Craig,
I have found the flat cam belts on the goldwing motorcycles very strong and cheap. The engines get damaged in wrecks so you can obtain the pulleys from the wreckers. You do not want a crown on the drive/driven pulley, only on the idler which runs on the back side of the belt. Any spring loaded idler off of any automobile will do the job.
--- In electricboats@yahoogroups.com, Craig Carmichael <craig@...> wrote:
>
> Recently drive systems - belts and chains - were being discussed.
>
> I'm becoming increasingly excited by the properties and possibilities
> of flat drive belts.
>
> So, FWIW:
>
> Flat drive belt systems simply need enough grip on the pulleys not to
> slip, and then they're almost 99% efficient through most of the power
> range - better than any other type. Wikipedia says that with 'modern
> materials', thin flat drive belts operate with reasonable belt
> tension and transfer up to 100 HP per inch of width. (Larger pulleys
> obviously will have more grip on the belt than small ones.)
>
> I've been searching, rather fruitlessly, for satisfactory "modern"
> flat drive belts. It has just occurred to me that the black
> polypropylene strapping one buys off rolls in various widths at, eg,
> fabric shops, is very strong with little stretch (like the yellow PP
> ropes), flexible enough to go around the smallest pulley virtually
> without friction, and cheap. (How about a 1" x 40" drive belt for
> 1$?) If the PP cloth has insufficient 'grip' without excessive
> tension, it can probably be increased by spraying it with urethane,
> or maybe some sort of rubbery material. (Urethane flat belts are
> relatively common as flat belts go, but are elastic. Urethane paint
> spray cans are common.)
>
> The ends could be melted, glued or sewn together to form a continuous
> drive belt.
>
> Flat drive belts auto-center on slightly "barrel" or "egg" shaped
> pulleys, always running towards the highest spot. I'm making ABS
> pulleys for 1" flat belts on my 3D printer, but may start molding
> them from (what else?) PP-epoxy composite to get bigger ones than I
> can print (~7" O.D.) - which will also be very tough and strong. (A
> sanded plastic pulley has more grip than a metal one and causes
> little belt wear - I'm sure it's part of the key to using flat belts.)
>
> And a clutch or (spring tensioner) can easily be made with an idler
> pulley on a spring, pressing on the outside of the belt.
>
> Finally on a rather unpleasant safety note, I would think that a hand
> caught in a flat belt and dragged through a pulley with no sides
> would probably emerge much less mangled than with a V-belt, toothed
> belt or a chain drive. (Especially if it's one that's tensioned with
> a spring.) (I mention this point as I've seen but thankfully not
> experienced savage accident results with both V-belt and chain drives
> in people I've known.)
>
> Cheers,
> Craig
>
| Reply via web post | Reply to sender | Reply to group | Start a New Topic | Messages in this topic (30) |
No comments:
Post a Comment