Fall Arrest Cart Spike Deployment Mechanism
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Solution Overview
Problem
Existing fall arrest carts for flat roofs often require an arm support and resistance force, which complicates the engagement mechanism and may not provide optimal protection, as the force required to engage the spike is greater when moving than when engaged, and they can damage the surface.
Innovation Solution
A mobile safety fall arrest cart with a spike assembly that moves between a stowed and deployed configuration, using a trigger assembly to deploy the spike upon a worker's fall, eliminating the need for an arm support and resistance force, and orienting the spike laterally to enhance protection and prevent surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an arm support and resistance force mechanism is used to control the engagement plate, then the cart can be selectively held in position, but the device complexity increases and the force required to engage the spike is greater when moving than when engaged
Solution Approach 1:
The patent removes the arm support and resistance force mechanism from the system, replacing it with a direct spike-to-surface engagement system. The trigger assembly directly controls the spike's movement between engaged and disengaged positions without intermediate mechanical supports or resistance mechanisms, thereby reducing device complexity while maintaining fall arrest reliability
Solution Approach 2:
Instead of using a mechanism that requires overcoming resistance force to engage (as in prior art), the invention inverts the approach by allowing the spike to engage the surface directly through gravitational force and the triggering mechanism. The force dynamics are reversed so that engagement occurs more easily when needed, rather than requiring excessive force during movement
2Reliability
If the engagement plate pivots down towards the elevated surface, then the cart can engage the surface, but the force required to engage is greater when moving and may damage the surface
Solution Approach 1:
The trigger assembly is designed to control the spike's engagement in advance, allowing the operator to selectively engage or disengage the spike before actual fall arrest is needed. This preliminary control mechanism ensures the spike engages the surface only when necessary and with controlled force, preventing unnecessary surface damage while maintaining reliable positioning
Solution Approach 2:
The invention changes the engagement parameters by using a trigger-based mechanical linkage system that controls the spike's movement. The trigger assembly modifies the force application parameters, allowing the spike to engage with appropriate force only when triggered, rather than continuously applying force that could damage the surface during normal operation
3Reliability
If the spike assembly is designed to penetrate the elevated surface, then fall arrest protection is improved, but the maneuverability of the cart is reduced
Solution Approach 1:
The spike assembly is designed as a dynamic component that can transition between two states: engaged with the surface (providing fall arrest protection) and disengaged (allowing free maneuverability). The trigger assembly enables the operator to dynamically switch between these states based on operational needs, combining both protection and mobility requirements
Solution Approach 2:
The cart system is segmented into independent functional components: the mobile cart body, the spike assembly, and the trigger assembly. This segmentation allows the spike assembly to operate independently - engaging or disengaging from the surface without affecting the cart's inherent maneuverability when disengaged, thus resolving the contradiction between protection and mobility
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 solution provides enhanced fall arrest protection by ensuring the spike engages the surface with maximum force during deployment, preventing cart movement and minimizing surface damage, while allowing easier maneuverability and increased safety for workers on flat elevated surfaces.
Implementation Method 1
The weight of the worker biases the spike assembly towards the deployed configuration
Implementation Method 2
A pulling force that is directly proportional to the weight of a person that has fallen and the velocity of the person's fall is excerpted on the arrestor arm
Data Source
AI summary
A mobile safety fall arrest cart is provided. The mobile safety fall arrest cart is configured to move along an edge of an elevated surface as a worker works along the edge. The worker is connected to the cart with a safety line. If the worker falls from the elevated surface, the weight of the worker causes a spike assembly to move from a stowed configuration to a deployed configuration. In the deployed configuration, a spike member engages the elevated surface so as to assist in arresting the worker's fall.