"MLD" & belt drive

[mjs]

I have seen a 2-8-0 with Tsunami sound listed as "with MLD".  What is MLD?  Also is a belt drive the way of the future and is it better.

[mjs]

I'd still like to know about the belt drives.  Skip the question about "with MLD"  that was actually "W MLD" and I'm pretty sure it stands for Western Maryland.  (feel a little dumb about that one.)

[Jim Banner]

The belt drive in the 2-8-0 allows a see through look, just like the prototype.  The alternatives would have been a series of spur gears (noisy) or a right angle drive (expensive.)  These are not your rubber bands from Hi-F days - these are space age, fiber reinforced, toothed belts that run on toothed sprockets.  They are quiet, run smoothly, and affordable.  They normally outlast the rest of the locomotive 

[richG]

They are a Cog V-belt drive. Go to Google and do a search for cog v belt. I am a retired machine mechanic and I have worked with some good size cog belts. The Cog belts prevent slipping and in many applications are needed to keep all the pulleys timed. Also, much quieter than gear reduction.

Rich

[Jim Banner]

While I agree with Rich that "cog belt" is another name for "toothed belt," "timing belt," "synchronous belt" etc., I do not agree that the toothed belt used in Bachmann's 2-8-0 is a "cog V belt."  For one thing, it has straight sides.  For another, it does not rely on friction between the sides of the belt and the sides of the pulleys to transmit power.  It is a narrow flat belt that relies solely on the mesh between the teeth (cogs) on the inner side of the belt with the teeth (cogs) near the outer edge of the pulley.  This is very similar to a chain drive system in that the drive is positive (no slippage) and the special toothed pulleys are sometimes incorrectly referred to as "sprockets."  Mea culpa on that one!

As I understand it, cog V belts were developed from regular V belts by notching the inside edge of the belts.  This allowed them to bend more freely around their pulleys, reducing power loss and reducing (but not completely eliminating) slippage.  Adding cogs to the base of the pulley grooves can completely eliminate slippage but I have no idea how common that is with V belts.  I hope Rich will tell us.  My experience as an instrument maker was at the opposite end of the size scale than Rich's, and I bow to his superior knowledge in the area of "monster belts."

For those who have never seen the inside of a Bachmann 2-8-0 I have included a photo showing the motor c/w toothed pulley and flywheel, the counter shaft c/w toothed pulley and worm gear, the toothed belt and a penny for size comparisons.

[Loco Bill Canelos]

Jim,

Thanks for the great picture!!!!    What a great way to illustrate the way it looks & works!!!

[richG]

Hi Jim

Nice photos. This will be a help to many people. The cog arrangement can be seen in the PDF document if you know what to look for.
I was not completely correct concerning the cog belts. Most of what I worked with were Timing Belts, same principle. Just nearly square teeth. Some mechanics use the term Cog or Timing interchangeably.
I used a few Cog V belts. They were mostly to prevent slipping instead of timing. Timing can be very important in many applications such as over head cam engines where timing is very critical.

Rich

[Jim Banner]

You're welcome Bill.  I just happened to have a 2-8-0 in pieces on my work bench.  It is almost new but had a flaw in the casting which let one of the counter shaft bushings spin and destroy itself.  So I am making a special bushing for it.  Cheaper and easier than sending it back on warranty.

I use a simple trick to take photos of small items.  I was lucky enough at a garage sale last summer to pick up a lighted magnifying glass for a couple of bucks.  It was missing a couple of minor bits of hardware but was otherwise brand new in the box.  Clicking on the link will show you the sort of thing.

http://www.artsuppliesonline.com/catalog.cfm?cata_id=7806

With the object on a piece of paper under the lens and the camera looking down through the lens, it is easy to take an almost shadowless closeup photo.  The camera is nothing special.  It is a Kodak digital that cost less than $100 and is overkill for the job.

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Rich, you and I rarely disagree but I like to think that when we do, we both behave like gentlemen.  And we both keep learning from one another.

[richG]

Hi Jim

Thanks again for that heads up. I have one of those magnifiers but never gave it a thought for pictures.
Now to find it.

Rich