Rotatable Auxiliary Sheave Frame for Reduced Crane Structure Mass
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Solution Overview
Problem
Existing auxiliary sheave devices for cranes have complex structures and high masses, limiting the lifting capacity of the crane.
Innovation Solution
A crane with an auxiliary sheave device featuring a simple and lightweight structure, including an auxiliary sheave frame that is rotatably supported by a pair of supports and connected via guy lines to the boom, with backstops to prevent excessive rotation, allowing for efficient load cancellation and reduced structural reinforcement needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional auxiliary sheave device is fixed to the jib, then the auxiliary sheave can be supported, but the structure becomes complex and the mass increases
Solution Approach 1:
The auxiliary sheave device is divided into separate functional components: the auxiliary sheave itself, the auxiliary sheave guy line, and the auxiliary sheave frame. This segmentation allows each component to be optimized independently and simplifies the overall structure compared to a monolithic fixed mounting.
Solution Approach 2:
The auxiliary sheave frame is designed to be rotatable relative to the boom, transitioning between a projecting posture during operation and a retracted posture for storage or transport. This dynamic capability reduces structural complexity by eliminating the need for complex fixed mounting mechanisms.
2Reliability
If a conventional auxiliary sheave device is fixed to the jib, then the auxiliary sheave can be supported, but the mass becomes large
Solution Approach 1:
The auxiliary sheave frame's rotatability allows it to be positioned only when needed, reducing the effective mass that must be continuously supported by the boom. The frame can be rotated to a retracted position during transport or storage, minimizing the weight burden on the crane structure.
Solution Approach 2:
The auxiliary sheave frame utilizes thin-walled structural members and flexible guy lines to provide necessary support while minimizing mass. The rotational joints and thin-walled construction reduce the overall weight compared to conventional rigid fixed mountings.
3Productivity
If the auxiliary sheave frame is made lightweight, then the lifting capacity improves, but the structural strength may be reduced
Solution Approach 1:
The auxiliary sheave frame employs thin-walled structural members that provide adequate strength through optimized geometric design rather than material quantity. The thin-walled construction reduces mass while maintaining sufficient structural integrity for the intended loading conditions.
Solution Approach 2:
The rotational capability of the auxiliary sheave frame allows dynamic load distribution, where forces are managed through rotation rather than rigid resistance. This dynamic behavior enables lightweight construction by avoiding the need for heavy static structural reinforcement.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Provided is an auxiliary sheave device (50) with a simple and lightweight structure and a crane (1) including the same. The auxiliary sheave device (50), provided in the crane (1) including a derrick member guy line (45), includes an auxiliary sheave frame (51) and an auxiliary sheave guy line (55) supporting the auxiliary sheave (61). The derrick member guy line (45) is connected to the distal end portion of the derrick member (20). The auxiliary sheave frame (51) is attached to the distal end portion of the derrick member (20) so as to be capable of making rotational movement and taking a projecting posture of projecting in the distal end direction from the distal end portion of the derrick member (20). The auxiliary sheave guy line (55) is connected to the distal end portion of the auxiliary sheave frame (51) and a guy line connection portion (23) of the derrick member (20) so as to keep the auxiliary sheave frame (51) in the projecting posture.