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Unread 01-08-2005, 07:57
Gdeaver Gdeaver is offline
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Re: pic: Demo Transmission 222

I have always considered the 222 trans elegant compared to the brute force dog shifters common on first designs. How ever that pneumatic shifting set up is kind of a Kludge. I don't know what kind of force is needed to move the shifting shaft in and out . In 2005 the number of Hitec servos was not limited. What if you took a plastic cylinder and cut it at an angle. When the 2 halves are twisted you would get the in out motion. One servo probable isn't enough but, 2 might do it. If it works it would cut out allot of weight and eliminate the need for Pneumatics.


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Unread 01-08-2005, 13:39
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Re: pic: Demo Transmission 222

I agree gears would be cooler to have in this gearbox, but the only machine we could attempt making gears with is the CNC Mill and with limited knowledge on how to use it, the gears would be difficult to make.

The other problem with gears is that it would probably be difficult to see inside were the shifting occurs, this too may also be a problem with just "wheels" in their place.

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How ever that pneumatic shifting set up is kind of a Kludge.
Are you referring to the 2004 three speed or the 2005 two speed shifting setup?

We thought about using servos, but we just had too many problems with them in the past when using them to shift the drill motor transmissions.

Not sure exactly what you mean by cutting the cylinder at an angle?
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Last edited by team222badbrad : 01-08-2005 at 13:44. Reason: Wow, I did not know Henry was posting and he did not know I was posting, the funny part is we both posted at 1:39...
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Unread 01-08-2005, 13:39
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Re: pic: Demo Transmission 222

As far as all the extra waterjet discussion is going... we don't have access to one, a laser mill either. We were also looking into gear cutters to make our own gears once the 06 build rlls around, but we do not have one now.
The tolerances can't be too wrong, polycarb has a hardness that is measured on the Rockwell scale, so it isn't exactly going to wear in very easily, but it is after all just a demo transmission. I did like the idea of epoxy or rubber cement. We could probably use the normal tolerances with the 05 transmission plates and use the depth of the rubber cement applied to account for the missing teeth on polycard wheels.

The servo shifting idea was discussed. The shifting is definitly possible with servos, and I bet it could be done reliably with one servo per transmission, but 2 servos per side would be the only safe way to go about it IMHO. That leads to the battery drain. The servos are run entirely off of the backup battery (correct me if I am wrong) so we didn't want to take the risk of running a low backup and not being able to shift. In the end our discissions boiled down to simplicity. Powerful air BAM one way BAM the other; physical stops each way. Done.
I believe 469 used a leadscrew setup with a globe motor powering the single screw which shifted both of the joined transmissions. I also believe that 571 and 1143 used pneumatics like us. The only other team with this transmission setup is 476 (??) and I am not sure what they use.

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Unread 01-08-2005, 14:07
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Re: pic: Demo Transmission 222

I have always looked up to team 222 for the way they build their transmission. Specially the shifter.

Just like Henry pointed out before me, that you can shift with globe motors. Team 233, The Pink Team used globe motor to shift or I was told. Take a look at their machine if you get a chance. Or get in touch with someone from their team.
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Unread 01-08-2005, 19:44
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Re: pic: Demo Transmission 222

I got it. Don't bother with rubber cement or anything. Just put wide rubberbands on your polycarb/acryllic gear-wheels. Make sure you get your center to center distance right though for good contact between the rubber bands. Enough contact to hold, but not excessive friction/binding.
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