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Hello all, 

I am trying to design a telescopic elevating platform based on a rack and pinion configuration. The design is based on this video from youtube (click the link here). The video shoes this in a horizontal configuration. I want to use this mechanism to build a vertical lift. For that I need to perform some calculations. The telescoping effect achieved by this mechanism is of practical use in compact applications. Can anyone please help me out with the calculations needed to size the motors and the size if the rack and pinon for this? Please see the diagrams attached to get a better idea of the problem. I am particularly stuck with the effects of friction in this system.

lift.png

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Friction will be a major problem, and it all depends upon how you guide the moving member. What do you plan to use as a guide? There is simple sliding contact, various ball or roller guides, etc. A lot depends upon your budget, but the better the guide quality, the easier your system will work.

DrD

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52 minutes ago, DrD said:

Friction will be a major problem, and it all depends upon how you guide the moving member. What do you plan to use as a guide? There is simple sliding contact, various ball or roller guides, etc. A lot depends upon your budget, but the better the guide quality, the easier your system will work.

DrD

Thank you for the reply.

If I was to simplify my question, I would ask how to calculate the friction losses that occur in a rack and pinion for a vertical lifting operation. The assembly slides relative to each other on the bearings shown. However, I am concerned about calculating how much frictional losses will we get due to the interaction of the rack and pinion when the 100kg load is hung on the cantilever rod. 

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Sounds like you are narrowing your question to friction losses in the rack and pinion only, exclusive of the guide mechanism. This depends upon the details of the tooth design (arc of approach/arc of recess) and upon the lubrication. If done well, these will probably be small relative to the friction in the guides.

DrD

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