Spreader Frame Twist Lock Security Housing
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Solution Overview
Problem
Existing spreader frames for hoisting cargo containers face issues such as unintentional twist lock rotation, excessive bending stress, and horizontal force application, which can lead to container damage and safety risks, especially when handling loaded containers with uneven weight distribution or during transfer between vessels and platforms.
Innovation Solution
The improved spreader frame design incorporates a rigid frame structure with security housings and twist locks that require deliberate tool use for locking and unlocking, ensuring only vertical forces are applied to the container, and includes visual indicia for secure locking status, preventing accidental twist lock rotation and distributing forces to absorb horizontal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If general purpose hoist equipment is used to handle containers, then versatility is improved, but safety deteriorates due to risk of container damage and personnel injury
Solution Approach 1:
The spreader frame acts as an intermediary device between the hoist equipment and the container. It includes twist locks that engage with the container's lifting blocks, providing a secure connection that prevents direct harmful contact between the hoist and container. The spreader frame absorbs and distributes forces, protecting the container from damage while maintaining safety during handling operations.
2Ease of operation
If twist locks are made easily accessible for operation, then ease of operation is improved, but reliability deteriorates due to risk of unintentional rotation
Solution Approach 1:
The twist lock is nested within a security housing that provides protection and controlled access. The housing contains the twist lock mechanism and requires deliberate action (such as removing a cover or using a tool) to access the lock. This nesting structure prevents accidental rotation while still allowing authorized personnel to easily operate the lock when needed.
Solution Approach 2:
The security housing includes features such as covers or shields that preliminarily prevent access to the twist lock mechanism. These protective elements must be deliberately removed or opened before the twist lock can be operated, creating a preliminary barrier against unintentional rotation while maintaining ease of operation for authorized users.
3Device complexity
If direct attachment of container to hoist is used, then device complexity is reduced, but harmful factors increase due to excessive bending stress and horizontal forces
Solution Approach 1:
The spreader frame serves as an intermediary structure that distributes loads from the hoist to multiple points on the container. Instead of applying force directly to a single location, the frame's rigid structure and multiple twist locks spread the vertical and horizontal forces across the container's lifting blocks, reducing bending stress and preventing damage.
Data Source
AI summary
In embodiments, a spreader frame for hoisting a container having a lifting block is provided which includes a rigid frame structure, a twist lock received by the rigid frame structure, the twist lock being rotated relative to the rigid frame structure between a locked position to engage the lifting block and an unlocked position to disengage from the lifting block, and a safety feature which cooperates with at least one of the rigid frame structure and the twist lock to retain the twist lock in the locked position from being rotated relative to the rigid frame structure absent personnel changing a position of the safety feature.