four bar vrs Linear lifts

What are the pros and cons of both?

I need to lift a 21" ball 36" of the floor in no more than 15 seconds.

fourbar. No question about it. jack that think up with rubber bands and you’ll be able to lift anything short of a bowling ball in 15 seconds.

I believe you meant to say “anything including a bowling ball”

I’d agree. If you are looking at lifting something in 15 seconds, then the four bar is the way to go. Generally, a four bar is faster than a linear lift. However, I’d like to point out the fact that a four bar would not be good for lifting weights to a high distance. A linear lift with a worm gear could easily achieve that without breaking. As the required height becomes higher, the length of the arm would be longer. This would be bad because you would have less fulcrum with your arm. Add more weight to your arm and your motors could break. Several of my fellow teams, had the same problem when they tried to lift heavy stars, for their arm kept backtracking.

Four bar all the way. Our team’s can lift upwards of 8 pounds in under 2 seconds with only about 20 rubber bands.

20 rubber bands? How were you able to pull it down?

8 motors :smiley:
Honestly though, I’m not too sure. But hey, I’m not going to argue. There are 8 speed motors at a 1:5 ratio. Without the rubber bands, the bot can lift itself no problem. With the rubber bands, the bot can only lift itself about 2/3 of the way. Even without the rubber bands we are more than capable of lifting all 4 cubes and a few stars. I guess it’s just raw torque.

Wow. That’s amazing that you can do that. We have 6 speed motors with a 1:11 ratio and we don’t have the capability to do that. But lifting all 4 cubes? That is 6 and 1/2 pounds that you can lift without rubber bands.

When we get the actual hanging hook on, perhaps I’ll post a teaser video.

I meant a four bar reverse. If that changes any thing.

I assume you are referring to the FTC game… Are you building your robot using vex parts?

Yes, I am referring to the FTC game. No we are not using VEX EDR parts, we are using some VEX Pro parts.

Chief Delphi and FTC forums may be of better help then, all of the above answers involve vex parts…