Large Square Baler Bale Spear Retraction With Active Latching

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Solution Overview

Problem

Baler implements face issues with the passive retraction system of the pawl becoming plugged with crop material, leading to incomplete withdrawal and reduced effectiveness in ejecting bales.

Innovation Solution

A bale ejection system with a frame rail, outer and inner carrier plates, and a linkage bar mechanism that includes a push and return stroke latch system to actively and positively insert and retract the bale spear, ensuring complete disengagement from the bale.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a passive retraction system using gravity and downward forces is used to retract the pawl, then the system is simple in structure, but the pawl becomes plugged with crop material and cannot fully retract

Engineering Contradiction:

Improvestructure simplicityVSAvoidpawl retraction completeness

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the passive mechanical retraction system (relying on gravity and downward forces) with an active mechanical retraction system using a linear actuator. The linear actuator provides controlled, reliable retraction force that is not dependent on gravitational forces or downward bale weights, ensuring complete pawl retraction even when the pawl becomes plugged with crop material.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a self-cleaning mechanism where the linear actuator actively retracts the pawl from the bale region, and the return stroke latch system automatically releases the pawl from any crop material engagement. This self-service approach eliminates the need for manual intervention or reliance on passive gravitational forces to clear the pawl.

Inventive Principle:

Principle #25Self-service

2Device complexity

If the pawl is not fully retracted, then the retraction mechanism remains simple, but the pawl rips out a groove of crop material during the return stroke

Engineering Contradiction:

Improveretraction mechanism complexityVSAvoidcrop material damage

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the passive gravity-based retraction with an active linear actuator system that provides controlled, sufficient retraction force. This ensures the pawl is completely pulled back from the bale region before the return stroke begins, preventing any contact with and damage to the crop material during the return stroke.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The linear actuator performs the retraction action before the return stroke begins, ensuring the pawl is fully withdrawn from the bale region in advance. This preliminary action prevents the pawl from contacting or damaging the crop material during the subsequent return stroke.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If an active linear actuator system is used to retract the pawl, then the pawl retraction is complete and reliable, but the device complexity increases

Engineering Contradiction:

Improvepawl retraction completenessVSAvoidretraction system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex passive retraction system (requiring precise gravitational and downward force balancing) with a simpler active system using a linear actuator. The linear actuator provides direct, controlled retraction force without relying on complex force interactions, actually reducing the overall system complexity while improving reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If the pawl region is left open for retraction, then the retraction mechanism is simple, but crop material fills and plugs the region

Engineering Contradiction:

Improveretraction mechanism complexityVSAvoidcrop material accumulation

Core Design Contradiction:

Device complexityVSQuantity of substance

Solution Approach 1:

The patent uses the linear actuator to actively pull the pawl out of the bale region, creating a positive retraction action that prevents crop material from filling and plugging the region. The active retraction mechanism continuously clears the area, preventing accumulation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The linear actuator provides continuous, repeated retraction actions during operation, continuously clearing the pawl region of crop material. This continuous useful action prevents the region from filling up, unlike passive systems that rely on intermittent gravitational forces.

Inventive Principle:

Principle #20Continuity of useful action

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 system ensures full and effective ejection of bales by maintaining the bale spear's active retraction and insertion, preventing damage to crop material during the return stroke.

Implementation Method 1

A linear actuator is attached to the inner carrier plate and operable to extend during a push stroke to move the inner carrier plate and the outer carrier plate in a first longitudinal direction parallel to and along the longitudinal axis. The linear actuator is operable to retract during a return stroke to move the inner carrier plate and the outer carrier plate in a second longitudinal direction opposite to the first longitudinal direction

Methodology Applied

Scientific EffectLinear actuator mechanical motion:

Implementation Method 2

A bale spear is coupled to the outer carrier plate via a linkage bar. The linkage bar is configured to move the bale spear relative to the outer carrier plate and the inner carrier plate between a retracted position and an extended position along a spear axis

Methodology Applied

Scientific EffectMechanical linkage motion:

Implementation Method 3

A push stroke latch system interconnects the frame, the inner carrier plate and the outer carrier plate. The push stroke latch system is configured to secure the outer carrier plate relative to the frame during an initial portion of the push stroke while allowing the inner carrier plate to move along the longitudinal axis in the first longitudinal direction during the initial portion of the push stroke

Methodology Applied

Scientific EffectMechanical latching:

Implementation Method 4

A return stroke latch system interconnects the frame, the inner carrier plate and the outer carrier plate. The return stroke latch system is configured to secure the outer carrier plate relative to the frame during an initial portion of the return stroke while allowing the inner carrier plate to move along the longitudinal axis in the second longitudinal direction during the initial portion of the return stroke

Methodology Applied

Scientific EffectMechanical latching:

Data Source

PatentEP4677994A1Bale ejection system for large square baler

Publication Date: 2026.01.14 DEERE & CO

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AI summary

A bale ejection system includes an outer carrier plate an inner carrier plate, and a linear actuator attached to the inner carrier plate. A bale spear is coupled to the outer carrier plate via a linkage bar. A return stroke latch system secures the outer carrier plate relative to the frame during an initial portion of a return stroke while allowing the inner carrier plate to move along a longitudinal axis in a second longitudinal direction during the initial portion of the return stroke, whereby the linkage bar moves the bale spear along a spear axis from an extended position into a retracted position for disengaging from the bale.