Hydraulic Excavator Folding Middle Arm for Lower Transport Height

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing hydraulic excavators face limitations in transportation height due to the need to disassemble the front device into components to comply with regulations, and the restricted working range of the working tool is narrowed by the length of the middle arm, which cannot be extended without exceeding height restrictions during transport.

Innovation Solution

The hydraulic excavator is designed with a bisected middle arm comprising a first and second middle arm connected by a pivot pin and an extractable connection pin, allowing the arms to fold into a compact configuration for transport while maintaining a long working range by integrating the arms during operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the middle arm is made longer to widen the working range, then the working efficiency is improved, but the transportation height exceeds the legal limit

Engineering Contradiction:
Improveworking efficiencyVSAvoidtransportation height
Core Design Contradiction:
ProductivityVSLength of moving object

Solution Approach 1:

The middle arm is divided into a first middle arm and a second middle arm that can be separated. During transportation, the second middle arm is detached and stored separately, allowing the first middle arm to be folded at a reduced height. During operation, both segments are reconnected to form the full-length middle arm, providing the necessary working range while complying with transportation height restrictions.

Inventive Principle:
Principle #1Segmentation

2Length of moving object

If the middle arm is made shorter to reduce transportation height, then the transportation compliance is improved, but the working range becomes narrow

Engineering Contradiction:
Improvetransportation heightVSAvoidworking range
Core Design Contradiction:
Length of moving objectVSArea of stationary object

Solution Approach 1:

The middle arm configuration is made dynamic through the ability to connect and disconnect the first and second middle arms. The system transitions between a short configuration (first middle arm only) for transportation and a long configuration (first and second middle arms connected) for operation, allowing the structure to adapt its effective length based on operational requirements while maintaining compliance with transportation regulations.

Inventive Principle:
Principle #15Dynamics

3Length of moving object

If the front device is disassembled into components for transportation, then the transportation height restriction is met, but the preparation time and labor increase

Engineering Contradiction:
Improvetransportation heightVSAvoidpreparation time
Core Design Contradiction:
Length of moving objectVSLoss of time

Solution Approach 1:

The front device is segmented such that only the second middle arm needs to be detached for transportation, while the first middle arm remains connected to the upper structure. This minimal segmentation approach reduces the disassembly and reassembly operations required compared to complete disassembly, thereby reducing preparation time and labor while still achieving compliance with transportation height restrictions.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3859100B1Work machine
Publication Date: 2025.11.05 HITACHI CONSTRUCTION MACHINERY CO LTD
  • EP3859100B1 patent drawingFigure 1
  • EP3859100B1 patent drawingFigure 2
  • EP3859100B1 patent drawingFigure 3(a)~3(b)

AI summary

There is provided a work machine in which the transportation height of a front device having a boom, a middle arm, and an arm can be reduced, and the working range of the front device can be widened to improve working efficiency. The middle arm 12, which is a constituent member of the front device 4, is bisected into a first middle arm 17 and a second middle arm 18, wherein the first middle arm 17 is rotatably connected to the tip side of an upper boom 11 and has one end part of a middle arm cylinder 22 attached thereto, and the second middle arm 18 is rotatably connected to the rear end side of an arm 13 and has one end part of an arm cylinder 24 attached thereto. The first middle arm 17 and the second middle arm 18 are connected to each other at two locations by an inner pivot pin 20 that is prevented from falling out and an extractable outer connection pin 21. When the connection pin 21 is extracted from the first middle arm 17 and the second middle arm 18, the second middle arm 18 rotates around the pivot pin 20 to be folded with respect to the first middle arm 17.