Lock Ring Mounting Assembly for Marine Stern Drive Engine
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Solution Overview
Problem
Prior marine stern drive engine mounting assemblies experience loosening of height adjustment nuts, leading to engine misalignment and coupler failure due to inadequate retention of adjustment nuts, often caused by improper bending or placement of tab washers, which are difficult to access and secure.
Innovation Solution
A mounting assembly featuring a lock ring with downwardly extending arms that engage and secure adjustment nuts, preventing rotation, combined with a self-locking nut and a mounting base with flanges for secure attachment to the watercraft, ensuring constant engine position and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tab washer is used to retain the adjustment nut, then the nut should be prevented from moving, but the tab washer is difficult to access and properly secure, leading to loosening
Solution Approach 1:
The patent introduces a lock ring as an intermediary component between the adjustment nut and the mounting bracket. The lock ring features a tab that engages with a slot in the adjustment nut and another tab that engages with a slot in the mounting bracket, effectively mediating the retention function and eliminating the need for difficult-to-access tab washers.
Solution Approach 2:
The lock ring moves the retention mechanism from a two-dimensional planar engagement (tab washer against nut surface) to a three-dimensional multi-point engagement system where the lock ring's tabs engage with slots in both the nut and bracket, providing retention in multiple directions and planes.
2Reliability
If the tab washer is bent tight against the nut, then the nut should be secured, but the location is difficult to see and access, causing installers to fail or forget to bend it properly
Solution Approach 1:
The lock ring incorporates visual indicators including a colored portion that changes color or becomes visible when properly installed, and a visible tab that extends into a slot. These visual cues make it immediately apparent whether the lock ring is correctly positioned and engaged, eliminating the difficulty of verifying tab washer installation.
Solution Approach 2:
The visible tab of the lock ring acts as an intermediary indicator, providing a clear visual signal of proper installation without requiring the installer to look into difficult-to-see locations. The tab's position and engagement with the slot are easily observable from outside the mounting bracket.
3Reliability
If the tab washer bends over a corner of the nut rather than on a wrench flat, then the nut will not be retained properly, but proper bending is difficult to achieve
Solution Approach 1:
The lock ring's tab is designed to engage with a slot in the adjustment nut, providing a guided engagement path. This intermediary mechanism ensures that the retention force is applied precisely where needed (on the wrench flat or designated engagement surface) rather than relying on imprecise tab washer bending by the installer.
Solution Approach 2:
The lock ring structure is self-aligning and self-securing. As the lock ring is installed and tightened, its tab automatically engages with the slot in the adjustment nut at the correct position, eliminating the need for the installer to manually bend the tab washer with precision. The design performs the retention function automatically through its structural geometry.
4Reliability
If the adjustment nut is not properly retained, then the engine alignment is lost and coupler fails, but adding more complex retention mechanisms increases device complexity
Solution Approach 1:
The lock ring combines multiple functions into a single component: it retains the adjustment nut, provides visual indicators of proper installation, and structurally integrates with both the mounting bracket and adjustment nut. This merging of functions reduces the need for separate tab washers, instructions, and verification steps, thereby reducing overall system complexity despite enhanced reliability.
Data Source
AI summary
A mounting assembly for a stern drive engine including a mounting base, an engine mounting foot or bracket for securing an engine to a watercraft, and a lock ring for securing the engine mounting bracket in a constant position relative to the mounting base. The mounting base includes a threaded mounting bolt to receive a first adjustment nut, the engine mounting bracket, the lock ring and a second nut. The bottom surface of the locking ring engages a top surface of the engine mounting bracket with a downwardly extending arm or arms of the lock ring extending through an aperture in the engine mounting bracket to engage the first adjustment nut. The threaded bolt of the mounting base extends through apertures of the engine mounting bracket platform and mounting ring, and a second nut engages the top surface of the lock ring, preventing rotation of the first adjustment nut, and ultimately limiting movement of the marine stern drive engine.