String Trimmer to Outboard Motor Conversion Kit
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Solution Overview
Problem
Existing conversion methods for transforming string trimmers into outboard trolling motors face issues with attachment integrity and clutch burnout due to improper propeller sizing and insecure attachment, leading to reliability and durability concerns.
Innovation Solution
A conversion kit and method that includes a stainless steel annular sealed clutch bearing, adjustable motor mounting bracket, and a propeller with a centrally located hub and broached non-circular recess for secure attachment, along with vibration-damping components to enhance durability and prevent clutch burnout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a string trimmer is converted to an outboard trolling motor using conventional methods, then the cost is reduced, but the attachment integrity between propeller and drive shaft deteriorates
Solution Approach 1:
The drive shaft is divided into separate segments (upper shaft and lower shaft) that can be independently adjusted and secured. The propeller shaft is separated from the drive shaft through a universal joint assembly, allowing independent optimization of each component's attachment method to ensure integrity while maintaining cost-effectiveness.
Solution Approach 2:
The conversion kit includes pre-configured mounting brackets, universal joints, and shaft couplings that are prepared in advance with proper alignment features. The propeller shaft is pre-assembled with the gear box assembly, ensuring correct positioning and secure attachment before installation on the string trimmer, thereby preventing attachment failures.
2Ease of manufacture
If a string trimmer is converted to an outboard trolling motor using conventional methods, then the cost is reduced, but the clutch durability deteriorates due to burnout
Solution Approach 1:
The conversion kit modifies operational parameters by introducing a gear box assembly with appropriate gear ratios that reduce the load and speed transmitted to the string trimmer's clutch. This parameter adjustment allows the clutch to operate within its designed durability limits while still providing effective propeller drive, preventing burnout and extending service life.
Solution Approach 2:
The gear box assembly acts as an intermediary between the string trimmer's drive shaft and the propeller shaft. It provides mechanical advantage through gear reduction, distributing the load more evenly and reducing peak stresses on the clutch mechanism, thereby preventing overheating and burnout while maintaining cost-effective conversion.
3Reliability
If the propeller is securely attached to prevent breaking loose, then the attachment integrity is improved, but the device complexity increases
Solution Approach 1:
The conversion kit combines multiple attachment functions into integrated components. The universal joint assembly merges the shaft coupling, bearing support, and angular adjustment capabilities into a single compact unit. The propeller shaft connection integrates the gear box mounting and propeller attachment features, providing secure attachment without requiring separate complex mechanisms for each function.
Data Source
AI summary
An outboard trolling marine motor assembly, conversion kit and method for converting a string trimmer into an outboard motor assembly. The assembly and kit featuring a propeller, a clamp assembly, a spacer and a mounting bracket. The propeller having a plurality of blades radially extending from a centrally located hub featuring a substantially centered non-circular recess. The propeller and spacer suitable for being mounted to a non-cylindrical prop-shaft. The clamp having a U-bolt with spaced apart threaded ends, fasteners and a block with a semi-circular slot and a plurality of apertures for receiving the ends of the U-bolt. Slot and U-bolt forming a substantially annular interior region. The mounting bracket having a pivotable body and at least one adjustable clamp for securing the motor assembly to a portion of a watercraft.