Mobile Crane Overload Protection via Dynamic Stability Calculation
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Solution Overview
Problem
Existing overload protection systems for mobile cranes are inefficient as they require separate limit curves or lifting capacity tables for every crane configuration and supporting position, making them costly and impractical, especially when space constraints lead to asymmetrical support geometries.
Innovation Solution
A mobile crane system that includes a memory unit for storing limit curves or values for various parameters, with means to monitor prop positions and calculate static stability, determining the tilting edge as a limit value, and using redundant control circuits to ensure safe operation by maintaining a safety distance from limit values in all degrees of freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate limit curves or lifting capacity tables are stored for every crane configuration and supporting position, then crane safety is ensured, but data storage requirements and cost increase significantly
Solution Approach 1:
The patent segments the limiting factors into distinct categories: individual component strength limits (boom, cables, cylinders) and global static stability limits. By separating these concerns, the system stores comprehensive safety data once rather than creating separate limit curves for every configuration combination, reducing overall data storage requirements while maintaining complete safety coverage.
Solution Approach 2:
The patent creates a universal evaluation framework that works across all crane configurations and supporting positions. Instead of storing configuration-specific limit curves, the system uses a single set of component strength values and stability criteria that can evaluate any configuration, making the safety system universally applicable and eliminating redundant data storage.
2Reliability
If traditional overload protection systems use fixed limit curves for symmetrical support positions, then safety is maintained, but operational flexibility is reduced when asymmetrical support is required
Solution Approach 1:
The patent implements a dynamic safety evaluation system that adapts to the actual supporting geometry in real-time. Instead of relying on fixed limit curves for predetermined symmetrical positions, the system dynamically calculates stability and strength limits based on the current prop positions and crane configuration, enabling safe operation in asymmetrical and unconventional supporting positions.
Solution Approach 2:
The patent changes the approach from using fixed geometric parameters (predetermined support positions) to using variable parameters (actual prop positions, center of gravity location, support forces). This allows the safety system to accommodate any supporting geometry by continuously evaluating the current state rather than relying on pre-defined configurations.
3Reliability
If limit curves are stored for all possible supporting positions including extendable props, then complete safety coverage is achieved, but the complexity and cost of the system increase
Solution Approach 1:
The patent extracts the essential safety criteria from complex configuration-specific limit curves. By identifying and storing only the fundamental component strength limits and stability principles, the system eliminates the need for extensive limit curve tables while maintaining complete safety coverage through direct evaluation of these extracted principles against actual operating conditions.
Data Source
AI summary
A mobile crane has at least one memory unit in which limit curves or limit values are stored for various crane parameters and which should not be exceeded, or only exceeded by issuing an alarm signal, to ensure safe operation of the crane. Crane safety is ensured by monitoring the individual limit values of the various parameters and checking the current position of the extendable and retractable props which serve to support the mobile crane. Depending upon the actual position the supporting cylinders reach, the tilting edge of the mobile crane is determined as a limit value. Furthermore, depending on the individual parameters of the mobile crane and the suspended load, whether the operating condition of the mobile crane lies within this limit value is determined.