Gear Ussage

I am wondering what the robotics world (you) have to say about this. What are the best places to put gears? Our plan right now is to make a square chassis mount mechanum wheels on the out side and make a scissor lift arm. Where do you suggest that we put gears? Any advice? Plans you would be willing to share?

Thank you for your help. It is much appreciated.

What do you mean by “Where do we put gears?”

Are you asking if you should use gears for either you lift or your base?
If so, Yes for the lift & No for the base.

Or are you asking where you should fit the gears for your scissor lift into the design?

Or are you asking how/where you should power your scissor lift?

First of all, it is very hard to give advice when your description is so vague, however that could just be me. It’s been a long day. lol

What I would reccommend is you calculate where the stress and load will be best evened out and you’ll get the most leverage. Just adjust/add to your design to work with that.

Edit: Just wanted to add - I disagree with Highwayman about gears on the base. If designed well, it is possible to have very low friction gear setups on your base. I have to just say also that I never EVER reccommend using mechanum wheels. Just my two cents.

I would not recommend mounting wheels on the outside of a base. You want all axles to be supported on both sides of the wheel to reduce friction and bending.

Not to mention that with mecanum wheels there will be forces along the axle. Here is one way to use gears.

jpearman’s latest drive

Here’s another.

compound gearing

I tend to use gears when I am trying to slow the thing that I am diving’s speed down. when I am speeding it up, I tend to use HS chain. I prefer a direct-driven drive base so I rarely use gears or chain in those places. I just about never use the low strength gears over the high strength ones.

I have no experience with scissors because I have avoided them; but if I were to build one, I would make sure that it is powered in such a way that the speed that the lift goes up remains constant as it goes up and down. many of the most straight forward ways to power a scissor result in it lifting up very fast at the bottom of it’s travel and very slowly at the top. This was fine last year but it only gets amplified when you add more stages to it. The best way I can think of to make this happen would be to lift the first stage with a vertical elevator (not the horizontal one that the scissor slides on because that will have the same problem) and maybe power it with rack and pinion gears.

Here is an example of the general Idea of what I am talking about being used to power an arm I am working on.
https://vexforum.com/attachment.php?attachmentid=8556&stc=1&d=1409252944
IMG_8945.jpg