Shiftable Jib Mast for Easier Crane Support Rope Removal
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Solution Overview
Problem
Existing cranes impose a significant burden on workers during the installation and removal of jib and boom-side support ropes due to the heavy weight and tensioning requirements, particularly in connecting and detaching the rear jib pendant rope to/from the boom.
Innovation Solution
A crane design featuring a jib posture retention device with a jib-side and boom-side support ropes, a rope connection part, and a shiftable jib mast that allows for easy installation and removal of support ropes by shifting between tension and looseness positions, reducing the physical effort required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rear jib pendant rope is tensioned between the boom and the distal end of the jib mast to retain the jib in a predetermined frontward tilt posture, then the jib can be retained in the predetermined frontward tilt posture with respect to the boom, but the burden on a worker in the work of installing and removing the rear jib pendant rope becomes very large
Solution Approach 1:
The jib mast is made shiftable between a first position (for tensioning the support rope) and a second position (for easy removal). This dynamic repositioning allows the system to transition between operational states, enabling simple rope removal while maintaining reliable posture retention during crane operation.
Solution Approach 2:
The proximal end of the jib mast acts as an intermediary element that can be repositioned to facilitate rope removal. By shifting the jib mast to the second position, the proximal end moves to an accessible location where the support rope can be easily detached, without requiring workers to handle heavily tensioned ropes.
2Ease of manufacture
If the connection pin is extracted from the rope connection place to remove the rear jib pendant rope, then the rope can be removed, but the tension on the connection pin must be released first by pulling the rear jib pendant rope, which requires large labor
Solution Approach 1:
The jib mast's ability to shift positions dynamically changes the tension state of the support rope. When moved to the second position, the geometry of the system naturally reduces tension, allowing the connection pin to be extracted without requiring workers to pull against high tension forces.
Solution Approach 2:
The jib mast is shifted to the second position before attempting to remove the support rope. This preliminary repositioning action prepares the system by reducing rope tension and making the connection pin accessible, thereby facilitating easy rope removal without excessive labor.
3Reliability
If the boom is raised to render the pendant rope linearly tensioned between the distal end of the jib mast and the distal end of the jib, then the jib can be supported in the predetermined frontward tilt posture, but the physical effort required to install and remove the support rope increases significantly
Solution Approach 1:
The system uses dynamic repositioning of the jib mast rather than maintaining a fixed high-tension configuration. During installation and removal operations, the jib mast is positioned in the second position where gravity and geometry naturally reduce rope tension, making manual handling feasible while still achieving reliable support when in the operational first position.
Solution Approach 2:
The jib mast is repositioned to the second position as a preliminary step before support rope installation or removal. This preliminary action creates favorable conditions by reducing tension and improving accessibility, allowing workers to perform rope operations with minimal physical effort before the system transitions to its load-bearing configuration.
Data Source
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AI summary
A crane includes a jib posture retention device that retains in a predetermined frontward tilt posture to a boom. The jib posture retention device includes a jib mast that holds a rope connection part at a tensioning position separate from proximal end and a boom distal end backward thereof to render a jib-side support rope and a boom-side support rope linearly tensioned with the jib in the frontward tilt posture. The jib mast is configured to be shiftable to a tension form of holding the rope connection part at a tensioning position in an uprise posture and a looseness allowing form of locating the rope connection part at a looseness allowing position closer to the boom distal end than the tensioning position and closer to the jib proximal end than the tensioning position to allow the jib-side support rope and the boom-side support rope to be loosened.