Crane Bracing Frame Traction Element Cable Wear
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Solution Overview
Problem
Lattice boom cranes experience cable wear and damage due to insufficient tractive force during the winding process, particularly at crossing points, leading to premature cable discard, as the existing bracing system does not maintain adequate lateral pressure stability during the tensioning and lifting phases.
Innovation Solution
A mobile lattice boom crane equipped with a variable-length traction element that articulates between the bracing frame and the boom, providing additional tractive force to increase the lateral pressure stability of cable windings, and a control unit to manage the tractive force dynamically, ensuring sufficient pre-tensioning during the tensioning phase and reducing it when the boom's weight takes over.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bracing cable is wound onto the cable winch during the tensioning phase, then the bracing frame is pivoted back and the bracing is tensioned, but the tractive force is insufficient causing cable damage at crossing points
Solution Approach 1:
The method applies preliminary action by tensioning the bracing before the main lifting operation. The bracing is pre-tensioned by pivoting the bracing frame back while the boom is still supported, creating initial stability. This preliminary tensioning prepares the system for the subsequent lifting phase without subjecting the cable to excessive loads during the critical setup phase.
Solution Approach 2:
The system dynamically adjusts the tractive force by controlling the cable winch operation in two distinct phases: first at reduced force during tensioning, then at higher force during lifting. The cable winch speed and torque are dynamically regulated based on the operational phase, allowing adequate force application while preventing cable damage during the vulnerable tensioning phase.
2Ease of operation
If the boom is tilted up by winding the bracing cable, then the boom reaches the desired angle, but cable wear increases due to lateral pressure at crossing points
Solution Approach 1:
The method performs preliminary bracing tensioning before the main boom lifting operation. By establishing the bracing configuration and initial tension in advance, the system prepares the load path so that when the boom is subsequently lifted, the forces are distributed more evenly and cable wear is minimized.
Solution Approach 2:
The lifting operation is divided into periodic phases: first the bracing is tensioned in a controlled manner, then the boom is lifted in stages. The cable winch operates in discrete operational modes corresponding to different phases of the lifting sequence, allowing the system to manage cable loads periodically rather than continuously at maximum stress.
3Strength
If the bracing frame is pivoted back to tension the bracing, then the bracing angle increases and leverage improves, but the cable is subjected to excessive transverse forces
Solution Approach 1:
The bracing frame is pivoted back in a preliminary phase to establish the optimal bracing angle and leverage configuration before the main lifting load is applied. This preliminary positioning allows the bracing to be properly configured so that subsequent lifting forces are transmitted more efficiently through the tension rods rather than creating excessive transverse cable loads.
Solution Approach 2:
The method maintains continuous useful action by keeping the cable under controlled tension throughout the entire operation. Rather than allowing the cable to go slack and then suddenly load it, the system maintains steady, manageable tension levels during bracing configuration, then smoothly transitions to the lifting phase, avoiding shock loads and excessive transverse forces.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces cable wear and extends the lifespan of the crane's cables by maintaining higher lateral pressure stability during the tensioning and lifting phases, ensuring the cables are not subjected to excessive transverse forces, thereby minimizing damage and prolonging their service life.
Implementation Method 1
the cable runs parallel to the flanged pulleys... lateral pressure from higher cable layers is transferred laterally at two line contacts to the cable winches
Implementation Method 2
variable-length traction element... providing additional tractive force to increase the lateral pressure stability of cable windings
Implementation Method 3
the layers are always wound in the opposite axial direction of the cable drum... In the parallel areas, the cable runs parallel to the flanged pulleys... lateral pressure from higher cable layers is transferred laterally at two line contacts
Data Source
AI summary
The disclosure relates to a crane, in particular a mobile lattice boom crane, having an upper carriage, a tiltable boom articulated to the upper carriage and a tiltable bracing frame articulated to the upper carriage. The bracing frame can be connected to the boom via a bracing and is connected to the upper carriage via an actively adjustable bracing cable, wherein the bracing cabling comprises a bracing cable mounted on a cable winch so that it can be wound up and unwound. According to the disclosure, the crane comprises a variable-length traction element, via which the bracing frame can be connected to the boom in an articulated manner and which is designed to exert a tractive force on the bracing frame in the direction of the boom. The disclosure also relates to a method for moving a crane according to the disclosure into a braced operating position.