Propeller Shaft Line Cutter with Beveled Disk
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Solution Overview
Problem
Existing propeller drives for watercraft, particularly in work boats and vessels like trash skimmers, face issues with fish line and debris winding around the shaft, causing damage to the rubber seal and potential leakage due to the inefficacy of existing debris removal solutions like spools and exposed cutters.
Innovation Solution
A line cutter is integrated into the propeller drive housing with a beveled, stainless steel disk having a circular opening that provides a small clearance to grind or tear debris, such as fish line, and is securely fastened to prevent corrosion, eliminating exposed edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a spool and exposed cutter are used to remove debris, then debris removal capability is improved, but reliability deteriorates and safety deteriorates due to exposed sharp edges
Solution Approach 1:
The patent introduces an intermediary mechanism - a rotating cutter wheel with cutting edges that engages with debris on the spool. This intermediary transfers the cutting action from an exposed fixed blade to a controlled rotating element, improving reliability while maintaining debris removal capability. The cutter wheel is driven by the spool's rotation, creating a self-actuating system that reliably engages debris without requiring exposed sharp edges.
2Productivity
If a spool and exposed cutter are used to remove debris, then debris removal capability is improved, but safety deteriorates due to exposed sharp edges
Solution Approach 1:
The patent moves the cutting action from a two-dimensional exposed blade surface to a three-dimensional rotating wheel structure. The cutting edges are positioned on the periphery of the rotating cutter wheel, which is driven by spool rotation. This dimensional change allows the cutting action to occur within the mechanical assembly rather than exposing sharp edges to the external environment, maintaining debris removal while eliminating safety hazards.
3Reliability
If a small clearance line cutter is used, then reliability is improved by preventing debris winding, but device complexity increases
Solution Approach 1:
The patent merges the line cutter function with the existing spool mechanism. The cutter wheel is driven by the spool's rotation, combining the debris accumulation function of the spool with the debris cutting function of the wheel. This integration eliminates the need for separate actuators or complex control systems, reducing device complexity while maintaining reliable seal protection through consistent cutting action.
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 solution effectively prevents debris from winding around the propeller shaft, protecting the seal and reducing the risk of leakage while being unobtrusive and safe, as it uses a beveled edge to cut through debris without exposing sharp edges.
Implementation Method 1
the small clearance at the line cutter grinds or tears the line
Data Source
AI summary
A line cutter in the form of an apertured disk or plate mounts onto the housing of a propeller drive or screw drive. The line cutter mounts over the propeller shaft, and covers the propeller shaft seal. The line cutter opening has a small clearance over the shaft which is smaller than a standard fish line gauge, i.e., about 0.002 inches. Fishline or other debris encountered by the screw drive winds around the shaft and winds back until it is torn, ground, or cut when it encounters the circular cutting edge at the small clearance. This line cutter is useful on a trash skimmer work boat.