Hoist Auxiliary Brake Assembly for Cable Drum Free-Spin Locking
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Solution Overview
Problem
Conventional hoist designs lack an auxiliary brake assembly to prevent free spinning of the cable drum, which can pose risks to aircraft, crew, and load, especially when loads exceed the hoist's rating.
Innovation Solution
An auxiliary brake assembly comprising a pinion with a mesh gear, a clutch assembly, and a fastener with a flange that compresses the clutch assembly to lock the pinion, coupled with an electric motor that detects free spinning and activates the brake, ensuring the cable drum is locked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary brake assembly is added to prevent free spinning, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The auxiliary brake assembly is nested within the existing hoist structure, with the pinion gear integrating into the gear train and the clutch assembly incorporating friction discs and reaction plates in a compact stacked arrangement. This nesting approach allows the brake function to be added without proportionally increasing overall device complexity.
Solution Approach 2:
The pinion gear serves dual functions: it is part of the normal gear train for lifting operations and simultaneously acts as the braking element when engaged by the clutch assembly. This multi-functionality reduces the need for entirely separate components, thereby limiting the increase in device complexity.
2Strength
If a clutch assembly with friction discs is used to lock the pinion, then braking effectiveness is improved, but manufacturing complexity increases
Solution Approach 1:
The clutch assembly is segmented into discrete friction discs and reaction plates that can be manufactured separately and then assembled in a standardized stacked configuration. This segmentation allows each component to be optimized for manufacturing while maintaining overall braking effectiveness.
Solution Approach 2:
The braking effectiveness is controlled by adjusting parameters such as spring force, friction disc material properties, and disc thickness rather than by complex geometric designs. This approach simplifies manufacturing while maintaining the ability to achieve required braking performance.
3Speed
If a spring is used to compress the clutch assembly, then response speed is improved, but device complexity increases
Solution Approach 1:
The spring is pre-compressed during assembly to store potential energy, enabling immediate response when the fastener rotates to engage the clutch assembly. This preliminary action eliminates the need for complex actuation mechanisms while achieving rapid braking response.
Solution Approach 2:
The spring automatically compresses and releases to engage and disengage the clutch assembly based on the rotational position of the fastener, without requiring external control systems or additional actuators. This self-service mechanism reduces device complexity while maintaining fast response.
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 auxiliary brake assembly effectively prevents the cable drum from spinning freely, enhancing safety by providing an additional braking mechanism beyond the main brake, thereby reducing the risk of accidents and damage.
Implementation Method 1
a clutch assembly including a first plurality of friction discs coupled to a radially outer surface of the pinion, a second plurality of friction discs coupled to the hub, and a plurality of reaction plates interleaved between the first plurality of friction discs and the second plurality of friction discs
Data Source
Figure 1~2
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AI summary
An auxiliary brake assembly for use in a hoist, is disclosed. The auxiliary brake assembly comprises a pinion (410), a fastener (420), and a clutch assembly (450). The pinion may comprise a mesh gear disposed proximate a respective mesh gear (412) of a rotor gear. The clutch assembly may be disposed between the fastener and the mesh gear. The fastener may be configured to compress the clutch assembly in the event a cable drum (212) of the hoist is free spinning. The compression of the clutch may lock the pinion and the rotor gear and stop the cable drum from spinning freely.