Mechanical Overload Protection for Cable Strands
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Solution Overview
Problem
Existing overload protection systems for cranes only account for loads hanging from the crane and do not effectively prevent damage when the drive systems are shut down, as they fail to relieve the crane structure of excessive loads, leading to potential damage from overloading.
Innovation Solution
A mechanical overload protection device integrated into the cable line or at the cable fixing point that extends the cable length when the permissible tension force is exceeded, relieving the load from the crane structure and triggering a shutdown signal when the maximum load is reached, combining with electronic overload safety means to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electronic overload safety means are used to switch off crane operation when permissible load is exceeded, then crane operation safety is improved, but the crane structure can still be damaged by overload hanging from the crane when drive systems are shut down
Solution Approach 1:
A mechanical overload protection device is introduced as an intermediary between the cable line and the crane structure. This device includes a load pin with a piston that can slide within a housing, acting as a mechanical mediator to relieve excessive loads from the crane structure by allowing controlled cable extension when tension exceeds permissible limits
Solution Approach 2:
The patent replaces reliance solely on electronic overload safety means with a mechanical overload protection device that operates independently of electronic systems. The mechanical device uses a stroke force limiting device with spring-loaded balls or components that physically engage and disengage based on load conditions, providing fail-safe mechanical protection against overload damage
2Object-affected harmful factors
If a mechanical overload protection device is added to relieve load from crane structure, then protection against overload damage is improved, but device complexity increases
Solution Approach 1:
The mechanical overload protection device is integrated into the existing cable line system at the cable fixing point on the crane. The load pin is incorporated into the cable attachment mechanism, merging the overload protection function with the existing cable fixing structure rather than adding a completely separate system
Solution Approach 2:
The mechanical overload protection device operates autonomously based on the physical load conditions. The spring-loaded balls or components automatically engage or disengage the load pin from the housing based on whether the cable tension exceeds permissible limits, without requiring external control systems or human intervention
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 mechanical overload protection device effectively relieves the crane structure of excessive loads by increasing cable length, preventing damage and ensuring safe operation by shutting down the crane when overloads are detected, thereby protecting the crane components from permanent damage.
Implementation Method 1
a compression spring (19) is arranged between the nut (12) arranged closer to the closed side (4) of the interior (3) of the housing (2) and the piston (7) of the load pin (5)
Data Source
AI summary
An overload protection device for cable lines, and in particular in cranes, is provided, having at least one electronic overload safety means. The overload protection device is provided to prevent any kind of damage which can be caused by an overload. That is achieved by providing a mechanical or magnetic overload protection device (1) in addition to the electronic overload safety means. The overload protection device (1) is integrated into the cable line or arranged at the cable fixing point and responds when a permissible cable tension force is exceeded and implements a cable extension.