Work Machine Travel Mode Steering Control via Pilot Depressurization

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Solution Overview

Problem

Work machines equipped with primary and secondary steering controls face challenges in ensuring safe operation on public roads, as the secondary steering control can inadvertently interfere with primary steering, particularly when transitioning from work mode to travel mode, requiring a reliable method to deactivate the secondary steering control to prevent unpredictable machine movements.

Innovation Solution

A work machine with a speed range control and drive system that allows selection of low and high ground speed ranges, featuring a travel mode control that disables the tool actuation system and secondary steering control, ensuring only the primary steering control is operable during travel mode, achieved through a common pilot pressure supply that is depressurized when travel mode is selected, and an optional secondary steering deselector control for explicit disabling of secondary steering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the secondary steering control is enabled for off-road work operations, then the ease of operation is improved, but the reliability deteriorates due to potential interference with primary steering control on public roads

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies the dynamics principle by making the secondary steering control dynamically switchable between enabled and disabled states based on machine operating conditions. The control system automatically disables the secondary steering control when the machine is traveling on public roads, while enabling it during off-road work operations. This dynamic adaptation allows the system to optimize ease of operation during work while ensuring reliability during road travel, resolving the contradiction between these two requirements.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the secondary steering control is deactivated during road travel, then the reliability is improved, but the ease of operation worsens due to loss of steering control capability

Engineering Contradiction:
ImprovereliabilityVSAvoidease of operation
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system dynamically adjusts the availability of secondary steering control based on the machine's operational context. During road travel, the secondary steering control is deactivated to ensure reliability, while during off-road work operations, it is reactivated to restore ease of operation. This conditional switching resolves the contradiction by ensuring that the appropriate control capability is available when needed without compromising safety during road travel.

Inventive Principle:
Principle #15Dynamics

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 solution ensures safe and predictable machine operation on public roads by disabling the secondary steering control and tool actuation during travel mode, allowing only the primary steering control to be used, thereby preventing inadvertent movements and enhancing operator safety and convenience.

Implementation Method 1

achieved through a common pilot pressure supply that is depressurized when travel mode is selected

Methodology Applied
Scientific EffectDepressurisation: Depressurisation

Data Source

PatentEP3575501B1Work machine with travel mode and secondary steering controls
Publication Date: 2023.08.23 CATERPILLAR INC

AI summary

A work machine 1 with a tool actuation system and primary and secondary steering controls 60, 61 is operable in both first and second gear in both work mode and travel mode. A user operable travel mode control 50, 50' is arranged to disable both the tool actuation system and the secondary steering control 61 when travel mode is selected, optionally by depressurising a common pilot supply 17 of pressurised fluid to pilot valves 11, 64 of the tool actuation and steering systems. Secondary steering may be disabled by a deselector control 51, 51' which must be operated before travel mode can be selected.