Lifeboat Hook Assemblies with Cam-Actuated Release Mechanism

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing lifeboat suspension systems with hook assemblies are prone to unintended or accidental release, especially under full load, leading to safety risks and discouragement of emergency drills due to the potential for serious accidents and fatalities.

Innovation Solution

A suspension system featuring load over centre hook assemblies with a dual release mechanism: a primary release mechanism for no-load conditions and an emergency release mechanism with high mechanical advantage for loaded conditions, ensuring safe and controlled operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hydrostatic interlock valve (hydrostat) is used to prevent inadvertent opening, then reliability improves, but device complexity increases and ease of operation deteriorates under emergency conditions

Engineering Contradiction:

Improveprevention of inadvertent openingVSAvoidcomplexity of locking mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the hydrostatic interlock valve (hydrostat) from the system and replaces it with a purely mechanical solution. The cam mechanism and spring are separate, simple mechanical components that eliminate the need for complex hydraulic systems while maintaining reliability in preventing inadvertent opening.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the hydrostatic (hydraulic) interlock valve with a mechanical cam and spring system. This substitution simplifies the device by eliminating complex fluid-based mechanisms in favor of straightforward mechanical components that are easier to maintain and operate.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a load over centre hook assembly is used to eliminate opening couple, then reliability improves, but force required to open under load increases significantly

Engineering Contradiction:

Improveprevention of accidental releaseVSAvoidforce to open hook under load

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

Instead of designing the hook to resist opening forces (load over centre design), the patent inverts the approach by using a cam mechanism that is designed to be easily overridden. The cam allows the hook to remain closed under normal conditions but can be intentionally opened by applying force in the opposite direction through the release cable, making emergency operation feasible.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces a cam mechanism as an intermediary between the load-bearing hook and the release cable. This cam acts as a mediator that translates the high force required to open a load-over-centre hook into a more manageable force applied through the release cable, while still maintaining secure closure under normal conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If a pivoted hook member with opening couple design is used, then ease of operation improves, but reliability deteriorates due to unintended release under load

Engineering Contradiction:

Improveease of hook releaseVSAvoidprevention of unintended release

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by using a cam mechanism that pre-resists the opening motion of the hook under load. The cam is positioned and shaped to counteract the opening couple generated by the load, preventing unintended release. The spring provides continuous pre-loading to maintain the closed position until a deliberate release action is taken.

Inventive Principle:

Principle #9Preliminary anti-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

Prevents inadvertent opening of hook assemblies under load while allowing controlled release under emergency conditions, enhancing safety and reliability of lifeboat operations.

Implementation Method 1

a spring engaged with the cam and arranged to bias the cam towards the hook-closed position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a cam for controlling the locking and release of the hook member

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Implementation Method 3

a release cable connected to the cam and arranged to pivot the cam when pulled, thereby releasing the hook member from the lifting link

Methodology Applied

Scientific EffectTension: Tension

Data Source

PatentUS9021977B2Lifeboat suspension system

Publication Date: 2015.05.05 SURVIVAL SYSTEMS INTERNATIONAL INC

AI summary

A suspension system for a lifeboat comprises a pair of hook assemblies adapted for connection at spaced locations to a lifeboat and for coupling respectively to a pair of suspension cables, each hook assembly comprising a hook member pivoted for movement about a pivotal axis between a closed setting where the line of action of a load on the hook member when in use passes substantially through the pivotal axis thereof and an open setting where an associated suspension cable is released from the hook member, each hook assembly further comprising an internal safety system that prevents the hook member from opening inadvertently; and a control mechanism for the pair of hook assemblies.