Adjustable Locking Device for Lawn Mower Cutting Plate

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Solution Overview

Problem

Existing locking/releasing devices for cutting plates on lawn tractors are not adjustable and lack safety features to maintain partial lock in case of failure, limiting their flexibility and user safety.

Innovation Solution

A locking/releasing device with an L-shaped bar featuring multiple adjustment holes and a safety hole, combined with a bushing, spiral spring, and safety pin, allowing for adjustable locking positions and ensuring the cutting plate can be lifted safely while maintaining integral connection, with components easily assembled and lightweight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single locking position pivot is used, then the device structure is simple, but the adaptability to different tractor models and applications is limited

Engineering Contradiction:
Improveadjustability to different tractor modelsVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The bar is segmented with multiple adjustment holes at different positions along its length. This allows the bushing to be locked at various positions by aligning holes with corresponding features on the tractor, providing adaptability to different models without requiring multiple different bar designs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bar serves multiple functions: it provides structural support, enables adjustable positioning through multiple holes, and works with the safety pin mechanism. This multi-functionality allows a single component design to adapt to various tractor models and applications.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If no safety means are provided, then the device structure is simpler, but the reliability in case of breaking is compromised

Engineering Contradiction:
Improvesafety in case of breakingVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The safety pin is positioned to engage with the bushing and bar structure in advance, creating a backup locking mechanism. In the event of breaking or failure of the primary spring-based locking system, the safety pin maintains the locked position, preventing accidental release and ensuring continued safety.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If the cutting plate is lifted by gripping at the front part, then the cutting area becomes accessible, but the operator may lose control of the plate

Engineering Contradiction:
Improveaccessibility of cutting areaVSAvoidcontrol of cutting plate
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The locking/releasing device acts as an intermediary between the cutting plate and the tractor frame. The bushing, bar, and safety pin mechanism provide a controlled interface that allows the plate to be safely positioned and locked at inclined angles for cleaning, while maintaining secure attachment to the tractor.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables flexible use across various tractor models, ensures user safety by allowing multiple locking positions and maintaining the cutting plate in a predetermined position, with enhanced safety features preventing accidental unthreading and partial lock in case of failure.

Implementation Method 1

a spiral spring (24)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a safety pin (30) inserted into a safety hole (111) of the bar (10)

Methodology Applied
Scientific EffectMechanical Fastener: Mechanical Fastener

Data Source

PatentEP3504953B1A manual locking/releasing device for a cutting plate
Publication Date: 2020.05.27 STIGA S P A IN BREVE ANCHE ST SPA
  • EP3504953B1 patent drawingFigure 1~2
  • EP3504953B1 patent drawingFigure 3~4
  • EP3504953B1 patent drawingFigure 5~6

AI summary

A locking/releasing device (9) for a cutting plate (2) of a lawn mower (1) is described. Said device (9) comprises a bar (10) having through-holes (11, 111) and a bushing (15) provided with a cavity (16) closed at a head (18) of the bushing (15) and which develops from a mouth (17) opposite to said head (18) with respect to a longitudinal axis (P) of the bushing (15). Said bar (10) is adapted to be partially inserted into said cavity (16) of the bushing (15).