Does anyone have any pictures of their chain lift from last year? I know 720p had one in the World Cup. If you could post the pictures, that would be so awesome! I am trying to figure out how to build one.
I have read over this article: http://www.aura.org.nz/archives/991 and I get how to build the main structure, but I cannot figure out how to attach a hopper or ramp like the ones used for Gateway. Any help would be appreciated.
The sprocket at the top is bolted onto you’re chassis, the main structure holding up your lift. The sprocket at the bottom is bolted onto your hopper, whatever bucket or ramp that is lifting up. The motion of the lift is achieved by driving a gear (60 tooth in the article) bolted onto the actual bar. However, I’ve never used those threaded beams to twist the chain like that in the picture.
Unfortunately i do not have a picture of it on a robot, but i would use atleast 4 lock bars. With this, you can easily adjust the angle of of your intake. However, since it is metal and plastic, i would layer these up
From browsing though the picture on AURA’s Flickr, I think this one explains the best what I think you are asking:
The wide c channel on the left would be your intake ramp/basket/hopper, and you would mount another sprocket in a similar way on your chassis/base of the lift.
You want it so that one sprocket is bolted into the chassis/base of the lift, and the other sprocket bolted into your intake basket (or other intake storing mechanism). You then have the “arm” of your lift attached so it can spin freely around the sprockets. This arm is then powered the normal way you would power an arm on a 4 bar, 6 bar etc.
Note: make sure that the axle that is going through the gear on your arm is not also going through the sprocket on your chassis/base of the lift.
I hope this has helped! Let me know if you want a clearer explanation.
Your sprocket on the tower is bolted to the robot, and does not move rotate about it’s axis. The sprocket on the bottom is bolted to the ramp, and rotates relative to the arms on your lift. It does not rotate relative to the ramp, and moves in a circle around the top sprocket.
Check out these pictures of one of our chain lift robots from last year.
Extra for experts: You can make the ramp get steeper / shallower as the arm lifts by changing the the ratios of the two sprockets, if you are looking for that sort of thing.
A very bad thing. It cost them a few matches at a tournament. What happened was, they had a scissor lift using the rotational actuation (a big gear in the middle of the “X” to turn one of the bars), but they didn’t screw the gear to the bar of their lift. Instead, the gear turned a shaft that was fastened to the bar by a shaft locking bar. After a little while of usage, the shaft could no longer take the strain, and it twisted up into something that resembled a twizzler.
that seems really strange system… I see the advantage of powering a scissor lift in the middle, but wouldn’t it be more reliable to use a cam system with chain? Cause drive shafts are less than half an inch thick.
But for the teams who did do that, wouldn’t spacers divided by washers prevent or at least resist twisting. If the scissor lift slams on it self, maybe some foam/non slip pad would be useful to slow down the impact, spreading out the force over time.
what i was thinking for this scenerio was that the hopper is attached to the lockbar to achieve the desired angle, then the lock bar is attached to the metal, then the metal is attached to the sprocket to achieve the necessary rotations.
ohhhhhhhhh. yeah, that should be called a chain arm, or at least a rotating chain lift or something. Chain lift seems to refer more to a linear movement using chain. This is angular movement, therefore rotating chain lift or angular chain lift would be better.
Calling it a chain 4 bar is incorrect because it has the bonus 4 or 5 holes that the 6 bar has that is why 404 called it a virtual 6 bar. It has always been my policy to call it a chain bar because it shares the main benefits of the 4 bar 6 bar 8 bar but it uses chain to get the affect while a 4 bar uses 4 pieces of metal but virtual 6 bar is just as accurate just can easily confuse people.
For people new to the chain bar think of it like a 6 bar that can spin in a full 360 degrees.