertical force coupler jack-knifing drawbar angle

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