Mobile Crane Boom Angle Control to Prevent Mast Collapse
Solution Overview
Problem
Mobile cranes with luffing jibs face damage during boom operations due to improper mast alignment, leading to the second mast falling and damaging the luffing jib, as existing methods lack effective control mechanisms to prevent excessive boom angles and rope lengths.
Innovation Solution
A mobile crane equipped with a control unit that monitors and controls the boom's angle and rope length, stopping the derrick cylinder or winch when maximum limits are reached to prevent the second mast from falling, and alerts operators to avoid damage, using a system of tension links, winches, and detectors to manage the luffing jib's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the boom is raised without sufficient mast rotation, then the boom can be raised quickly, but the second mast may fall down and damage the luffing jib
Solution Approach 1:
The control unit continuously monitors the rotation angles of the first and second masts through detectors, and based on this feedback information, dynamically controls the derrick cylinder to prevent the boom from being raised when mast rotation is insufficient, thereby avoiding mast collapse and luffing jib damage
Solution Approach 2:
The system requires the masts to be rotated to predetermined safe angles before allowing the boom raising operation to commence. The control unit checks mast rotation angles in advance and only permits boom elevation when the masts are properly positioned, preventing premature boom raising that could cause mast failure
2Device complexity
If manual monitoring of mast rotation angle is used, then the system remains simple, but operator error may cause excessive boom angle and mast failure
Solution Approach 1:
Detectors mounted on the masts provide continuous feedback information about rotation angles to the control unit, which automatically compares actual angles against safe operating limits and prevents boom raising when angles are insufficient, eliminating reliance on manual monitoring
Solution Approach 2:
The control system automatically monitors mast rotation angles and makes decisions about whether to permit boom raising operations without requiring operator intervention for angle assessment, making the system self-regulating and more reliable
Data Source
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AI summary
[Object] To provide a mobile crane configured so as to prevent breakage of a luffing jib during a derrick operation of a boom or the luffing jib. [Solution] A mobile crane (100) is configured so that a boom (22) is raised by a derrick cylinder (51) in response to a raise signal output from a derrick lever (55)(S22: Yes) (S23) and the derrick cylinder (51) is stopped in response to the derrick angle of the boom (22) reaching the maximum angle γ corresponding to the hoisted-down length of a rope (44)(S24: Yes) (S25).