Auxiliary Hoist Brake Assembly for Free-Spinning Drum Locking
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Solution Overview
Problem
Conventional hoist designs lack an auxiliary brake assembly, which can lead to a free-spinning cable drum, posing risks to aircraft, crew, and loads, especially when loads exceed the hoist's rating.
Innovation Solution
An auxiliary brake assembly is introduced, comprising a pinion, friction discs, a pressure plate, a gear nut, a screw, and a bearing, activated by an electric motor that detects free spinning and engages to lock the rotor gear and cable drum using a fastener system with a flange to compress the clutch assembly and lock mesh gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only a main brake assembly is used in conventional hoist designs, then the device complexity is reduced, but the reliability deteriorates due to the risk of free-spinning cable drum
Solution Approach 1:
The brake system is divided into two independent segments: a main brake assembly for normal operation and an auxiliary brake assembly for emergency/free-spinning conditions. Each brake assembly operates independently with its own actuation mechanism, allowing the system to maintain reliability through redundancy while managing complexity through functional separation.
Solution Approach 2:
The auxiliary brake assembly is pre-positioned and spring-loaded to engage automatically when the cable drum experiences free-spinning conditions. This beforehand preparation ensures that the emergency braking function is immediately available without requiring complex real-time control systems, thus improving reliability while limiting complexity growth.
2Object-affected harmful factors
If an auxiliary brake assembly is added to prevent free-spinning, then the safety is improved, but the device complexity increases
Solution Approach 1:
The auxiliary brake assembly is designed to self-actuate through a spring-loaded mechanism that automatically engages when the cable drum rotates in the free-spinning direction. The spring force and mechanical linkage create a self-regulating system that responds to harmful conditions without requiring external control signals, thereby improving safety while avoiding complex control systems.
Solution Approach 2:
A mechanical intermediary mechanism (spring-loaded actuator with cam or lever) is introduced to translate the free-spinning motion of the cable drum into activation of the auxiliary brake. This intermediary component simplifies the control architecture by providing direct mechanical coupling between the hazard condition and the braking response, reducing the need for complex sensors and control logic.
3Force
If the auxiliary brake assembly uses a fastener system with flange to compress clutch assembly, then the braking effectiveness is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The fastener system incorporates a spring-loaded mechanism that provides dynamic compression force to the clutch assembly. The spring allows for automatic adjustment of the compression force based on wear and operational conditions, maintaining effective braking force without requiring extremely tight manufacturing tolerances on the fastener and clutch assembly interfaces.
Solution Approach 2:
The spring constant and pre-load of the spring-loaded fastener system are designed to provide sufficient braking force across a range of operational conditions. By using a compliant element (spring) rather than a rigid fastener, the system can accommodate variations in manufacturing precision while maintaining the necessary compression force on the clutch assembly for effective braking.
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 preventing accidents due to overload conditions.
Implementation Method 1
a first plurality of friction discs coupled to a radially outer surface of the pinion, the first plurality of friction discs configured to lock the pinion
Implementation Method 2
a spring configured to compress the clutch assembly
Data Source
Figure 1~2
Figure 3
Figure 4
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.