Trailer Hitch Cam Radius Gradient Wear Tolerance

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Solution Overview

Problem

Existing trailer hitch mechanisms for agricultural tractors are prone to failure due to wear-induced shape changes in the cam and spherical cap, leading to coupling issues or jamming, especially under rough operating conditions.

Innovation Solution

A trailer hitch design where the ball head, cam, and carrier form a solid unit, with a cam having a larger radius of curvature in the upper area than the lower area, and a pivot axis closer to the ball head, ensuring a continuous transition and reduced sensitivity to shape deviations, allowing for automatic coupling and reliable operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cam and spherical cap are subject to wear during operation, then the shape of these components changes, but this leads to coupling problems or jamming

Engineering Contradiction:
Improvecoupling reliabilityVSAvoidshape stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by varying the radius of curvature along the cam surface. The cam has a larger radius of curvature in the upper area and a smaller radius in the lower area, creating different geometric parameters in different zones. This allows the mechanism to tolerate wear-induced shape changes better, as the gradient design provides a range of acceptable contact points rather than a single critical point.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cam is designed with non-uniform local properties - specifically, different radii of curvature in different areas. The upper area has a larger radius while the lower area has a smaller radius, creating localized geometric characteristics that optimize different aspects of the coupling operation and provide tolerance to wear in specific zones.

Inventive Principle:
Principle #3Local quality

2Device complexity

If the adjustment mechanism is simplified with fewer components, then the mechanism becomes more reliable, but the sensitivity to cam shape changes increases

Engineering Contradiction:
Improvemechanism complexityVSAvoidmechanism reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent resolves this contradiction by implementing parameter changes in the cam geometry - specifically a gradient in the radius of curvature from the lower area to the upper area. This geometric parameter variation compensates for the simplified mechanism design, providing tolerance to wear and shape changes without requiring complex adjustment mechanisms with multiple components.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the radius of curvature of the cam is made larger in the upper area, then the mechanism tolerates shape changes better, but the cam geometry becomes more complex

Engineering Contradiction:
Improvewear toleranceVSAvoidcam geometry
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The cam is designed with non-uniform local properties - specifically, different radii of curvature in different areas. The upper area has a larger radius while the lower area has a smaller radius, creating localized geometric characteristics that optimize different aspects of the coupling operation and provide tolerance to wear in specific zones.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies curvature principles by designing the cam surface with varying radii of curvature. The transition from a smaller radius in the lower area to a larger radius in the upper area creates a smooth curved profile that guides the spherical cap through the coupling motion while tolerating wear-induced shape changes.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 design results in a trailer hitch with improved reliability and reduced susceptibility to wear, enabling smooth automatic coupling and uncoupling, even under harsh agricultural conditions, with a simpler adjustment mechanism and fewer components.

Implementation Method 1

The cam is actuated by a drawbar when it is inserted into the coupling mouth, so that the carrier and thus also the ball head are adjusted

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

The spherical cap is pressed into the coupling mouth, it presses against the cam and pivots the carrier

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2639086B1Trailer coupling for a vehicle
Publication Date: 2016.09.07 SAUERMANN FRANZ
  • EP2639086B1 patent drawingFigure 1
  • EP2639086B1 patent drawingFigure 2
  • EP2639086B1 patent drawingFigure 3

AI summary

The trailer coupling (1) has a support (4) with a ball head (6) adjusted between a coupling position and a release position. The support is pivoted about a pivot axis (5) and is fixedly connected to a cam (9) operated by an universal ball joint. The radius of curvature of the cam the upper region is larger than the radius of curvature in the lower region.