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Unread 27-12-2006, 19:22
AustinSchuh AustinSchuh is offline
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Re: pic: 2 Speed Transmission

What part of the transmission is most likely to break? I am mostly worried that the first time that we get into a pushing match, the transmission will fail.

I am having trouble putting this next sentence in plain english, so bare with me.
When the dog's teeth just leave the face of one of the two gears with holes cut in them to accept the dog's teeth, how much clearance should I have between the dog's other set of teeth and the other gear?

Thanks for all of the feedback so far.
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Unread 27-12-2006, 19:37
Jeremiah H Jeremiah H is offline
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Re: pic: 2 Speed Transmission

<These are my thoughts, some suggestions from my experience, if some of my hypotheses are no good, please correct me>
If you want to shoot for 15 fps and your team has a good driver, I'd say go for it. Last year, we put our bot up on blocks to find its freewheeling speed, and high gear was around 14 fps. Once we got the bot on the ground, we never actually clocked it very accurately, but our rough figures said that it was running about 12 fps. You may not lose as much speed as we did, depending on the efficiency of your drivetrain and the type of wheels you use. (We ran a six wheel #35 chain drive with 4 go-cart tires and two pneumatic Skyway look-alikes. If you use smaller wheels I wouldn't think your bot would slow down as much as ours did) Ours seemed blistering fast, it was fine for '06 (the field was open and our driver was great), but I wouldn't recommend it for a playing field that has a lot of obstacles like it was in '05.
Also- two things we learned the hard way-
-make certain that the key for your output sproket/pulley is TIGHT. We had problems with shearing, yes shearing, keys off on our output because they were too lose and were getting slammed back and forth a lot due to our defensive strategy (ram, back off, repeat, etc.)
-try not to shift when your motors are under power, it tends to be hard on the dog. when we took our gearboxes apart this summer, the dogs' corners were worn worse than they should've been. Just try to shift only when the motors aren't running at full power, and I think you'll be alright.
As for the clearance, I know exactly what you are talking about, but I can't remember what ours was. I'll check the bot tomorrow and get back to you. I would reckon that 1/8 would be plenty, but I honestly can't remember.
Good luck!
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Unread 28-12-2006, 14:26
sanddrag sanddrag is offline
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Re: pic: 2 Speed Transmission

Quote:
Originally Posted by AustinSchuh View Post
I am having trouble putting this next sentence in plain english, so bare with me.
When the dog's teeth just leave the face of one of the two gears with holes cut in them to accept the dog's teeth, how much clearance should I have between the dog's other set of teeth and the other gear?
I think last year I did something like .020 neutral space. I mean, if it clears, it clears; no need to clear by a big amount. Just make sure that under no circumstances are both gears angaged at once.

Our shifting dogs went something like .13" into the gears and were something like 1" OD.
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