[TheForge] Flatbelt excitement

[Rick]

Hold on a minute guys -
    A v belt runs on the sides of the v, while a flat belt is driven by a 
wide surface of contact rather than a tight surface.  The older machines 
that were made for flat belts were normally made with out regular bearings, 
and with babbit.  This is not intended for the force of a side load, such as 
a tight belt would provide.  Rather the width of the belt provides 
sufficient force by friction of a wide surface.  This should be thought  of 
when discussing a changeover from a flat belt to a v belt drive, as they are 
very different animals.

Just a thought,

Rick Crawford at Rafter Lazy C
  Home of Smoky Forge and Lem the Wonder Mule
   In the middle of Northern Illinois

    http://www.smokyforge.com
     rick at smokyforge.com


----- Original Message ----- 
From: "Mike Spencer" <mspencer at tallships.ca>
To: <theforge at mailman.qth.net>
Sent: Friday, May 26, 2006 2:02 AM
Subject: [TheForge] Flatbelt excitement


>
> Of interest only if you've used flatbelt drive on something or are
> thinking of it:
>
> Live an learn.  Instead of thinking ahead, eh?
>
> I've just learned that flat belt drive can be a problem with a machine
> that doesn't maintain a load on the belt.  I hooked a horizontal belt
> up to my A&O air hammer with about a 9' gap between pulleys, good
> tension, pretty good alignment, good belt, lacing and pulleys and
> plenty of power but no tensioner idle pulley.
>
> The hammer has a crankshaft driving a quite heavy vertical piston.  On
> the upstroke, the lower run of the belt is under considerable load and
> works properly but on the downstroke, the hammer runs ahead, tending
> to slack off the lower run of the belt and pull the upper one taught.
> That starts an oscillating wave in the belt that gradually becomes
> quite um... exciting and spectacular before throwing the belt off the
> pulleys.
>
> Jeez, it's obvious, only I never thought of it beforehand.  Didn't
> appear to happen with two (much shorter and tighter) V-belts.  (The
> engine with the V-belts doesn't have enough power and the
> modified-truck flat-belt "power plant" doesn't fit into available
> space up close to the hammer.)
>
> I dunno if a tensioner idle pulley would fix it up or not.  A much
> shorter belt would probably help a lot.  Time to do gardens so I'll
> have a week or two to think about it before I get back to hands-on.
>
> Any advice or accounts of experiences dealing with machines that
> overrun the flatbelt drive would be welcome.
>
> - Mike
>
> -- 
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                           /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
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