Path: ...!feeds.phibee-telecom.net!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: no@no.no (James Waldby)
Newsgroups: rec.crafts.metalworking
Subject: Re: Timing belt drives
Date: Mon, 2 Sep 2024 17:27:03 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 33
Message-ID: <vb4sh6$2uaie$1@dont-email.me>
References: <90c5djpacm2j9ob6qjt6dhthcnvqab1e87@4ax.com>
Injection-Date: Mon, 02 Sep 2024 19:27:03 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="cf34452785f6b29aa43a040a8185a482";
	logging-data="3091022"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/NDBQuwUw/nuRedlsRAhMf"
User-Agent: tin/2.6.2-20220130 ("Convalmore") (Linux/5.15.0-119-generic (x86_64))
Cancel-Lock: sha1:EFLc+UUfUJXoPHuOxOLbN8x/N3I=
Bytes: 2589

Clare Snyder <clare@snyder.on.ca> wrote:
> 
> Any of you guys have experience with timing belt drives? I need as
> compact as possible 1 1/2:1 reduction from a 600 rpm  2.5HP engine
> (3600 crankshaft RPM with 6:1 reduction) then another 1 1/2:1 after
> that (so lower speed higher torque) ( total reduction 13.5:1).This
> will be driving a 20 inch diameter 2 inch wide tire/wheel.
> 
> How wide and how large do I need the small sprocket? For simplicity I
> would likely like both stages identical. This simplifies everything
> including tensioning

I've seen some timing belt power transmission calculators online,
which account for RPM, small pulley diameter, required torque, etc,
but haven't done a design.  The `AI Overview` from a google search for
`timing belt drive power sizing` has about 6 bullet points, each with
a link, that get to some design webpages or calculators.

I think an auto engine timing belt handles 15 to 25 HP, which you
could scale down from or get parts from.  Depending on what your app
is maybe one stage of planetary gear reduction as in drill motors
would work; and there are some inexpensive electric bike clutches that
look like 4"-diameter planetary drives but might be irrelevant -
https://www.amazon.com/AMLESO-Electric-Planetary-Clutch-Motor/dp/B09XVL1NV7
- besides having nylon gears.

> Small sprocket on output shaft  driving large sprocket on jackshaft
> turning small sprocket driving large sprocket spinning on output shaft
> of the engine/gearbox  with wheel attached to that sprocket. Distance
> from center of small sprocket to outside of large sprocket cannot
> excede 7 inches.
> 
> Is this possible/feasible???