Shear Pin Coupling Lock Mechanism for Rail Vehicle Safety

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Solution Overview

Problem

Existing Scharfenberg-type center buffer couplings are prone to uncontrolled component failure and irreparable damage when tensile forces exceed design limits, leading to potential coupling arrangement instability and safety risks.

Innovation Solution

Designating the coupling eyebolt as a shear bolt with a predetermined breaking point allows for controlled separation of the coupling connection when excessive tensile forces are applied, ensuring safe release and easy repair by isolating the affected component.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the coupling locking means are designed to withstand high tensile forces, then the coupling strength is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvecoupling strengthVSAvoiddevice complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The coupling system is divided into two independent load paths: compressive forces are transmitted through the coupling head housings, while tensile forces are transmitted through the coupling locking means. This segmentation allows each component to be optimized for its specific function, reducing overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The coupling locking means are designed as replaceable components that can be easily replaced after reaching their service life or experiencing overload. This approach is more economical than designing the entire coupling system for extended service life, as the locking means can be independently replaced without replacing other components.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Strength

If the coupling locking means are designed to withstand high tensile forces, then the coupling strength is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvecoupling strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The coupling system is divided into two independent load paths: compressive forces are transmitted through the coupling head housings, while tensile forces are transmitted through the coupling locking means. This segmentation allows each component to be optimized for its specific function, reducing overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The coupling locking means are designed as replaceable components that can be easily replaced after reaching their service life or experiencing overload. This approach is more economical than designing the entire coupling system for extended service life, as the locking means can be independently replaced without replacing other components.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Device complexity

If conventional coupling locking means are used, then the coupling structure is simple, but uncontrolled component failure and irreparable damage occur under excessive tensile load

Engineering Contradiction:
Improvedevice complexityVSAvoidsafety under overload
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The coupling locking means are pre-designed with a predetermined breaking point that will fail at a specific tensile force threshold. This preliminary design ensures that when excessive load occurs, the failure happens in a controlled manner at the predetermined point, preventing uncontrolled damage to other components.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The potential harmful effect of excessive tensile force is converted into a beneficial safety feature. The predetermined breaking point causes the coupling locking means to fail in a controlled manner, transforming what would be a catastrophic uncontrolled failure into a manageable event that protects the rest of the coupling system.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Strength

If the coupling locking means are designed with high strength, then the coupling can withstand higher forces, but repairability decreases when failure occurs

Engineering Contradiction:
Improvecoupling strengthVSAvoidrepairability
Core Design Contradiction:
StrengthVSEase of repair

Solution Approach 1:

The coupling system is divided into two independent load paths: compressive forces are transmitted through the coupling head housings, while tensile forces are transmitted through the coupling locking means. This segmentation allows each component to be optimized for its specific function, reducing overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The coupling locking means are designed as replaceable components that can be easily replaced after reaching their service life or experiencing overload. This approach is more economical than designing the entire coupling system for extended service life, as the locking means can be independently replaced without replacing other components.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enables a controlled and safe separation of the coupling connection under overload conditions, preventing damage to adjacent components and allowing for straightforward repair by replacing only the modified coupling eyebolts, thus ensuring reliable operation and safety.

Implementation Method 1

the coupling eye bolt is designed as a shear bolt with a predetermined breaking point so that, in the event of an overload, a controlled component failure occurs at the breaking point

Methodology Applied
Scientific EffectShear stress: Shear Stress

Data Source

PatentEP4313719B1Automatic central buffer coupler for rail vehicles, and coupler assembly composed thereof
Publication Date: 2025.01.15 KNORR BREMSE SYST FUR SCHIENENFAHRZEUGE GMBH
  • EP4313719B1 patent drawingFigure 1~2
  • EP4313719B1 patent drawingFigure 3

AI summary

The invention relates to an automatic central buffer coupler for rail vehicles, comprising a Scharfenberg-type coupler head (1) having a coupler head housing (9) and having a coupling lock mechanism disposed in the coupler head housing, the coupling lock mechanism comprising: - a main pin (3); - a coupling hoop (5); - a coupling hoop pin (8); and - a disk (4); wherein, for the safety release of a coupling connection when a response force (FA) is exceed in the tension direction, the coupling hoop pin (8; 8') of the coupling lock mechanism is in the form of a shear pin. The invention can be applied to all designs of couplers having a parallelogram lock mechanism of the Scharfenberg type.