Log Handler Reach Limitation Based on Payload Stability

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Solution Overview

Problem

Existing log handlers lack effective means to ensure safe and convenient operation, particularly in rough terrain, by accurately determining payload and stability to prevent tipping.

Innovation Solution

A log handler equipped with systems to determine payload and stability parameters using geometric data, limiting reach and preventing tipping by comparing actual moment to tipping limits, and dynamically adjusting the horizontal extension based on payload and geometry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the horizontal reach of the work equipment is increased to improve operational convenience, then the log handler becomes more prone to tipping over, compromising stability

Engineering Contradiction:
Improvehorizontal reachVSAvoidtipping resistance
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent implements dynamic reach limitation that adapts to the actual payload. The system continuously monitors payload weight and automatically adjusts the maximum permissible horizontal reach accordingly. When payload decreases, the system allows greater horizontal extension, and when payload increases, it restricts reach to maintain stability. This dynamic adaptation resolves the contradiction by making the reach limit flexible rather than fixed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs a feedback mechanism where the actual payload is measured and used to adjust the reach limitation. The system compares the current payload with pre-stored characteristic data to determine the safe horizontal reach limit. This closed-loop feedback ensures that the log handler operates within stable parameters while maximizing the usable horizontal reach for the given load condition.

Inventive Principle:
Principle #23Feedback

2Stability of the object's composition

If a fixed maximum horizontal reach limitation is applied to ensure stability, then the operational flexibility is reduced when carrying lighter payloads

Engineering Contradiction:
Improvetipping preventionVSAvoidoperational flexibility
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The system transitions from a static reach limitation to a dynamic one based on payload conditions. The control unit continuously evaluates the actual payload and adjusts the maximum horizontal reach limit in real-time. This allows the log handler to achieve maximum operational flexibility with light payloads while maintaining strict stability limits with heavy payloads, thus resolving the contradiction between stability and adaptability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of reach limitation from a constant value to a variable that depends on payload weight. The system stores characteristic data representing different payload-reach combinations and selects the appropriate limit based on the current load. This parameter change enables the system to adapt to varying operational conditions while ensuring stability is never compromised.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If payload determination systems are added to enable dynamic reach control, then operational safety is improved, but device complexity increases

Engineering Contradiction:
Improveoperational safetyVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent leverages the existing payload determination system of the wheel loader for a dual purpose: traditional load management and stability control. By reusing the already-installed weighing sensors and control unit for reach limitation purposes, the system achieves improved operational safety without adding separate payload measurement hardware. This multi-functional use resolves the contradiction by avoiding redundant systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing control unit of the wheel loader performs the additional function of determining reach limitation based on payload. The system uses its own internal sensors and processing capabilities to self-regulate the horizontal reach, eliminating the need for external or separate monitoring systems. This self-service approach improves safety while minimizing added complexity.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4332306B1Log handler
Publication Date: 2026.01.28 LIEBHERR WERK BISCHOFSHOFEN GMBH
  • EP4332306B1 patent drawingFigure 1
  • EP4332306B1 patent drawingFigure 2
  • EP4332306B1 patent drawingFigure 3

AI summary

The present invention relates to a log handler with a wheel loader base unit, on which a work attachment is located that is movable relative to the base unit and comprises a tool, in particular a log grapple device, wherein the log handler has first means configured to determine the payload, and wherein the log handler has second means configured to determine a parameter representative of the stability of the log handler based on the payload determined by the first means and on geometric data of the log handler.