Shear Pin Shock Protector for Rail Vehicle Coupling Shaft

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Solution Overview

Problem

The existing connection between the linkage and the bearing block in rail-mounted vehicles is inefficient in disengaging upon exceeding a critical impact force due to uneven load distribution and multiple stress types on shear pins, which complicates simultaneous activation and increases the risk of fatigue failure.

Innovation Solution

Designing the pivot pin as a shock protector with a concentric recess and a shearing element having a predetermined breaking region, allowing the connection to disengage effectively upon critical impact, with a feather key system for torque transmission and a floating bearing to minimize transverse forces, thus simplifying the stress on the shearing element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If multiple shear pins are used to connect the linkage to the bearing block, then the connection strength is improved, but the complexity of simultaneous activation increases and reliability decreases due to uneven load distribution

Engineering Contradiction:

Improveconnection strengthVSAvoidsimultaneous activation reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The connection is segmented into multiple shear pins arranged symmetrically around the pivot axis, allowing each pin to bear equal load and activate simultaneously when the critical impact force is exceeded

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shear pins are positioned asymmetrically relative to the loading direction but symmetrically relative to the pivot axis, ensuring uniform load distribution among all pins during normal operation and simultaneous failure during overload conditions

Inventive Principle:

Principle #4Asymmetry

2Device complexity

If shear pins serve both as connecting elements and shock protectors, then the device complexity is reduced, but the precision of overload protection response deteriorates due to dispersed actuation force

Engineering Contradiction:

Improvedevice complexityVSAvoidoverload protection response precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The shear pins perform dual functions: connecting the linkage to the bearing block during normal operation and acting as shock protectors by shearing off when critical impact forces are exceeded, eliminating the need for separate connecting elements and shock protection mechanisms

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The shear pins are designed with specific material properties and geometric parameters (cross-sectional area, length, material strength) that allow them to maintain connection strength under normal loads while enabling precise shear failure at a predetermined critical impact force threshold

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If pin pretensioning is increased to improve connection stability, then the connection reliability is improved, but the risk of fatigue failure and bolts working loose increases

Engineering Contradiction:

Improveconnection stabilityVSAvoidfatigue failure resistance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The shear pins are pre-installed with controlled pretensioning that ensures stable connection during normal operation while preventing excessive stress concentration that would lead to fatigue failure, balancing initial stability with long-term reliability

Inventive Principle:

Principle #10Preliminary action

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

This solution enables precise and effective overload protection by optimizing the shearing element's predimensioning and reducing stress types, enhancing the reliability and longevity of the connection by ensuring only one type of stress is applied to the shearing element.

Implementation Method 1

a shearing element (4, 4') having a predetermined breaking or separating region (9, 9')

Methodology Applied

Scientific EffectShear stress: Shear Stress

Implementation Method 2

at least one region of the peripheral edge of the bearing disc (3, 3') to form a sliding surface for a pivot bearing formed in the bearing block (20)

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

An elastomer spring mechanism is integrated into the linkage itself which serves in absorbing the tractive and impact forces occurring in normal driving conditions

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10507850B2Device for connecting a coupling shaft to a car body of a track-guided vehicle

Publication Date: 2019.12.17 VOITH PATENT GMBH

AI summary

A device for connecting a coupling shaft to a car body of a track-guided vehicle, wherein the device includes a linkage connected to the coupling shaft and a bearing block connectable to the car body to which the linkage is articulated by means of at least one pivot pin so as to be pivotable in a horizontal plane. At least one pivot pin is designed as a shock protector and thereto comprises a bearing disc having a concentrically arranged recess and a shearing element having a breaking or separating region. A bearing block-side region of the shearing element is accommodated in the recess of the bearing disc and a linkage-side region of the shearing element is accommodated in a pin seat of the linkage.