Crane Guy Line Joint Positioning for Bending Moment Reduction
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Solution Overview
Problem
Conventional cranes face challenges in maintaining hoisting capacity when the boom is shortened, leading to increased bending moments and reduced capacity, and when lengthened, they require higher tensile forces to raise the boom, compromising efficiency.
Innovation Solution
A crane design featuring a guy line system with a joint and support device that allows the joint's position to be selectively changed along a perpendicular axis, optimizing the acting force's position relative to the boom axis, thereby reducing bending moments and tensile forces required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the boom is made shorter, then the hoisting capacity is improved by positioning the compressive force closer to the boom axis, but the angle between the pendant and boom axis decreases causing greater bending moments
Solution Approach 1:
The patent applies dynamics by making the joint position adjustable rather than fixed. The holding member can selectively position the joint at multiple locations along the boom, allowing the system to adapt its configuration based on operational requirements. This dynamic adjustment capability enables optimization of both hoisting capacity and bending moment reduction depending on the specific working conditions.
Solution Approach 2:
The patent changes the parameter of joint position along the boom axis. By providing multiple holding parts at different positions and allowing selective attachment of the joint to these holding parts, the system varies the position parameter to achieve different performance characteristics. This parameter change enables the boom to maintain optimal mechanical properties across different boom lengths and loading conditions.
2Adaptability or versatility
If the boom is made longer, then the versatility of the crane is improved, but the tensile force required to raise the boom increases
Solution Approach 1:
The adjustable joint position provides dynamic adaptability that compensates for the increased tensile force requirements of longer booms. By allowing the joint to be repositioned along the boom, the system can optimize the mechanical advantage and force distribution, thereby reducing the tensile force burden on the derricking mechanism while maintaining extended boom capability.
Solution Approach 2:
The patent changes the position parameter of the joint relative to the boom axis and derricking mechanism. This parameter adjustment optimizes the geometric relationship between the pendant, boom, and support structure, thereby reducing the tensile force component required to raise longer booms while maintaining the extended reach and versatility.
3Device complexity
If a fixed pendant link is used, then the structure is simple, but the hoisting capacity decreases when boom length is changed
Solution Approach 1:
The patent transitions from a fixed linking device to a dynamic one with adjustable joint positions. The holding member with multiple holding parts allows the joint to be repositioned along the boom, providing adaptability that maintains optimal hoisting capacity across different boom lengths while adding only moderate structural complexity.
Solution Approach 2:
The linking device is designed with multi-functionality through the holding member that can accommodate the joint at multiple positions. This universal design allows the same structure to serve different functional requirements for various boom lengths and hoisting conditions, eliminating the need for multiple specialized configurations.
Data Source
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AI summary
A crane comprises a boom (10) having a structure which allows the length of the boom to be changed, and a derricking mechanism (11) configured to rotate the boom (10) to raise and lower the boom with respect to a machine body, wherein: the derricking mechanism (11) includes a linking device (32) connecting one end of a guy line (30) to a distal end of the boom (10); the distal end (13) of the boom (10) has a back surface (21) which faces rearward and a ventral surface (22) which faces forward when the boom is in a vertical position; the linking device (32) includes a joint (36) connected to one end of the guy line (30), and a support device (38) provided on the distal end (13) to support the joint (36) so as to locate the joint (36) at a position away from the back surface (21) and opposite to the ventral surface(22); and the support device (38) includes a holding member (49) which holds the joint (36), the holding member (49) allowing the position of the joint to be selectively changed to a plurality of different positions in a first direction perpendicularly intersecting an axis of the boom and a rotary axis of the boom. The holding member (49) includes a plurality of holding parts (49a) respectively disposed at the different positions in the first direction (A), each of the holding parts (49a) being configured to detachably hold the joint (36). The support device (38) includes a supporting member (50) which is disposed between the holding member (49) and the back surface of the distal end. The supporting member (50) is coupled with the joint (36) held by the holding member (49) to support the holding member (49) at the position of the joint (36) via the joint (36).