Hand Winch Friction Brake Torque Threshold
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Solution Overview
Problem
Prior art hand winches with automatic friction brakes pose safety risks due to rapid shaft rotation during unwinding and are unclear in operation, especially for inexperienced users, requiring specific directional pulling to deactivate the brake.
Innovation Solution
A hand winch design featuring a friction means between the shaft and gear member that establishes a torque threshold, preventing slippage and activating the brake only when external resistance exceeds this threshold, ensuring the brake is not activated during unwinding and can be easily reactivated by slight contact, thus enhancing safety and ergonomics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the friction brake is deactivated by moving the brake disk to the off-set position, then quick unwinding of the elongated member is enabled, but rapid rotation of the shaft may cause injury to the operator or bystanders
Solution Approach 1:
A friction device is introduced as an intermediary between the shaft and the housing. This friction device includes a friction element that can be pressed against the shaft to create frictional resistance, thereby controlling the shaft's rotation speed during quick unwinding operations without requiring the brake to be engaged
Solution Approach 2:
The friction device allows dynamic adjustment of the frictional resistance parameter between the shaft and housing. By varying the pressing force on the friction element, the system can transition between different operational states: free rotation for quick unwinding, controlled rotation for safe operation, and locked state for holding loads
2Extent of automation
If the automatic friction brake is controlled by the position of the pivot member, then the brake can be activated or deactivated, but it is unclear for inexperienced operators when the brake is activated and requires specific directional pulling
Solution Approach 1:
The friction device is designed to be automatically activated by the operator's natural actions. When the operator pulls the elongated member in the unwinding direction, the friction element is automatically pressed against the shaft through the mechanical connection, providing frictional resistance without requiring the operator to understand complex brake control mechanisms or pull in specific directions
3Ease of operation
If the gear member is rotatably mounted on the shaft with frictional contact, then the brake can be activated by overcoming initial resistance, but the brake may be accidentally activated during normal unwinding operations
Solution Approach 1:
The friction device creates a localized friction zone between the friction element and the shaft, distinct from the gear member's engagement with the shaft. The friction element is positioned and dimensioned such that it only contacts the shaft when sufficient force is applied in the unwinding direction, creating a threshold effect that prevents accidental activation during normal operations while allowing deliberate activation when needed
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 design allows secure loading and quick unwinding of flexible members while preventing accidental brake activation, reducing operator risk and simplifying operation by ensuring the brake is only engaged when necessary, thus enhancing user safety and usability.
Implementation Method 1
the gear member moves axially from the release position to the brake position, generating braking forces opposite the direction of unwinding the elongated member
Implementation Method 2
a friction means between the shaft and gear member that establishes a torque threshold, preventing slippage and activating the brake only when external resistance exceeds this threshold
Data Source
AI summary
A hand winch including a winding roll, a flexible elongated member, a shaft connected to the winding roll, a friction brake including a brake disk and a gear element engaging the winding roll and mounted on the shaft. The gear element has a release position and a brake position in which the gear element enters into frictional contact with the brake disk, generating a braking torque resisting winding off the flexible elongated member. Friction means is provided between the shaft and the gear element for generating a frictional resistance therebetween such that, if a driving force acting on the gear element does not overcome the frictional resistance established by the friction means, the gear element drives the shaft through friction means. However, if the driving force between the shaft and the gear element overcomes the frictional resistance, relative movement between the gear element and the shaft occurs.