Drop Down System

[John H.]

Using a drop down system, we have experienced some problems. Someone on our team proposed asking questions on this forum, so, here I go.

Bear in mind that our robot does not meet the size restrictions. We have implemented a drop down system to fully use our robot.

1) We use two pistons to fall down. One seems to be falling at a different speed than the other. Our robot falls down on one corner, lifts its back high into the air and then drops fully. Consequently, our frame is being bent. How should we solve this problem and drop down smoothly?

2) Our two pistons are connected to a reverse L-shaped bracket/metal piece. This metal piece goes to the end of the size limit. Is there any suggestions for keeping this piece together and weight reducing?

3) Any suggestions for a suspension / any other suggestions?

Thanks a lot for your help.

[grego]

pneumatics is just like electricity in that your air (the current) will pass at the point of least resistance. as for solving this problem, i dont know what to tell you. getting 2 pistons to acuate at the same speed is one of the oldest (and toughest) problems in fluid power. all i can say is try and do it w/ one or use a motor instead of pistons. either way theres no quick fix i know of.sorry

[John H.]

A motor is heavier than two pistons. Also, its a little late to change designs.

[Joe Ross]

Are you using flow controls on the pistons, and are they set exactly the same?

[f22flyboy]

make sure the little knobs (flow controls) at each end of the pistons are exactly equal

[John H.]

We have a "splitter" connected to both pistons with the flow control knobs located on the "splitter". This way the pistons' control knobs would be set equally.


P - Splitter - P
I ............ I
S ............ S
T ............ T
O ............. O
N - Splitter - N

(Sorry for the crude drawing.)

[John H.]

Another question - Is it legal to work without a compressor?

[Joe Ross]

Yes it is legal to work without the compressor. Just make sure to remember to charge the tanks before each match

Do the pistons still drop down at different weights when they aren't pushing anything? Try lifting your robot off the ground.

[SuperJake]

Haven't checked up on the Pneumatic Rules recently, but you could possibly run both pistons off one solenoid valve and make sure the tubing leading to both pistons is the same length. That'd be my quick fix.

[Greg Needel]

another thing you might want to look at is your weight distribution.....i know that if the cylnders are too small or are just the right size it is possible that you have more weight on one then the other and you are actully pusing the air out of the cylnder with gravity...

I think that I can help you more about your frame bending but I would need to see a picture because that really just means that you arn't distributing your weight enough . rembmer newton for every action there is an equal and opposite reation. what ever force your cylnder is pushing against the floor it is pushing on whatever beam it is attached to...hope this helps

[Josh Hambright]

try adding flow restrictors like stated above. Just keep tweaking em till they both extend at the same rate.

[Lloyd Burns]

The advice about same length tubing given above is quite sound.
We had a fair size cylinder operating a moveable punch on a large press, with slightly different sizes of tubing, and before it would operate properly the tubing had to be just so.

However, you might want to consider different rates on both cylinders. Just remember to use flow restrictors on only one end of each cylinder - one end's restrictor interferes with the operation of the other.

It was nice to read in the First forums, that First finally admitted you didn't need two/cylinder, mounted on the cylinder as stated in the pneumatics manual, and ignored so successfully.

[Josh Hambright]

erm...
why didn't anyone tell me this...

*packs some regular elbow connectors for cleveland*
DOH!