Ring Derrick Stationary Counterweight Extraction
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Solution Overview
Problem
Existing construction crawler cranes face limitations in load moment capacity, ground bearing pressure, and wind tolerance, which affect their stability, safety, and productivity, particularly due to the need for pile-supported foundations and low wind tolerance.
Innovation Solution
A ring derrick design where the counterweight is stationary, either above ground or below grade, allowing the derrick to focus solely on lifting loads without supporting the counterweight, and featuring an A-frame construction and a tension column to manage loads and wind forces, enabling greater lifting capacity and reduced ground pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the derrick carries the counterweight on its structure, then the counterweight provides balancing force, but the ground bearing pressure increases and stability deteriorates
Solution Approach 1:
The counterweight is extracted from the derrick structure and placed on the ground separately. The derrick carriage no longer carries the counterweight, eliminating the adverse effect of increased ground bearing pressure while the counterweight remains in place to provide the necessary balancing force for the boom and load.
2Strength
If the derrick structure supports both the boom and counterweight, then the structure must be stronger, but the ground bearing pressure increases requiring pile-supported foundations
Solution Approach 1:
The counterweight is extracted from the derrick structure and placed independently on the ground. This separation allows the derrick structure to be optimized for boom support only, reducing the required structural strength and eliminating the need for complex pile-supported foundations.
3Force
If conventional cranes are used to achieve greater load moment capacity, then lifting capacity increases, but ground bearing pressure and wind tolerance problems persist
Solution Approach 1:
The counterweight is extracted from the mobile crane structure and placed as a stationary element on the ground. This allows the derrick to achieve greater load moment capacity through the tension column and stationary counterweight arrangement, while the carriage remains light and generates minimal ground bearing pressure.
4Force
If the counterweight is above ground, then it provides balancing force, but it obstructs movement of the derrick and other vehicles
Solution Approach 1:
Instead of placing the counterweight above ground level, the counterweight is inverted and placed below ground level in a pit. This allows vehicles to drive over the counterweight location without obstruction while the counterweight remains in place to provide the necessary balancing force through the tension column.
Data Source
AI summary
A ring derrick includes a carriage which moves on a fixed circular track around a stationary counterweight. A tension and compression column assembled from transportable tubular segments is affixed to the counterweight by a universal swivel joint. The back mast of the derrick is secured at its upper end to the tension column, while the main boom of the derrick extends radially away from the tension column. The main boom and back mast are hinged directly together at the carriage by massive hinge pins which pass through spherical bearings mounted on the carriage. The carriage's suspension distributes the load from the boom and mast to an array of trucks and has an automatic stabilizing system that compensates for uneven track.