48MXL050, to be more exact...
All the "usual" (to me) sources seem to stop at 3/8 inch width.
COuld use two, 1/4 inch belts, but not sure this is best...
Thanks in advance / mark

In article ,
says...
48MXL050, to be more exact...
All the "usual" (to me) sources seem to stop at 3/8 inch width.
COuld use two, 1/4 inch belts, but not sure this is best...
Thanks in advance / mark


Breco can supply urethane/steel XL pitch belts up to at
least 1" wide, but I've never seen one as short as 4.8", if
that's what the 48 in your number specifies. $50 minimum,
IIRC, though you may be able to get around that by going
thru Motion Industries, etc.

http://www.brecoflex.com/home.html

I do have a supplier for wide neoprene belts as well, but
can't remember the name right now. If you're still watching
this, contact me offline and I'll dig it up.

You're correct that 2 narrow belts will not be as good as a
single belt.

Ned Simmons

Ned Simmons wrote:

You're correct that 2 narrow belts will not be as good as a
single belt.

Why? Load sharing? Multiple belt drive setups seem to be common with
aircraft homebuilders. Claim is, of course, redundency.

Ted

In article ,
says...
Ned Simmons wrote:

You're correct that 2 narrow belts will not be as good as a
single belt.

Why? Load sharing? Multiple belt drive setups seem to be common with
aircraft homebuilders. Claim is, of course, redundency.


I'm not sure I've ever actually seen it spelled out, but
for the urethane/steel belts at least, I've always assumed
it's due the fact that the reinforcing cable is spiral
wound, so that there is a loose end on each side of the
belt. This has the effect of lowering the capacity of the
belt's tensile capacity per unit width near the edges. For
the belt cited (in urethane/steel), a 1/4" belt is rated
180 lbs., the 1/2" is 420 lbs.

This probably wouldn't be of concern on an aircraft, where
presumably the drive is being designed with other factors
in mind that limit the tension in the belt to more
conservative levels.

Redundancy sounds good on an aircraft--whether it's
actually desirable would depend on what happens when one
belt lets go. Multiple belts means a higher probability of
a belt failure in a given period of time. If a separating
belt causes other serious damage or problems, then the
redundancy is probably not a good thing.

I wouldn't expect load sharing to be an issue as long as
the belts were from the same lot and checked for equal
pitch length at installation. I have seen significant
differences among different timing belt lots when installed
on pulleys with fixed centers, and no idler or other
provision for tensioning.

Please don't design a propellor drive based solely on my
advice.

Ned Simmons