Two-Piece Motorcycle Steering Stem Assembly
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Solution Overview
Problem
The existing steering assembly of a motorcycle faces challenges in achieving a high steering joint clamp load without compromising ideal steer damping and handling performance due to the radial clearance required for assembly, which limits the ability to prevent slip between the steering stem and the bearings.
Innovation Solution
A two-piece steering stem assembly is introduced, where a first stem member is inserted from one end and a second stem member from the opposite end, both being fixedly secured at a joint within the steering head, eliminating radial clearance and ensuring zero-slip interfaces with tapered roller bearings for improved stability and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-piece steering stem is used with radial clearance for assembly, then the steering assembly can be easily assembled, but slip occurs between the stem and bearing inner races, compromising steer damping and handling performance
Solution Approach 1:
The steering stem is divided into two separate stem members that can be independently inserted into the steering head from opposite sides. This segmentation allows each stem member to be assembled with its respective bearing without requiring radial clearance, as each member is secured from one direction only. The two stem members are then joined together to form the complete steering stem assembly, eliminating the slip issue while maintaining assembly ease.
2Reliability
If high clamp load is applied to limit slip between stem and bearing, then slip is reduced, but ideal steer damping and handling performance are compromised
Solution Approach 1:
By segmenting the steering stem into two members assembled from opposite sides, the patent eliminates the need for high clamp loads. Each stem member is secured with minimal loading from its respective side, preventing slip without applying excessive force that would compromise steer damping. The segmented design distributes the securing function across two locations rather than concentrating it at one high-load interface.
3Device complexity
If a single-piece steering stem is used, then the structure is simple, but radial clearance must be provided which limits clamp load and allows slip
Solution Approach 1:
The patent divides the steering stem into two separate members, each inserted from opposite sides of the steering head. This segmentation eliminates the need for radial clearance in the traditional single-piece design, as each member is secured from one direction only. The two members are then joined together with a joint, creating a more complex but stable structure that prevents slip while maintaining reasonable assembly simplicity.
Data Source
AI summary
A steering stem assembly for rotatably coupling a steering assembly to a steering head of a motorcycle main frame. The steering stem assembly includes a first stem member configured to support a first end of the steering assembly on a first end of the steering head and a second stem member configured to support a second end of the steering assembly on a second end of the steering head. The second stem member is formed separately from the first stem member. A joint is defined between the first and second stem members and fixedly secures the first stem member with the second stem member.