Crawler Undercarriage Tensioning via Adjustable Stop Mechanism

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Solution Overview

Problem

Existing chain drive systems for crawler cranes and excavators face issues with maintaining optimal chain tension, as wear and tear lead to reduced tension and sagging, causing irregular wear and potential derailment, while over-tightening reduces durability. Current tensioning methods, such as hydraulic cylinders, require complex pressure regulation and expensive components.

Innovation Solution

A chain drive system with an adjustable stop mechanism limits the displacement of the sprocket or idler wheel, allowing for variable chain tension adjustment without changing hydraulic pressure, preventing over-tightening and optimizing durability by maintaining constant pressure with a hydraulic cylinder unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the chain tension is increased to counteract wear and sagging, then the chain guidance is improved, but the durability of the chain is reduced due to over-tightening

Engineering Contradiction:
Improvechain guidanceVSAvoidchain service life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The tensioning device allows dynamic adjustment of chain tension based on operational conditions. The chain tension can be increased during working operations to ensure proper guidance and decreased during driving operations to extend chain life, transforming a static tensioning system into a dynamic one that adapts to different operational phases

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the tension parameter of the chain according to operational mode. By adjusting the tensioning force to different levels (high tension during work, low tension during transport), the system optimizes both chain guidance and durability by matching tension parameters to specific operational requirements

Inventive Principle:
Principle #35Parameter changes

2Force

If hydraulic pressure is increased to tension the chain, then the chain tension is improved, but the device complexity increases due to need for pressure relief valves and regulation components

Engineering Contradiction:
Improvechain tensionVSAvoidhydraulic regulation components
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The invention extracts and removes the complex pressure regulation components (pressure relief valves, regulators) from the hydraulic system. By using a simplified hydraulic circuit without these components, the system achieves chain tensioning through direct hydraulic pressure application, reducing device complexity while maintaining effective tensioning capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The hydraulic system is designed to self-regulate chain tension without external control components. The hydraulic pressure naturally tensions the chain to the required level, and the system maintains this tension automatically without needing additional regulation mechanisms, making the hydraulic circuit self-sufficient

Inventive Principle:
Principle #25Self-service

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 adjustable stop mechanism ensures optimal chain tension is maintained, reducing wear and extending the service life of the crawler chain by preventing over-tightening and eliminating the need for expensive pressure relief valves, thus enhancing the durability and operational efficiency of the chain drive.

Implementation Method 1

The pressure applied in the hydraulic cylinder determines the tension applied to the chain

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

A hydraulic cylinder or a helical spring, for example, is used as a tensioning device

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP2409902B8Track drive and work machine
Publication Date: 2015.10.14 LIEBHERR WERK NENZING

AI summary

The present invention relates to a tracked undercarriage for a working machine, in particular for a crawler crane or a crawler excavator, comprising a drive track (20), at least one slidably mounted sprocket (30), in particular an idler or guide wheel, and at least one tensioning device for tensioning the track, wherein at least one stop is provided that limits the displacement of the slidably mounted sprocket. The invention further relates to a working machine, in particular a crawler crane or a crawler excavator, with such a tracked undercarriage.