Self-Engaging Roll-Off Container Locking System with Positive Unlocking
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Solution Overview
Problem
Existing roll-off container systems require operator intervention for locking and unlocking, leading to potential forgetfulness and subsequent damage during transport, especially over rough terrain.
Innovation Solution
A self-engaging locking system mounted to the hoist frame rail, utilizing a hook with a center of mass bias to automatically lock and unlock as the hoist frame rails are lowered and raised, with a mechanical unlocking mechanism to prevent binding and a keeper element to maintain contact over rough terrain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If operator-dependent locking systems (straps, chains, powered locks) are used, then containers can be secured during transport, but operators may forget to engage or disengage them, causing damage to container, hoist, or truck
Solution Approach 1:
The locking system automatically engages and disengages without operator intervention. The hook's center of mass creates automatic engagement when the rail is lowered, and the positive unlocking mechanism automatically disengages the hook when the rail is raised, eliminating the need for operator action and preventing forgetfulness-related damage
Solution Approach 2:
The system performs locking action in advance during the lowering process before transport begins, and automatically prepares for unloading by raising the rail to trigger automatic unlocking. This preliminary and automatic action sequence ensures locking is always engaged during transport without requiring operator memory or action
2Extent of automation
If the hook is biased to unlocked position by center of mass, then automatic unlocking occurs when rail is raised, but the hook may bind to the container during lifting
Solution Approach 1:
The positive unlocking mechanism applies a downward force on the hook before binding can occur during the lifting process. This preliminary counter-action prevents the harmful binding effect from taking place by actively pulling the hook away from the container frame member during the critical lifting phase
Solution Approach 2:
The pull-down device acts as an intermediary mechanism between the hook and the rail system. It provides the necessary downward force to prevent binding while allowing the hook's center of mass to continue providing automatic unlocking functionality, mediating between the conflicting requirements of automatic unlocking and binding prevention
3Strength
If the striker element is used to lock the hook, then secure locking is achieved, but the striker may fall out of contact with the hook on rough terrain
Solution Approach 1:
The keeper element provides continuous feedback by maintaining physical contact with the striker element. When the striker moves or risks losing contact (as on rough terrain), the keeper element's engagement ensures the striker remains positioned to maintain contact with the hook, providing real-time correction and maintaining reliable locking strength
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
Ensures secure and automatic locking and unlocking of roll-off containers without operator action, preventing damage and ensuring safety during transport, even on uneven surfaces.
Implementation Method 1
The hook has a center of mass located to bias the hook to an unlocked position
Implementation Method 2
A positive or mechanical unlocking mechanism is provided to prevent binding of the hook to the container during lifting of the container. The mechanism includes a pull down device that operates automatically to exert a downward force on a hook
Data Source
AI summary
A locking system for locking a container to a vehicle includes a locking assembly mounted to a hoist frame and a striker assembly mounted to the vehicle chassis. The locking assembly has at least one hook for hooking over a frame member of the container. The hook has a center of mass that biases the hook to an unlocked position. The striker assembly strikes the hook at a location to move the hook against the bias of the hook's center of mass into a locked position in which the hook is hooked over the frame member of the container. As the hoist frame supporting the container is lowered, the striker assembly contacts the hook and rotates the hook against the bias of the hook's center of mass into the locked position. As the hoist frame is raised, the hook rises as well and loses contact with the striker assembly, thereby falling away from the hoist frame and unlocking the container. A positive or mechanical unlocking mechanism prevents the hooks from binding to the container.