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custom gear for timing belt: how to design?

I'm using a timing belt for an unusual application: I'm driving it inside out, with the teeth on the outside. The belt still rides on normal idler rollers, but I have several belts side by side, which need to be in sync. For this reason, I'd like to drive it via the timing belt itself, using a gear, as opposed to using a driver roller on the inside, just in case slippage occurs and the belts go out of sync. Normally this still wouldn't be a problem, I could drive them all with a mating (wider) belt that runs off of a drive roller, or off of one long spur gear. The problem is that due to space limitations, I have room only for a relatively small gear, so only one or two gear teeth will be making contact with the belt at any given time.

The amount of power transmitted is not a major concern, mostly I want to just move the belts in a synchronized manner.

Any suggestions? Even if you don't have a solution, I would be thrilled with as much as a suggestion on what factors are important in gear design, so I can at least try a scale model and see what happens. Currently my best guess design consists of a gear with eight small teeth and gaps between teeth that are about 2 1/2 times the width of the tooth. This design permits one tooth to start making contact with the belt just as the previous tooth is letting go. I don't know if having such a large amount of air space between teeth is potentially going to cause problems however...

Thank you very much! Joe

Reply to
Grad_x
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Have you considered using timing belts with teeth on both sides? If I'm picturing things right, some of your idlers become drivers.

Dodge calls them Dual Dyna-Sync, but there are plenty of other mfrs. Here's an example of one in urethane:

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Ned Simmons

Reply to
Ned Simmons

Browning, er make that Emerson Power Transmission makes what is known as a "double gear belt" with the same teeth on the inside as the outside which would allow you to drive it using a conventional toothed sprocket. They come in XL (1/5" or .200" pitch-1/4", 5/16" and 3/8" widths), L (3/8" or .375 pitch-1/2", 3/4" and 1" widths) and H (1/2" or .500 pitch-3/4", 1", 1 1/2",

2" and 2 1/2 widths) cross sections. In the catalog I have (DC98 Condensed) there is a nice section about application and power transmission fundamentals with drive tables (center distances). You might want to start there. If power transmission really is NOT the problem, then you might want to look in the catalog of SDP (Standard Drive Products
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) which has a number of nice, off the shelf drives that most likely will do what you want. If you still need help, send me an email with more specifics and I might be able to help you size or fashion a drive. R. Wink

Reply to
R. Wink

consider using "ball chain"-- round plastic or steel balls linked with cable. Berg, among others, sells it

Reply to
Michael

I'll second browsing through the SDP site and using their components - I've used their gears, pulleys, belts, etc. in numerous prototypes over the years and their quality is first rate. Their hardcopy catalogues also include fantastic reference sections. V8Z

"double gear belt" with

it using a conventional

3/8" widths), L (3/8" or
1/2", 2" and 2 1/2

application and power

want to start there.

look in the catalog of SDP

the shelf drives that

be able to help you size or

Reply to
v8z

Joe,

Stock Drive Products gives away some very cool design manuals for free.

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Have you tried them yet?

-Mike

Reply to
Michael Munroe

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