Semi-Trailer Fifth Wheel Weighing for Accurate Support Load

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Solution Overview

Problem

Existing semi-trailer weight measurement systems inaccurately distinguish between vertical and horizontal forces due to the rigid connection of the kingpin to the fifth wheel, leading to distorted vertical load determinations.

Innovation Solution

A weighing system that mechanically decouples the kingpin from the fifth wheel plate, allowing only vertical forces to be measured by a fixedly connected kingpin and independent fifth wheel plate, using a measuring system to accurately determine support load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the kingpin is rigidly connected to the fifth wheel plate, then the structural stability is improved, but the measurement precision of vertical load deteriorates due to inclusion of horizontal forces

Engineering Contradiction:
Improvestructural stabilityVSAvoidvertical load measurement precision
Core Design Contradiction:
Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The system separates the kingpin connection from the fifth wheel plate by introducing a movable connection mechanism with degrees of freedom. The kingpin is rigidly connected to the semi-trailer frame, while the fifth wheel plate can move independently relative to the kingpin, allowing mechanical decoupling of force components for accurate measurement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A movable connection mechanism acts as an intermediary between the kingpin and the fifth wheel plate. This intermediary component enables the transmission of vertical forces to the measuring system while allowing horizontal forces to be absorbed by the movable connection, thus protecting the measurement from distortion.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If a rigid connection is used between kingpin and fifth wheel, then the device complexity is reduced, but the measurement precision deteriorates due to force distortion

Engineering Contradiction:
Improveconnection structure complexityVSAvoidsupport load measurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The connection between the kingpin and the fifth wheel plate is made dynamic rather than static. The fifth wheel plate is allowed to move independently with respect to the kingpin, creating a dynamic system that can adapt to different force directions. This dynamic connection enables the system to differentiate between vertical and horizontal forces, improving measurement precision without excessive complexity.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If horizontal forces are included in the measurement, then the ease of operation is improved by simpler measurement setup, but the measurement precision of vertical load deteriorates

Engineering Contradiction:
Improvemeasurement setup simplicityVSAvoidvertical load determination accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The system extracts horizontal forces from the measurement path by allowing the fifth wheel plate to move independently relative to the kingpin. The movable connection absorbs horizontal force components, extracting them from the force transmission path to the measuring system. This leaves only vertical forces to be measured, ensuring high precision without complicating the overall setup.

Inventive Principle:
Principle #2Taking out (Extraction)

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 system provides highly accurate support load measurements by isolating horizontal forces from the measurement, enhancing the precision of load determination and enabling real-time monitoring for applications like precision farming.

Implementation Method 1

a measuring system (13) arranged between the fastening means (11) and the fifth wheel plate (12), wherein the measuring system (13) is configured to measure a force acting on the fifth wheel plate (12)

Methodology Applied
Scientific EffectForce measurement:

Data Source

PatentEP4425117B1Weighing system for direct detection of the support load of semi-trailers and semi-trailers with such a weighing system
Publication Date: 2026.03.25 ANNABURGER NUTZFAHRZEUG
  • EP4425117B1 patent drawingFigure 1
  • EP4425117B1 patent drawingFigure 2~3
  • EP4425117B1 patent drawingFigure 4~5

AI summary

The present invention relates to a weighing system (1) for directly measuring the support load of a semi-trailer (2), comprising at least: a fastening means (11) for attaching a kingpin (111) to a frame (22) of the semi-trailer (2); a fifth wheel plate (12) for interacting with a fifth wheel coupling (31) of a tractor unit (3); and a measuring system (13) arranged between the fastening means (11) and the fifth wheel plate (12), wherein the measuring system (13) is configured to measure a force acting on the fifth wheel plate (12). It is characterized in that the kingpin (111) is rigidly connected to the frame (22) by means of the fastening means (11); and that the fifth wheel plate (12) is configured to move independently relative to the kingpin (111).In the weighing system (1) according to the invention, almost all horizontal forces generated by the vehicle dynamics are directed into the frame (22) via the decoupled kingpin (111) without passing through the measuring system (13), and mainly vertical forces are taken into account in the support load measurement via the semi-trailer plate (12), which advantageously increases its accuracy.