[Gearbox] How to design a shift drum?

Sujet: [Gearbox] How to design a shift drum? Lun 5 Oct 2015 - 7:46

Hello everyone, I'm looking for some information about shift drum calculus and design.
Could you give me some information?
Thanks
[Gearbox] How to design a shift drum? 771973

[Gearbox] How to design a shift drum? 771973

Sujet: Re: [Gearbox] How to design a shift drum? Lun 5 Oct 2015 - 8:16

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This website give intresting information about how works a gearbox
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For the shift drum,
you have to calculate the lateral diplacement you need for the gear to match and emboss it on the drum.
You'll need to design finely all the clearance between each parts.

You are playing with the hard parts af the mecanichal design, with high probability to encounter some problem on your first try ....

Good luck !

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Sujet: Re: [Gearbox] How to design a shift drum? Mar 6 Oct 2015 - 5:45

Hello,

shift drums using a rotating angle of 60 degrees between every selected gear and for example a six speed shift drum uses a rotation of five times 60deg (300 deg) to shift from first to sixth gear. So the neutral position between first and second has a 30deg rotation, right in the middle.

The grooves, where the selector forks slide through are designed to provide a smooth moving and acceleration of the selector forks on their own shaft. The grooves are radiused on both of the flanks (inner and outer flank), with that you can avoid a locking position by hiting the ramp of the groove. During the rotation of the drum (60 deg) there will be a stroke who moves the selector forks.

At the beginning and at the end of the rotation of the drum (between two gears) there will be a rotation angle where is no stroke. That is needed to compensate tolerances during rotation and to provide a correct selector axial position.

If you need help with the design, feel free to send me your 3D model.

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Sujet: Re: [Gearbox] How to design a shift drum? Mar 6 Oct 2015 - 16:35

Hello,
we do the design of some shift drum at work, but for machine tools.(not realy shift drums but transmission drums)
If your question is "you to use SOLIDWORKS in order to design shift-drum?" i can pick to informations.
See you tomorrow

Sujet: Re: [Gearbox] How to design a shift drum? Mar 6 Oct 2015 - 17:20

I think the best way to design such part is to copy a good drum and complete kinematic of a very good gear box with similar design. Honda gear boxes are generally good.
Dan

Sujet: Re: [Gearbox] How to design a shift drum? Mar 6 Oct 2015 - 21:06

new production for kreidler [ made in Holland ]

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Sujet: Re: [Gearbox] How to design a shift drum? Mer 7 Oct 2015 - 10:38

Thanks to all for your answers!!
marcolemotard yes, I am Solidworks user.

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