[AT] WAS: Snow Blower now Belt Dressing

[Dave Merchant]

Watch the steam guys at a show.
Standard steam practice is to cross the belt.

This does a couple things.

The 2 sides of the belt rubbing against each other
dampens out belt oscillations, and the twist kills
the lateral rigidity of a belt that has a bit of curve to it.

Crossing the belt, with the resultant reversal of direction,
may not be practical on non-reversible tractor belt pulleys,
but a compromise I've seen is to turn one end of the belt
inside out, so both top + bottom runs have a 180 degree twist.
This cancels out any lateral curve in the belt.

The most important factor is having a bit of crown on your
pulleys, but if you need more than the small amount that
was designed into the pulleys, you probably have a curved belt
or something else wrong.

Dave Merchant


At 01:51 PM 8/18/2010, you wrote:
>Alignment on a flat belt is almost a "no-brainer".  When a belt wants to 
>walk it is going toward the LONGEST distance between centers it can 
>possibly find.  It involves more than just getting the input and output 
>axles lined up, but one of the pulleys needs to have a slight crown to it 
>so the longest distance between rotating centers is always in the center 
>of the belt.  If you don't have that condition because of limitations on 
>what you can do with your belting situation, it will always cause you 
>trouble.  If you have ever looked closely at a line shaft installation, 
>you will find at least one pulley in every pair is crowned.  Cast iron 
>pulleys are made that way on purpose.  It isn't just that having the 
>parting line in the middle of the pulley was easy -- it is necessary.  We 
>had trouble keeping the flat belt on the hammer mill when we first bought 
>it and tried to power it with our John Deere.  So Dad wound several layers 
>of friction tape around the center of the pulley on the mill so it was 
>slightly crowned.  It solved the problem, and I found out at an early age 
>that friction tape isn't just for the handles of baseball bats.
>
>For those of you with band saws in your shop, look closely at the pulleys, 
>and see how changing the adjustment of the angle changes the location of 
>the saw blade as it rotates.  Belt sanders work similarly.
>
>Larry
>
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Dave Merchant
kosh at nesys.com
nesys_com at ameritech.net
dmerchant at layerzero.com

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