# Help with a lift

So at the beginning of the year we decided to try new designs we never had before and move away from the generic six-bar and so on. So one way we accomplished this was by creating an elevator style lift. Now the help that we are in need of doesn’t come in actually fixing the lift, we have had no issues with the lift accomplishing what we intended it to. We just have realized recently that we are not efficent enough to compete at the level that we need, so we did some research and calculated ratios and such using threads such as this one:

https://vexforum.com/t/team-1103-robot/18347/1&page=19

And recently we tried to speed up our ratio by trying larger drive sprockets, to speed up the lift which in turn would lower the torque, and to counteract this a gear ratio for torque so we still have speed and power. As of now we have a 1:1 from two 393’s on each tower (our original ratio setup, so we’re back to square one :p), and we have tried multiple gear ratios and sprockets as follows:

3:5 for torque with a:
.25" dia
.5" dia
.75" dia
1" dia
Drive sprocket,
as well as a 1:2 for torque ratio with the same trails of drive sprockets.

So the main point of this post is to see if anyone has any suggestions on what we could do to speed up our lift while still also having the torque/force required to hang. If you need any more info let me know and I can get some to you! Thanks a lot!

From what I know I don’t think you can increase both torque and speed and the same time without adding more power (ie another motor, reducing the weight of the lift). If you can’t add another motor then I would suggest choosing one over the other (either build for torque which will allow you to hang, or build for speed which might not let you hang but will let you score fast).

From my experience so far, what Farce said is exactly correct. There is no way to speed up a lift without sacrificing torque with the same input of power. I would guess an elevator lift would be especially difficult for this. That is why people generally use six bars and such. From my experience, they provide a good amount of torque and can be quite fast as well. I have been really interested in elevators though. Can you tell me a little about how you made yours?

I guess I should rephrase my question
What I’m trying to say is do you guys, or anybody have and idea of a better gear ratio, something that is more efficient. I know that you have to sacrifice speed for torque or vice versa and we just want to find a ratio that is more speed and less torque but still allows us to hang. And we weren’t sure how to go about finding one or calculating one.

This year my team also had an elevator and what we did to accomplish both speed and torque was to create a two speed transmission. This allowed us to have a 1:3 gear ratio for speed and a 3:1 for torque. It worked great we made it to semifinals in our first competition, but it takes a lot of time to calibrate.

That’s a really good idea, I’ve never thought of doing that

Wow that’s quite interesting. Did you use pneumatics or a motor to switch gears? And could you possibly send me some images of your elevator lift? I’m trying to get one built for one of our robots and it’s proving to be a more difficult task than I expected.

I used a double acting pneumatic to switch the gears, and I am sorry I do not have any picks at the moment another team member has them, but what are you having trouble with?

Just to add a little more information you will have to bevel all of the gears to allow the transmission to slip when you switch gears other wise you will have a lot of broken gears.

At this point, I’m just trying to make one that works well and can lift my robot. I’ve never built one and I haven’t found a ton of designs.

2 Motor 1:7 works for low hang (at least it has for us). A lot of teams are using 4 motors on a 1:7 for high hanging. You can also use pneumatics for hanging assists.

Hey Jesse. Regarding this though, is that for a six bar or for an elevator? I’m debating between a four motor six bar or a two motor elevator and a two motor six bar. It just depends on if I can pull my robot up with a two motor elevator though. Could I do a pretty high torque ratio? I wouldn’t be using the elevator for much that I would need to do quickly.