Ratchet wheel

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tetramachine
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Re: Ratchet wheel

Post by tetramachine » Fri May 14, 2021 6:30 pm

When you are buying metals for small parts like the Ratchet wheel, just buy the easiest material for the job. As already stated A-1, W-2, D-2, all can be heat treated directly, no case hardening needed. Heat it cherry/orange, set it aside to cool to 150 +, then temper at a straw color, set it aside, done.
Is it perfect nope, Will it last 100 hours of use per year, the pawl will wear out 4 times first.
My wheels don't slow me down

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gwrdriver
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Location: Nashville Tennessee

Re: Ratchet wheel

Post by gwrdriver » Sat May 15, 2021 9:08 am

Make the pawl from the same material, treat it similarly, and the ratchet will last a few lifetimes.

A note on teeth . . . there's a practical limit to the number of teeth that should be put on the wheel, you can make the tooth pitch TOO fine such that if the teeth clog, or pawl isn't sharp and/or well-sprung, it can skip teeth. But within that reasonable limit, more teeth you put on the wheel the finer oil delivery adjustments you'll be able to make at the crank arm.
The next question should be, "Do you have a formula for tooth pitch vs wheel diameter?" My answer is, there may be one somewhere but I don't know about it. IMHO the tooth profile (and that of its mating pawl) should be the same regardless of the wheel diameter, so that a 3/8" diam wheel might have 30 teeth of a given tooth profile and a 1/2" wheel would have about 40 teeth of the same profile.
I'll take a look at a few wheels I've made today to see what the tooth profile I used is.
GWRdriver
Nashville TN

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Carrdo
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Re: Ratchet wheel

Post by Carrdo » Sat May 15, 2021 10:52 am

Actually, the lubricator ratchet wheel should have an odd number of teeth (LBSC specified a 35 tooth ratchet wheel on many of his designs). You do not want to have an even number of teeth in order to even out the wear on each tooth with usage. If you set the ratchet wheel swing arm and pawls to engage every second third or fourth tooth for example, with an even number of teeth, (say 36), every second, third and fourth tooth will receive all of the wear.

Kimball McGinley
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Re: Ratchet wheel

Post by Kimball McGinley » Sat May 15, 2021 11:38 am

What gwdriver describes about a standard tooth size regardless of wheel diameter is known in gears as the "diametral pitch". In ratchets and wheels, one pawl could perfectly fit almost any diameter of wheel. Carrdo's mention of an odd tooth number is also often used in gearing to avooid same-tooth wear and is known as a "hunting-tooth" ratio.

John Hasler
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Re: Ratchet wheel

Post by John Hasler » Sat May 15, 2021 1:09 pm

Your rachet wheel needs a tooth number with a smallest factor larger than your largest swing arm setting, not just an odd one. A 35 tooth wheel will suffer uneven wear engaging on 5 and 7. 31 and 37 would be preferable to 35.

For gears the tooth counts need to have no factors in common (that is, be relatively prime).

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gwrdriver
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Re: Ratchet wheel

Post by gwrdriver » Sat May 15, 2021 2:09 pm

The last set of wheels I made, which was a few years ago, were 1/2" O.D. and have 29 teeth. I hadn't seen them in some time and my impression now is that tooth count borders on being too fine and could easily be reduced to say 25, for that diameter.
GWRdriver
Nashville TN

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squandt
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Re: Ratchet wheel

Post by squandt » Sat May 15, 2021 2:44 pm

I am very glad to have all the information that you all have written, I am sure that there are other's who are able to use the information too.
stay on the shine side of the rail

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