Tower Crane Telescoping Mast Winch Mechanism
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Solution Overview
Problem
Existing self-erecting tower cranes with telescopic masts face challenges in deploying the mast to the desired height, particularly when inserting mast extensions, due to variations in cable length and issues with maintaining horizontality of the jib during telescoping.
Innovation Solution
A self-erecting tower crane design featuring a winch mechanism with a telescoping drum and a retaining drum mounted on the same drive shaft, allowing simultaneous rotation for telescoping or separation for inserting mast extensions, utilizing a geared motor with brake and auxiliary motor for precise control of the telescoping process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the telescoping drum and retaining drum are mounted on the same drive shaft for simultaneous rotation, then the mast can be telescoped efficiently, but mast extensions cannot be inserted
Solution Approach 1:
The drive shaft system is designed to be dynamically reconfigurable between two operational modes: simultaneous rotation of both drums for mast telescoping, and independent rotation of the telescoping drum alone for mast extension insertion. This dynamic adaptability allows the crane to switch between different operational requirements without structural modification.
Solution Approach 2:
The drive mechanism is segmented into two independent drive paths: one for the telescoping drum and one for the retaining drum. This segmentation allows each drum to be controlled independently, enabling the system to perform either mast telescoping or mast extension insertion operations as needed.
2Adaptability or versatility
If the telescoping drum and retaining drum are separated for mast extension insertion, then mast extensions can be inserted, but mast telescoping efficiency is reduced
Solution Approach 1:
The system dynamically reconfigures the drive shaft connections based on the operational mode. During mast extension insertion, the telescoping drum is connected to the drive shaft while the retaining drum is disconnected, allowing independent control. During mast telescoping, both drums are connected to the drive shaft for simultaneous rotation, maximizing efficiency.
Solution Approach 2:
The drive mechanism is divided into separate controllable units with independent drive paths. This segmentation enables selective activation of each drum's drive, allowing the system to optimize performance for specific operations rather than being constrained by a fixed simultaneous operation mode.
3Device complexity
If cable length variations are not compensated, then the structure is simpler, but the jib position becomes unstable
Solution Approach 1:
The system incorporates a feedback mechanism where the actual position of the jib is continuously monitored and compared with the desired horizontal position. Based on this feedback, the retaining drum is adjusted to compensate for cable length variations, ensuring the jib remains substantially horizontal throughout the telescoping operation.
Solution Approach 2:
The retaining drum automatically adjusts its rotation to compensate for cable length changes during telescoping. The system self-regulates the retaining cable tension and position without external intervention, maintaining jib horizontality through the inherent interaction between the two drum systems.
Data Source
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AI summary
The crane has a jib in horizontal position or folded along a telescopic mast. A winch mechanism (20) winds a telescoping cable, and has a retaining drum (16) associated to a telescoping drum (13) for unwinding a retaining cable. The drums are mounted and motorized so as to be simultaneously driven in rotation for telescoping the mast or disintegrated from each other for stopping the drum (16) and rotating the drum (13) to insert a mast extension bar at a base of the mast and to load the bar by an upper mast element or another mast extension bar.