Internal Auxiliary Brake for Tower Crane Stability
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Solution Overview
Problem
Tower cranes in disturbed wind conditions experience uncontrolled rotation due to torque imbalances, posing a risk of falling, especially when existing solutions require modifications to the crane or are not suitable for cranes with single geared motors.
Innovation Solution
Incorporating an internal auxiliary brake between the motor and reduction gearbox of the slewing gear motor, controlled by an electromagnet and spring means, which can be activated when the crane is out of service to prevent uncontrolled rotation without slowing it down during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional external brake is added to the geared motor output to prevent uncontrolled rotation in disturbed wind, then the crane stability is improved, but the device complexity and modification requirements increase
Solution Approach 1:
The auxiliary brake is nested within the geared motor assembly, specifically positioned between the motor output shaft and the reduction gearbox input. This internal placement allows the brake to be integrated into the existing motor structure without requiring external additions, thereby preventing uncontrolled rotation while avoiding increased device complexity and modification requirements.
Solution Approach 2:
The auxiliary brake function is merged with the existing geared motor assembly by incorporating it into the motor housing and utilizing the motor output shaft as the brake application point. This combination eliminates the need for separate external braking mechanisms and reduces overall system complexity while maintaining crane stability in disturbed wind conditions.
2Reliability
If a permanent braking torque is exerted to prevent uncontrolled rotation during weathervane setting, then the crane stability is improved, but the ease of operation deteriorates due to interference with normal rotation
Solution Approach 1:
The auxiliary brake is designed with dynamic control characteristics where the braking torque can be adjusted or deactivated based on operational requirements. During normal crane operation, the auxiliary brake can be deactivated or reduced to allow free rotation and weathervane setting, while during disturbed wind conditions, it activates to provide stabilizing braking torque, thus maintaining both ease of operation and crane stability.
Solution Approach 2:
The braking torque parameter of the auxiliary brake is made variable rather than fixed. The brake can be controlled to provide different torque levels depending on the operational state - minimal or zero torque during normal operation to allow easy rotation and weathervane setting, and increased torque during disturbed wind conditions to prevent uncontrolled rotation, thereby resolving the contradiction between stability and ease of operation.
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 allows for adjustable braking torque to stabilize the crane in disturbed wind conditions without modifying the crane, making it easily transposable between sites and applicable to both single and multi-gear motor systems, ensuring safe weathervaning without additional external brakes.
Implementation Method 1
controlled by an electromagnet and spring means, which can be activated when the crane is out of service to prevent uncontrolled rotation
Implementation Method 2
controlled by an electromagnet and spring means, which can be activated when the crane is out of service to prevent uncontrolled rotation
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The mechanism has an orientation geared motor (8) including an internal main brake (12) that is deactivated when a tower crane is deactivated. Additional braking units are activated when the tower crane is deactivated for exerting a brake torque on a turning part (2) of a tower crane to avoid an uncontrolled rotation of the turning part, during setting vane. The additional braking units are incorporated in the geared motor, where the braking units are in a form of an internal annex brake (15) i.e. single brake disc, intercalated between a motor (10) and a reducer (11).