Universal Roll-off Frame with Adjustable Head and Cable Hoist
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Solution Overview
Problem
Existing roll-off transport vehicles face challenges in handling containers of different lengths due to unintended loading conditions caused by variations in the center of gravity, and existing locking mechanisms are either complex or prone to jamming with moisture and debris.
Innovation Solution
A roll-off vehicle apparatus with a top frame that includes a main portion and a movably connected head portion, a cable hoist mechanism with sheaves, and a lockdown mechanism that automatically engages and disengages based on the top frame's position, allowing for efficient loading and unloading of containers of various sizes without complex hydraulic circuits or spring mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-length top frame is used, then the cable hoist mechanism can be simplified, but the vehicle cannot handle containers of different lengths without unintended loading conditions
Solution Approach 1:
The top frame transitions from a fixed-length structure to a dynamically adjustable structure. The head portion can be displaced longitudinally relative to the main portion through a movable connection mechanism, allowing the effective length of the top frame to change based on container size requirements. This dynamic adjustment capability enables the vehicle to handle containers of various lengths while maintaining proper loading conditions.
2Reliability
If a complex locking mechanism is used to secure containers, then containers can be securely locked, but the mechanism is prone to jamming with moisture and debris
Solution Approach 1:
The locking function is extracted from complex spring-based or multi-component mechanisms and simplified to a gravity-dependent gate member design. The gate member utilizes the gravitational force acting on the container itself to achieve secure engagement, eliminating the need for complex locking components that are susceptible to jamming from environmental contaminants.
Solution Approach 2:
The container's own weight and position serve as the locking mechanism. When the container is properly positioned on the top frame, gravity causes the gate member to engage automatically, securing the container without requiring external power sources, springs, or complex actuating mechanisms that could fail due to moisture or debris.
3Extent of automation
If spring mechanisms are used in the locking system, then automatic engagement is achieved, but the springs are prone to corrosion and failure from moisture exposure
Solution Approach 1:
Spring-based mechanical systems are replaced with a gravity-based passive mechanism. The gate member's engagement and disengagement are controlled by the container's position and gravitational force rather than elastic deformation of springs. This substitution eliminates corrosion-prone spring components while maintaining automatic engagement functionality.
4Adaptability or versatility
If multiple hydraulic actuators are used to adjust the top frame length, then containers of various lengths can be accommodated, but the hydraulic circuit becomes complex
Solution Approach 1:
The hydraulic actuation system is extracted and replaced with a simpler mechanical displacement mechanism. The head portion's longitudinal movement is achieved through a mechanical connection that allows relative motion without requiring hydraulic pressure control, thereby eliminating the need for complex hydraulic circuits while maintaining the ability to adjust to different container lengths.
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 safe and efficient loading and unloading of containers of various sizes by providing a mechanical advantage in the cable hoist and ensuring secure engagement of containers through the lockdown mechanism, avoiding issues of jamming and complex hydraulic systems.
Implementation Method 1
The top frame may incorporate a cable hoist mechanism having a set of sheaves and a cable wound around the sheaves
Implementation Method 2
The top frame may be tilted by one or more lift actuators, for example hydraulically powered linear actuators
Implementation Method 3
The top frame is pivotally mounted to be tilted away from a horizontal home position such that the top frame is inclined toward a rear of the vehicle to assist in loading and unloading the container
Data Source
AI summary
An apparatus for loading and unloading containers of various sizes onto and off of a roll-off vehicle comprises a top frame and at least one lift actuator operable to pivot the top frame away from a horizontal home position to rearwardly incline the top frame. The top frame includes a main portion, a head portion longitudinally displaceable relative to the main portion, a plurality of sheaves, a cable extending through the sheaves, and a hoist actuator operable to displace the head portion between a retracted position and an extended position. The cable has a fixed end coupled to the head portion and a free end for coupling to a container. The hoist actuator is operated while the top frame is away from the home position to displace the head portion toward the extended position to load a container onto the vehicle, and toward the retracted position to unload the container.