Overload Protection for Crane Hoisting Drives
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Solution Overview
Problem
Existing overload protection systems for cranes and container bridges are complex and expensive, particularly in container bridges where snag-overload systems require synchronized hydraulically controlled sliding clamps, leading to maintenance challenges and potential structural failures due to overloading.
Innovation Solution
A control and regulation arrangement with sensors detecting overload and speed, activating brake equipment to block movement and allow controlled lowering, using redundant safety components and electrohydraulic compressed air systems for reliable operation, and including a frequency-controlled brake system for precise speed regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulically controlled sliding clamps are used for snag-overload protection, then overload protection reliability is improved, but device complexity and maintenance requirements increase significantly
Solution Approach 1:
The patent extracts the complex hydraulic control system and replaces it with a simpler mechanical overload coupling device that automatically disconnects the drive train from the hoisting drum when overload occurs. This removes the need for hydraulically controlled sliding clamps and their associated complexity while maintaining protection functionality.
Solution Approach 2:
The overload coupling device is designed to automatically detect and respond to overload conditions without requiring external hydraulic control systems. The device self-activates when the coupling torque exceeds the predetermined threshold, eliminating the need for complex control mechanisms.
2Reliability
If synchronized hoisting cables with snag-overload systems are used in container bridges, then safety is improved, but cost and maintenance requirements increase
Solution Approach 1:
The patent applies the same simple overload coupling principle to both hoisting cables in the container bridge system. This universal application of a single, simple device type reduces manufacturing costs compared to complex synchronized hydraulic systems, while maintaining safety through redundant protection on both cables.
3Reliability
If brake equipment is used to block transport during overload, then protection is improved, but control system complexity increases
Solution Approach 1:
The patent combines the overload detection function and the braking function into a single integrated control mechanism. The overload coupling directly triggers the brake activation without requiring separate sensors, signal processing systems, and control logic, thereby reducing overall control system complexity while maintaining protection reliability.
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
This solution simplifies overload protection by ensuring reliable detection and management of overloads, reducing maintenance needs and preventing structural damage, while allowing safe and controlled vertical transport with minimal disturbance to the load.
Implementation Method 1
brake equipment (3, 3') which acts upon an object in transport (16)
Implementation Method 2
electrohydraulic compressed air systems for reliable operation
Data Source
AI summary
A control and regulation arrangement for protection of a conveyor or other hoisting or crane device that assures a safe reaction to overloading. A brake apparatus is provided that acts on the conveyor under control of an overload sensor. If the load approaches a predetermined threshold, a signal is emitted from the overload sensor and transmitted to a speed sensor that limits the conveyor speed. Simultaneously the control transmits a signal to the brake apparatus to actuate and stop the conveyor. Upon receipt of a subsequent signal that a load relief state is to be established, the control brakes the conveyor in accord with the speed signal such that the object in transport moves toward a safe position at a constant speed. A conveyor with multiple hoisting devices may include duplicate control and regulation arrangements for each hoisting device.