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intermitent gear set Question
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Posted by: daved

02/24/2004, 13:28:02

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I am developing a toy that has a special set of spur gears that create intermitent motion. There is a large driving gear (64 teeth) and a small pinion gear (8 teeth) that are spaced to mesh perfectly. The large gear has 48 teeth removed so that it only engages the pinion 1/4 of the time. It rotates at 2RPM and as it comes around it engages with the pinion, causes it to rotate twice and then continues on free of the pinion until it comes around again. My question: Do you need to modify the first few teeth on the big gear that engage with the pinion? I had heard that making the first tooth 1/2 height and then removing the second tooth would insure good engagement. Is that true?



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Re: intermitent gear set
Re: intermitent gear set -- daved Post Reply Top of thread Forum
Posted by: RandyKimball
02/24/2004, 15:25:58

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What you are talking about is called blocking the leading and trailing teeth. Yes you simply file them flatter at a progressive angle. The first one to about 1/3 the full height and the forth or fith tooth would be the normal height. In other words (as this could be misunderstood) you just file off the group at an angle with a few strokes of the file. THEN you break the top new edges of these new teeth tops a bit to invite the pinion to seek a seat as it comes into mesh. The edge breaks you file cause the tops of the new areas (the peaks) to be similar in width to the regular teeth. Clearly you won't be able to file the peak of the first tooth to be as sharp as the normal teeth, but to a fairly sharp peak point. This works in the same way as the synchronizers in a manual transission. The most important reason is to discourage the pinion from climbing over the teeth flats.


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Modified by RandyKimball at Tue, Feb 24, 2004, 21:13:34

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