Zip Line Emergency Arrest Device Prusik Knot Tension Control
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Solution Overview
Problem
Existing zip line braking systems, including mechanical and manual methods, face challenges in efficiently controlling the speed and safe stopping of zip line trolleys, with current emergency braking systems like the Prusik knot struggling to maintain tension and control deceleration effectively, especially on horizontal zip lines.
Innovation Solution
An emergency arrest device that tensions and controls a Prusik knot by using a mirror-image frame with a tail fixation assembly and knot-body control assembly, including resiliently biased arms and a rotating hook member, to ensure controlled deceleration and arrest of the trolley upon impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Prusik knot is used as a backup braking system on a horizontal zip line, then the system provides emergency stopping capability, but the knot cannot maintain tension and control deceleration effectively
Solution Approach 1:
The patent introduces a housing as an intermediary device that contains and controls the Prusik knot. The housing includes a tail fixation assembly that maintains tension on the knot tail and a knot-body control assembly with resiliently biased arms that control the knot body's contact with the zip line. This intermediary structure enables the Prusik knot to function reliably as an emergency brake on horizontal lines by providing the necessary tension control and contact pressure that the knot alone cannot achieve.
2Reliability
If a mechanical brake system is installed at the end of a zip line, then the system can effectively slow and arrest the trolley, but the device complexity increases
Solution Approach 1:
The patent designs the emergency brake device to be self-activating through impact forces. When a trolley or primary brake impacts the device, the kinetic energy automatically tensions the Prusik knot and engages the braking action without requiring external control mechanisms, actuators, or complex control systems. The resiliently biased arms and tail fixation assembly work passively to maintain knot tension and control deceleration, eliminating the need for powered or electronically-controlled components.
3Device complexity
If riders use thick leather gloves to manually brake by grabbing the zip line, then the system requires minimal equipment modifications, but dislocated shoulders can result from this maneuver
Solution Approach 1:
The patent replaces the rider's hand as the braking intermediary with a mechanically-controlled Prusik knot system housed in a protective housing. The knot-body control assembly with resiliently biased arms provides controlled contact pressure on the zip line, distributing the braking force through the knot structure rather than concentrating it on the rider's shoulder through manual gripping. This intermediary mechanical system eliminates the direct human contact that causes injury while maintaining effective braking capability.
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 device effectively maintains tension on the Prusik knot to ensure controlled and safe stopping of zip line trolleys, providing a reliable backup braking system that can be used in conjunction with primary braking systems, enhancing safety and operational efficiency.
Implementation Method 1
A knot-body control assembly is mounted in the front of the device. The knot-body control assembly includes arms that are resiliently biased to push the body of the slide-and-grip knot rearwardly when the device is impacted.
Implementation Method 2
A Prusik knot is the most common of a class of so-called 'slide and grip knots' that use friction to stay in place on a larger line or rope.
Data Source
AI summary
An emergency arrest device for a zip line is disclosed. The emergency arrest device is designed to tension and control a slide-and-grip knot, such as a Prusik knot, that is tied on the zip line. The device includes a mirror-image set of sidewalls, a front endwall connected between the pair of sidewalls at a front end of the device, and a rear endwall connected at a rear end of the device. The front and rear endwalls have openings sized to permit passage of the zip line therethrough. A tail fixation assembly including a clamp is mounted in the rear of the device. A knot-body control assembly is mounted in the front of the device. The knot-body control assembly includes arms that are resiliently biased to push the body of the slide-and-grip knot rearwardly when the device is impacted.