Shift Drum Groove Orientation for Saddle Vehicle Durability
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Solution Overview
Problem
In manual shift transmissions for saddle type vehicles, radial loads on the shift drum during gear changes can cause displacement, leading to abrasion or torsion between the engagement groove and engaging pin, compromising durability.
Innovation Solution
The shift drum's engagement groove is oriented orthogonally to the greatest radial load direction, with a support hole for lubrication and a press-fitted engaging pin, ensuring no relative displacement and enhanced durability by restricting pin disengagement and facilitating smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the engagement groove is oriented parallel to the greatest radial load direction, then the engaging pin can easily engage with the shift drum, but relative displacement occurs between the engagement groove and pin causing abrasion and torsion
Solution Approach 1:
The engagement groove is deliberately oriented at an asymmetric angle (orthogonal) to the greatest radial load direction, creating a specific geometric relationship that prevents relative displacement between the engaging pin and groove during operation, thereby eliminating abrasion and torsion while maintaining engagement functionality
2Ease of manufacture
If the engaging pin is freely inserted through the sensor shaft, then assembly is simple, but the pin may disengage from the sensor shaft under radial loads
Solution Approach 1:
The engaging pin is preliminarily fixed to the sensor shaft through press-fit before assembly, establishing a secure connection in advance that prevents disengagement under radial loads during operation, while still allowing for straightforward assembly procedures
3Device complexity
If no lubrication is provided for the shift drum, then the structure is simpler, but the shift drum and engaging components suffer from increased wear under radial loads
Solution Approach 1:
A support hole is introduced as an intermediary structure that delivers lubricant to the shift drum bearing surface, reducing friction and wear between moving components under radial loads, while adding minimal structural complexity to the overall system
Data Source
AI summary
In a transmission for a saddle type vehicle wherein a shift position sensor for detecting the angular position of a shift drum has a sensor shaft disposed coaxially with the shift drum and wherein an engaging pin disposed along a plane orthogonal to the center axis of the sensor shaft and inserted and passed through and fixed to the sensor shaft is engaged with an engagement groove provided at one axial end of the shift drum, to restrain abrasion or torsion from occurring between the engagement groove and the engaging pin even if a radial load is exerted on the shift drum at the time of a shift change and thereby to promise enhanced durability. The longitudinal direction of the engagement groove is set in a direction orthogonal to the direction in which the greatest one of radial loads on the shift drum is exerted.