Overload Clutch Positioning in Agricultural Drive Trains

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Solution Overview

Problem

Conventional overload clutches in agricultural implements often trigger falsely due to torsional vibrations from the cardan shaft, leading to uncontrolled responses and inadequate protection of the central input gear from overloads, especially in high-performance harvesters with increased processing capacities.

Innovation Solution

The overload protection is positioned after the central input gear but before the main work rotor in the drive train, reducing the influence of torsional vibrations and ensuring reliable protection against overloads, with the overload clutch arranged in the main drive train to secure the full drive power and protect subsequent auxiliary drive trains.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the overload clutch is positioned before the central input gear in the drive train, then the central input gear is protected from overloads, but the overload clutch triggers falsely due to torsional vibrations from the cardan shaft

Engineering Contradiction:

Improveprotection of central input gearVSAvoidtriggering accuracy of overload clutch

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary element - the central input gear itself - positioned between the cardan shaft and the overload clutch. This intermediary absorbs and dampens the torsional vibrations from the cardan shaft before they reach the overload clutch, preventing false triggering while maintaining the protective function. The central input gear acts as a vibration isolator, allowing the overload clutch to respond only to genuine overload conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the overload clutch from its conventional position directly connected to the cardan shaft and relocates it to a position downstream of the central input gear. This separation removes the harmful influence of cardan shaft vibrations from the overload clutch's operation while preserving the protective function for the central input gear and downstream components.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If the overload clutch is positioned after the central input gear, then false triggering from torsional vibrations is reduced, but the protection effect on the central input gear is weakened

Engineering Contradiction:

Improvetriggering accuracy of overload clutchVSAvoidprotection of central input gear

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments the drive train into distinct functional zones: the central input gear handles vibration absorption from the cardan shaft, while the overload clutch positioned downstream handles overload protection. This segmentation allows each component to perform its specialized function optimally - the central input gear filters vibrations, and the overload clutch provides precise overload detection without interference.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If additional bearing points are provided between the cardan shaft and overload clutch to absorb transverse vibrations, then transverse vibrations are reduced, but the cardan shaft length is shortened leading to increased buckling at the joints

Engineering Contradiction:

Improvetransverse vibrationsVSAvoidbuckling resistance of cardan shaft

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent converts the previously harmful torsional vibrations from the cardan shaft into a beneficial damping effect by positioning the central input gear downstream of the cardan shaft. The central input gear's inherent mechanical characteristics naturally absorb and dampen these vibrations, transforming what was a harmful oscillation source into a vibration-damping mechanism that protects the overload clutch without requiring additional bearing points that would compromise cardan shaft structural integrity.

Inventive Principle:

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

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 arrangement effectively prevents false triggering and ensures the central input gear and subsequent drive components are protected from overloads, maintaining precise control and reducing the risk of damage from torsional vibrations, while also simplifying the handling and maintenance of the cardan shaft.

Implementation Method 1

the drive train has a central input gear which can be connected to the power take-off shaft of the tractor via a cardan shaft

Methodology Applied

Scientific EffectCardan shaft mechanism: Gimbal

Implementation Method 2

This overload clutch slips, shears off or disengages in another way in the event of excessive drive power or torque surges

Methodology Applied

Scientific EffectFriction slip: Friction

Data Source

PatentEP4056004B1Agricultural device

Publication Date: 2024.07.24 ALOIS POETTINGER MASCHFAB

Figure 1
Figure 2

AI summary

The present invention relates to an agricultural implement for mounting on a tractor, comprising a drive train for driving working units of the implement including a working rotor, wherein the drive train has a central input gearbox which can be connected to the tractor's power take-off shaft via a cardan shaft, and an overload clutch, wherein the overload clutch is provided downstream of the central input gearbox and protects at least the said working rotor.