Alternator/pump/fan V Belt Types?

[alan_fincher]

Can somebody please explain in simple terms, or point to a link that does, how the sizing and fit of typical V belts works.

 

I have had boats that use both a belt of either 9.5mm or 10mm width, (I was never quite sure if these were the same thing really), but both current boats drive the alternator with a ribbed V belt 13mm wide.

 

However it seems that apart from width across the belt, other factors like it's "depth", and hence the angle of the sides come into play.

Some places appear to sell multiple V belts with the same quoted dimensions, and from the same manufacturer, but at significantly different cost from the same supplier. Clearly something differs, but I couldn't work out what, or how you would know what was best for you.

 

So if I know my belt is a V type, 13mm wide and ribbed, what else apart from the length do I need to know when sourcing a replacement, please?

 

If you tried running a 13mm ribbed V belt in a pulley designed for a 10mm one, is that a complete "no no", or could it work at least for a while?

[Boat&Bikes]

I always assumed that 10mm and 13mm were based on 3/8 inch and 1/2 inch belts. As for running 13mm in 10mm pulleys it's fine as long as top of the belt is inside the pulley faces. Pulley belts are not precision items. Ian .

[Eeyore]

Can somebody please explain in simple terms, or point to a link that does, how the sizing and fit of typical V belts works.

 

I have had boats that use both a belt of either 9.5mm or 10mm width, (I was never quite sure if these were the same thing really), but both current boats drive the alternator with a ribbed V belt 13mm wide.

 

However it seems that apart from width across the belt, other factors like it's "depth", and hence the angle of the sides come into play.

 

Some places appear to sell multiple V belts with the same quoted dimensions, and from the same manufacturer, but at significantly different cost from the same supplier. Clearly something differs, but I couldn't work out what, or how you would know what was best for you.

 

So if I know my belt is a V type, 13mm wide and ribbed, what else apart from the length do I need to know when sourcing a replacement, please?

 

If you tried running a 13mm ribbed V belt in a pulley designed for a 10mm one, is that a complete "no no", or could it work at least for a while?

From a previous thread on this subject http://www.products4engineers.nl/resources/upload/mBjbab-pdf.pdf

Edited June 3, 2016 by Eeyore

[alan_fincher]

From a previous thread on this subject http://www.products4engineers.nl/resources/upload/mBjbab-pdf.pdf

 

Ah, I failed to find anything like that - thanks for pointing it out.

 

Far more information than I can fully absorb, but if I'm understanding a letter seems to be used that indicates the belt width....

 

Z = 10mm

A = 13mm

B = 17mm

C = 22mm

D = 32mm

 

Presumably when I see references elsewhere to a "Type A" belt, but with no explanations, this is what is being referred to?

It would appear from my limited understanding that these usually have a standard profile, so provided the belt width matches the pulley, I think in simple boat applications you would normally not have a lot else to worry about.

 

Unfortunately I now discover that a typical alternator for boat use sold on eBay comes with a 10mm pulley as standard, (assuming there is one at all). So far three suppliers that have replied all say that is the only size they can supply, so if you want to swap it to a wider one, you would have to acquire that separately and arrange swapping over yourself.

 

Perhaps I'm asking the wrong kind of supplier. Would someone who sells alternator usually be expected to have different pulleys available, or, if not, where would I go to source the pulleys?

[pearley]

This may be of use

https://www.google.co.uk/search?q=drive+belt+dimensions&client=tablet-android-lenovo&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj0zeeVmIzNAhUfOsAKHX3KC6IQ_AUICSgC&biw=962&bih=601#imgrc=0vUHEmAzVZfhQM%3A

 

When we installed vehicle air conditioning for a living, for some applications the AC manufacturers supplied an 11mm wide belt. This was for vehicles where you couldn't replace the crank pulley. It just sat in the groove and could transmit the extra power required by the compressor. The alternator was then driven from the spare groove on the compressor which, although made for 13mm belts was obviously deep enough to accommodate the thinner belt without bottoming out.

Edited June 3, 2016 by pearley

[adrianh]

The angle of a vee belt is standard, the specified dimension is the width at the top, the thickness and construction of a belt can vary depending on its design/usage.

Automotive (ie small engine boat ) belts are generally Z style and can be notched so they work better on small pulleys and run with less heat build up at high speeds.

The angle of a vee belt pulley changes according to the diameter of the pulley, what is important is that any belt is running on its side faces and not touching the base of the vee groove.

I have made pulleys in the past, machined from steel, but you are limited on the minimum size for larger belt profiles to work properly and it is a guess to get the correct angle.

I don't have pulley info to hand at present, look at transmission developments web site for info on standard sizes.

PM me if you need any help

[Theo]

Don't forget that there are wedge belts as well a V belts. When comparing them you can see the difference: the wedge is deeper than the V. They are not, stictly speaking, interchangeable but I suspect that you could get away with it for quite a long time.

 

Theodora has a triple wedge belt drive from the gear box to the prop shaft.

 

N

[Alan de Enfield]

Maybe just fortunate but my 'belts' still had a visible part number on them so I could order spares to match.

 

The part number is "A1530 / 13 x 1500 A59"

 

I was told by the supplier that the "A59" tells them everything they need to know about the profile (width, side angles, depth) and then they just need the length (ie 1500mm)

[alan_fincher]

Yes, some belts are very usefully marked, but others are not, even when new it seems. This boat came with a m arked belt on the engine, but equally another belt left on board (and apparently brand new) is only marked on its packaging.

[David Mack]

Maybe just fortunate but my 'belts' still had a visible part number on them so I could order spares to match.

 

The part number is "A1530 / 13 x 1500 A59"

 

I was told by the supplier that the "A59" tells them everything they need to know about the profile (width, side angles, depth) and then they just need the length (ie 1500mm)

I think A59 also tells them the length - 59 inches which is near enough 1500mm. I think the 1500mm is the length at pitch radius, and the 1530 is the length over the outer surface.

[Alan de Enfield]

I think A59 also tells them the length - 59 inches which is near enough 1500mm. I think the 1500mm is the length at pitch radius, and the 1530 is the length over the outer surface.

 

Interesting, thanks.

That's todays 'nugget' filed away.

[jmacg]

We had to replace both the 'conventional' alternator belt and the v-belt driving the 230v alternator earlier this year after one shredded itself as we cruised along. "Europarts" (in Nottingham where our incident happened, but they have branches all over) were informative and helpful when we turned up with our mangled items. (We then bought 2 of each, so now we have spares - as we always should have done in the first place.) RCR who came out to the breakdown had almost literally hundreds of different lengths, shapes and profiles of belts on their van, so maybe it's now not altogether straightforward. The replacement 230v alternator V-belt for the Travelpack on our Beta engine is the same spec as a belt off some VW car engine or other. Europarts are good!

Edited June 4, 2016 by jmacg

[Keeping Up]

It doesn't help that different manufacturers quote either the internal or external dimension without always saying which it is. When we lost a belt on the Severn I was dismayed when my spare didn't fit even though it was marked the same size as the original. I later took both into a motor factors in Gloucester and they brought two apparently identical belts out of their stores, only to find that one matched my broken belt and the other matched my unusable belt.