Dual Brake Safety Device for Fall Arrest and Descent
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Solution Overview
Problem
Existing safety devices for fall protection, such as self-retracting lifelines and controlled descent devices, lack a unified mode for both fall arrest and controlled descent, which can complicate rescue operations and user safety.
Innovation Solution
A safety device with a rotatably connected drum, featuring a first and second brake assembly and a control mechanism that selectively engages these assemblies to switch between fall arrest and descending modes, utilizing a rotor with pawls and spur gears to manage cable payout and arrest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a self-retracting lifeline with a single brake assembly is used, then the device structure is simple, but it cannot provide both fall arrest and controlled descent modes
Solution Approach 1:
The brake system is segmented into two independent brake assemblies (first brake assembly with first pawl and second brake assembly with second pawl) that can operate independently or together. Each brake assembly can be selectively engaged through a control mechanism with first and second positions, enabling the device to provide both fall arrest mode (second brake assembly engaged) and controlled descent mode (first brake assembly engaged) functions.
Solution Approach 2:
The safety device is designed with multi-functionality by integrating both fall arrest and controlled descent capabilities into a single device. The drum, cable, housing, and control mechanism serve dual purposes: they can rapidly arrest falls through the second brake assembly or enable controlled descent through the first brake assembly, making the device universally applicable for both emergency stop and controlled rescue operations.
2Reliability
If a controlled descent device is used for rescue operations, then worker safety during descent is improved, but it cannot provide rapid fall arrest capability
Solution Approach 1:
The device dynamically switches between two operational states through a control mechanism with first and second positions. In the second position, the second brake assembly is engaged for rapid fall arrest with high reliability. In the first position, the first brake assembly is engaged for controlled descent during rescue operations. This dynamic reconfiguration allows the same device to provide both rapid stopping and controlled lowering capabilities.
Solution Approach 2:
The braking parameters are changed by switching between two brake assemblies with different friction characteristics. The second brake assembly provides high-friction rapid deceleration for fall arrest, while the first brake assembly provides lower-friction controlled deceleration for safe descent. The control mechanism enables changing the braking force parameter based on operational requirements.
3Adaptability or versatility
If dual brake assemblies are added to provide both fall arrest and descent modes, then operational versatility is improved, but device complexity increases
Solution Approach 1:
The control mechanism for switching between brake assemblies is merged into an integrated system where a single control element with two positions simultaneously manages both brake assemblies. The housing structure is merged to accommodate both brake assemblies, the drum, and the control mechanism in a compact arrangement, reducing overall system complexity despite the dual-function 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
Enables seamless transition between fall arrest and controlled descent modes, ensuring worker safety by effectively managing cable payout and arrest, thereby enhancing rescue operations and user safety.
Implementation Method 1
The first brake assembly includes a rotor to which at least one first pawl having a friction pad is pivotally operatively connected
Implementation Method 2
The drum is spring biased to pay out cable as tension pulling the cable is applied and to retract any of the cable that has been unwound from the drum as the tension on the cable is reduced or released
Implementation Method 3
The second brake assembly includes a gear assembly and at least one second pawl. The gear assembly includes a second spur gear. The second pawl is configured and arranged to engage the gear assembly when the drum rotates at a predetermined speed
Data Source
AI summary
A safety device with fall arrest and descending modes includes a housing, a drum, a lifeline, first and second brake assemblies, and a control. The drum is rotatably operatively connected to the housing. The lifeline has an intermediate portion interconnecting a first end and a second end. The first end is operatively connected to the drum. The first and second assemblies are operatively connected to the drum. The control is operatively connected to the first and second brake assemblies and has a first position and a second position. The first position selectively engages the first brake assembly in a descending mode and the second position selectively engages the second brake assembly in a fall arrest mode.