Wheel Loader Boom Float Control for Low-Shock Ground Contact

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Solution Overview

Problem

Existing automatic lowering control systems in work vehicles cause a large shock when an attachment is lowered under its own weight onto the ground, and the transition to a floating state requires complex manual operations.

Innovation Solution

A work vehicle equipped with a controller that detects the attachment's position and switches the boom operation valve to a floating state when the attachment reaches a predetermined position, allowing the attachment to be grounded easily and minimizing shock.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If automatic lowering control is used to lower the attachment to a predetermined position, then the attachment can be lowered accurately, but a large shock occurs when the attachment contacts the ground

Engineering Contradiction:
Improvelowering position accuracyVSAvoidshock at ground contact
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The control device switches the boom operation valve to a floating state before the attachment reaches the ground, allowing the attachment to be lowered under its own weight without hydraulic resistance. This preliminary switching action prevents the sudden shock that would occur if the valve remained in the lowering state until ground contact

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically switches the boom operation valve between different states (lowering state and floating state) based on the attachment's position. The valve transitions from a fixed lowering state to a floating state when the attachment reaches a predetermined position, enabling smooth deceleration and ground contact without shock

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If the attachment is lowered under its own weight after automatic lowering control, then shock is reduced, but the operation to manually bring the attachment to the floating state becomes complicated

Engineering Contradiction:
Improveshock at ground contactVSAvoidoperation complexity
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The control device automatically determines when to switch the boom operation valve to the floating state based on detection means (such as boom angle sensors or stroke sensors). This self-service automation eliminates the need for the operator to manually judge and operate the valve switching, simplifying the operation while maintaining shock reduction

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses detection means to monitor the boom position or stroke and provides feedback to the control device. Based on this feedback, the control device automatically switches the valve to the floating state at the appropriate moment, eliminating the need for complex manual operations and ensuring consistent shock-free grounding

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3584374B1Work vehicle
Publication Date: 2026.02.25 KOMATSU LTD
  • EP3584374B1 patent drawingFigure 1
  • EP3584374B1 patent drawingFigure 2
  • EP3584374B1 patent drawingFigure 3

AI summary

A controller (25) in a wheel loader (1) sets a boom cylinder (9) to a floating state when it is detected that a bucket (4) has reached a position where the bucket (4) is in contact with the ground during the execution of an automatic lowering control for automatically rotating and lowering a boom (3).