Offset Mast Stacker Crane for Watercraft Stability

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Solution Overview

Problem

Conventional watercraft storage cranes with central masts are unstable and require over-engineering due to eccentric load moments, straining bridge girders and experiencing frequent system failures, as they are not designed to accommodate varying boat center of gravities within their footprint.

Innovation Solution

A watercraft storage stacker crane system with a rotatable and offset mast, featuring a larger diameter turntable positioned above the trolley with a thrust bearing, and an offset mast that extends below the bridge girders, ensuring the center of gravity remains within the support footprint for balanced operation and reduced angular momentum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a central mast is used in conventional stacker cranes, then the structure is simpler and easier to manufacture, but the system becomes unstable and requires over-engineering to handle eccentric load moments

Engineering Contradiction:

Improvemast structure simplicityVSAvoidsystem stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by offsetting the mast from the center of the turntable. The mast is positioned at a distance from the center of gravity of the turntable, creating an asymmetric configuration that allows the center of gravity of the entire system (turntable + mast + hoist + watercraft) to remain within the support footprint. This asymmetric positioning eliminates eccentric load moments and provides inherent stability without requiring over-engineering of the mast structure.

Inventive Principle:

Principle #4Asymmetry

2Device complexity

If the turntable footprint is kept small, then the device complexity is reduced, but it cannot accommodate a wide range of loads and varying center of gravities

Engineering Contradiction:

Improveturntable sizeVSAvoidload accommodation range

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent uses the offset mast and hoist positioning as a counterbalancing mechanism. By positioning the mast and hoist at specific offset distances from the turntable center, the system creates a counterbalancing effect that keeps the overall center of gravity within the support footprint. This allows a compact turntable design to accommodate various watercraft loads with different center of gravities without requiring an oversized turntable.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Stability of the object's composition

If the mast is made excessively heavy to compensate for center of gravity movement, then system stability is improved, but the cost and weight of the crane increase

Engineering Contradiction:

Improvecrane stabilityVSAvoidmast and crane weight

Core Design Contradiction:

Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The asymmetric offset configuration of the mast and hoist creates a natural counterbalancing effect that maintains stability without requiring excessive mast weight. The offset distance is specifically designed so that the center of gravity of the turntable-mast-hoist assembly remains within the support footprint, providing inherent stability that eliminates the need for over-engineering the mast with additional weight.

Inventive Principle:

Principle #4Asymmetry

4Adaptability or versatility

If conventional stacker cranes are used with boats that pull center of gravity outside the bridge girder footprint, then the system can handle larger boats, but undue strain is placed on bridge girders or the assembly may overturn

Engineering Contradiction:

Improveboat size capabilityVSAvoidbridge girder load capacity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The offset mast and hoist positioning creates a counterbalancing effect that ensures the center of gravity of the entire system remains within the bridge girder footprint even when handling large watercraft. This counterbalancing mechanism prevents undue strain on the bridge girders and eliminates the risk of assembly overturning, allowing the system to handle larger boats safely.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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 maintains stability and reduces maintenance needs by balancing the crane's center of gravity within the support footprint, allowing for higher rotational speeds and minimizing strain on bridge girders, thus reducing costs and system failures.

Implementation Method 1

The rotating turntable is located above the trolley and is supported by the trolley from below with a thrust bearing

Methodology Applied

Scientific EffectThrust bearing: Ball Bearing

Implementation Method 2

ensuring the center of gravity remains within the support footprint for balanced operation and reduced angular momentum

Methodology Applied

Scientific EffectAngular momentum: Angular Momentum

Data Source

PatentUS9745033B1Boat storage stacker with rotatable and offset mast

Publication Date: 2017.08.29 MAFFETT BRIAN

AI summary

Disclosed herein is a watercraft storage stacker crane system that incorporates an offset mast.