Construction Quick Coupler Hook Geometry for Bucket Retention

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Solution Overview

Problem

Existing quick couplers for construction equipment are dangerous due to the risk of the bucket falling during attachment, posing a significant safety hazard, especially when operators mistakenly rotate the coupler in the wrong direction.

Innovation Solution

A coupler device with a design featuring a front hook that extends upwards beyond the trunnion and incorporates a recess, ensuring the trunnion remains engaged even if the operator rotates in the wrong direction, and a locking mechanism that prevents disengagement, enhancing safety by preventing the bucket from falling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the hook head portion extends upwards beyond the center of the trunnion, then the reliability of the coupling is improved, but the device complexity increases

Engineering Contradiction:
Improvecoupling reliabilityVSAvoidhook structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The hook head portion is designed with an asymmetric geometry that extends upwards beyond the center of the trunnion. This asymmetric configuration ensures that the hook cannot disengage from the trunnion even during unintended 180-degree rotation, as the extended head portion would collide with the connection device flanks before complete rotation occurs. This resolves the technical contradiction by improving coupling reliability through geometric constraint while maintaining relatively simple hook structure.

Inventive Principle:
Principle #4Asymmetry

2Object-affected harmful factors

If the recess is incorporated into the base body to prevent over-rotation, then the safety is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvesafety hazard from bucket fallVSAvoidbase body manufacturing
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The recess is pre-formed in the base body at a strategic position that limits the rotation angle of the coupler relative to the connection device. This preliminary geometric constraint prevents over-rotation and potential bucket detachment before it can occur during operation. The recess acts as a mechanical stop that engages with the connection device flanks, providing passive safety without requiring active control systems or complex assembly procedures.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the hook head extends higher than prior art designs, then the prevention of accidental detachment is improved, but the ease of operation during coupling may be reduced

Engineering Contradiction:
Improveprevention of accidental detachmentVSAvoidcoupling operation ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The vertical dimension of the hook head portion is increased beyond conventional designs, extending it above the trunnion centerline. This parameter change creates a geometric interlock that prevents accidental detachment during coupling operations. The extended head portion provides a larger engagement envelope, ensuring that even if the operator initiates rotation in the wrong direction, the hook geometry prevents complete disengagement while still allowing proper coupling when oriented correctly.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4644612A1High security quick coupler
Publication Date: 2025.11.05 KLAC IND SA
  • EP4644612A1 patent drawingFigure 1~2
  • EP4644612A1 patent drawingFigure 3~4
  • EP4644612A1 patent drawingFigure 5~6

AI summary

A coupler device comprising a coupler (1), or quick coupler, intended to be attached to an arm of a construction machine, and a connection device (2), intended to be attached to a tool such as a bucket; the connection device comprising at least one trunnion (5; 6; 5, 6), preferably two trunnions (5, 6) respectively front and rear;the coupler comprising a base body from which, on a front side, at least one hook is issued, the hook or each hook (7) comprising a stem-forming region and a hook-head-forming region (72), which extends upwards from the stem-forming region to form, with the base body, at least one receiving cavity (200) for the trunnion or one of the trunnions having an opening on the top which extends between the base body and the respective head-forming region of the respective hook: characterized in that when the trunnion or one of the trunnions is inside the receiving cavity in contact with the stem-forming region, the head-forming region protrudes upwards from the center of the circular section of the trunnion;