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Unread 28-01-2007, 13:10
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Re: Risk of the Lift?

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Originally Posted by RaMoore View Post
Could you be more specific with what teams can expect then for lifting? 1/2 of 188lbs? 1/4 of 188 lbs?

Just some ball park estimate because I think alot of teams did the math and came up with 188lbs and rejoiced (we did). If this isn't what they should expect then I think i'ts important you get information out there.
Our experiments showed that a typical cylinder under load could only "Move" between 80 to 85% of it theoretical maximum force. This is probably due to frictional forces in the cylinder and the rest of the mechanisms it was driving. There is also the affect of the transmission of pneumatic energy through the small hoses and valves.

This is no different than motor driven systems. Think of how the efficiency of a gear box reduces the actual transmitted power in those systems. We have learned to not expect 100% of the motor's torque to drive the final system. Another way to think of it is that we do not expect a motor to drive a system at its stall torque - it can hold that much torque - thus the term stall. It cannot drive at that torque. The analogy is that a pneumatic cylinder "stalls" at the rated max force. But it cannot move anything with that much force. And of course the inefficiencies reduce what force it can move.
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Unread 28-01-2007, 13:22
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Re: Risk of the Lift?

I thought there was something fishy about my math. I didn't care that much cause my team HAS used this cylinder in the past to lift our bot (one just one, not two or three but one, and it was even in the pulling orientation). It can lift a 130-pound bot.

The problem we had was that it used our entire air storage to retract the cylinder half way and then there was a wonderful time period when the robot would inch up as the compressor slowly lifted the robot off the floor. I would strongly suggest teams don't use this option unless it is the only pneumatics they use. These cylinders just use too much air. Our team is going to use motors to raise our lift and pneumatics is going to be used in very small operations (like latches and so on...)
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Unread 28-01-2007, 13:58
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Re: Risk of the Lift?

I think the best thing to do would be to test your ramp with last years robot, or with a human being on a cart (some kind of a test object)
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Unread 28-01-2007, 17:27
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Re: Risk of the Lift?

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Originally Posted by Mib View Post
I think the best thing to do would be to test your ramp with last years robot, or with a human being on a cart (some kind of a test object)
Amen pull last years bot out of moth balls set it up just like you are planning on having the other robots doing it and give it a try. Worst case scenario you drop a robot you probably won't ever use.
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Unread 01-02-2007, 08:52
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Re: Risk of the Lift?

Personally, I think people should go with what they want. If you play it safe all the time, you'll never get anywhere. You have to take risks once in a while, even if it's a good outcome or a bad outcome. just be prepared for anything and everything. If you worry about everything too much, that could hold you back. So just take a risk and get through it. Dont ever give up. Thats just my opinion.
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