Multi-Axle Steering System Tie Rod Overload Protection

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Solution Overview

Problem

Steering systems in vehicles with multiple axles face overload issues during heavy operating conditions, making steering difficult or impossible and risking component damage, especially in industrial or commercial vehicles.

Innovation Solution

A steering system equipped with hydraulic cylinders that act on the levers of the steering system to increase steering force and reduce overload on tie rods by directly engaging with the steering idler arms, ensuring consistent steering performance even in demanding conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a hydraulic steering gear is used to increase steering force, then the steering capability is improved, but the tie rod connecting the steering axles becomes overloaded and may be damaged

Engineering Contradiction:
Improvesteering forceVSAvoidtie rod strength
Core Design Contradiction:
ForceVSStrength

Solution Approach 1:

A second hydraulic cylinder is introduced as an intermediary device between the steering axles. This cylinder acts as a mediator that directly compensates for force imbalances in the tie rod, preventing overload while maintaining steering capability. The second cylinder absorbs excess forces that would otherwise be transmitted through the tie rod connection.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If the vehicle is equipped with more than one steering axle to improve load capacity, then the vehicle can handle heavier loads, but the linkages connecting the steering axles become overloaded during steering operations

Engineering Contradiction:
Improveload capacityVSAvoidlinkage force
Core Design Contradiction:
PowerVSForce

Solution Approach 1:

The second hydraulic cylinder serves as a force-balancing intermediary that directly acts on one of the steering axles. It compensates for the additional forces generated by having multiple steering axles, preventing these forces from being transmitted as excessive loads through the linkage system connecting the axles.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Length of moving object

If the tie rod is made longer to connect distant steering axles, then the multi-axle configuration is enabled, but the tie rod becomes more susceptible to deformation, breaking, or bending under high force

Engineering Contradiction:
Improvetie rod lengthVSAvoidtie rod resistance to deformation
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

The second hydraulic cylinder acts as a force-distributing intermediary that reduces the peak loads transmitted through the long tie rod. By directly compensating for force imbalances at the axle level, it prevents the tie rod from experiencing excessive tensile and thrust stresses that would lead to deformation or failure, even though the tie rod must span a longer distance between axles.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution allows for reliable steering in heavy conditions by distributing the steering force more evenly, reducing the risk of tie rod deformation or damage, and enabling smooth operation in full load or stationary scenarios.

Implementation Method 1

an hydraulic cylinder (14) is present and one of its ends is fixed to one end of the external part of the side member (1), while the other end is fixed to the second arm of the steering idler arm (8)

Methodology Applied
Scientific EffectHydraulic force: Hydraulic Press

Data Source

PatentEP2261101B1Steering system for automotive vehicles comprising at least two steering axles
Publication Date: 2012.03.07 ASTRA VEICOLI IND
  • EP2261101B1 patent drawingFigure 1

AI summary

The subject of the present invention is a steering system for a vehicle having more steering axles (6,10) equipped with one or more hydraulic cylinders (14,15) which act on the leverages (8,11) of the steering system in order to increase the steering force and to avoid overloading a tie rod (9) which connects the leverages of the steering axles.