6 Speed Motorcycle Transmission

Challenge

A large motorcycle manufacturer approached JTEKT with the need to design a 6 speed transmission for a new model.

The existing design was old and was inherited through a merger. The decision was made early on to develop a completely new design.

In addition, the customer had already progressed far in the new design so "bearing space" was already set.

Customer provided a duty cycle and gear details for JTEKT to develop the bearing loads and develop a model in JTEKT's bearing analysis and modeling program called SSAP.

Other considerations:

-?????????Bearing mass and size needs to be minimized

-?????????Housings are aluminum

-?????????There are shock loads present that must be considered for selecting a static load rating

Detailed bearing analysis showed that two bearing positions did not give the desired life. As stated above the customer design had progressed to a point that changes to bearing size would delay the program and place the program launch in jeopardy.

Solution

JTEKT utilized bearings with larger rolling elements and a special life enhancing heat treatment. This combination of features is designated as a RSH2 bearing. The life enhanced bearing allowed an increase in bearing life and saved the customer cost impact from a redesign and saved their launch.

JTEKT’s ability to use SSAP to analyze complex transmissions was key to providing the customer confidence in the bearing selection. The transmission is in successful service and the initial sizing, fitting and clearance required no revisions.