Alternator belt screech mystery

[BEngo]

Another thought.  Forum member Bee has a foundry and might be able to cast a new aluminium alloy blank.  Subject to size, I can then make it into a modified version of the existing with one V groove and some poly-V grooves.

N

[dmr]

32 minutes ago, BEngo said:

Another thought.  Forum member Bee has a foundry and might be able to cast a new aluminium alloy blank.  Subject to size, I can then make it into a modified version of the existing with one V groove and some poly-V grooves.

N

Yes, I like that idea as turning from solid would take a long time and make a LOT of swarf. Shrinking another ring on is also a possibility if the second V groove was turned off first.  Its complicated as there is also an extension shaft with another big pulley on a taperlock driving the Travelpower. I would be unhappy moving the belts out any further as that would be putting even more strains onto a heavily loaded crankshaft......all this stuff is effectively carried on the original front pulley. 

 

Ive got a couple of other significant projects on just now but will look at this further a little later.  Thanks

 

..............Dave

[TheBiscuits]

2 hours ago, dmr said:

Whenever I buy a replacement for my 100 amp alternator it turns up with a multiV pulley and I have to find away to get that off and put my single V pulley on instead.

 

I would love to use a multiV pulley on the engine but its a big 13 inch diameter jobby and there is nothing available off the shelf. If anybody knows a machine shop who would make something without charging an arm and a leg......??????? 

 

...............Dave

Speak to Beta - the JD3 came with a 70A alternator as standard but there was an optional 100A second alternator.

 

I don't know how they were driven, but Beta will.

[dmr]

1 hour ago, TheBiscuits said:

Speak to Beta - the JD3 came with a 70A alternator as standard but there was an optional 100A second alternator.

 

I don't know how they were driven, but Beta will.

 

Yup, itstrhat 100ampalternator that I am running. I have had several chats with Beta about this. Their fix is to use a single "B" belt. I assume this is the same big pulley but machined out to take the wider belt, looks like there is maybe just about enough metal to do that.  They then use quite a big pulley on the alternator (which I have). This is bigger in diameter than is ideal but I assume the thicker B belt would not like bending round a small pulley....which is why I would like a polyV belt. Beta also want quite a lot of money for the big pulley and I can achieve the same result with my current A belt as long as I am very careful about getting the belt tension spot on.  Trouble is I am most likely running the alternator at just the wrong speed.....maximum amps and minimum cooling ?

 

Neil Edwards took retirement from Beta a couple of years ago so there is no longer a JD3 "expert" available to speak to, just a parts man who sells parts but does not know the history and quirks of the engine.

 

.............Dave

 

[Poppin]

Just to put this to bed... I changed the belt to a slightly more suitable one, and slightly repositioned the alternator. All seems fine. 

 

This is the 120A alternator with standard V-pulley I'm using: 

https://www.ebay.co.uk/itm/NEW-CANAL-BOAT-ALTERNATOR-HIGH-OUTPUT-120-AMP-A127i-TYPE/181430420788?epid=1260748483&hash=item2a3e188534:g:dhIAAOSwEeFVGmf9:rk:1:pf:0

 

Now, it seems that neither the engine pulleys nor the alternator have notches, so the fact that my engine has had a cogged belt since we got it seems strange. The new belt that had trouble had smaller coggs, whereas the one I'm using now has larger coggs and small spaces in between the coggs (making it is closer to a standard V-belt). I'll be picking up a standard v-belt soon.

 

Though it does seem that with this belt, and the new positoning, I'm getting more amps with no screeching, even at high revs. 

 

Thanks all for advice!

 

edit: I've just read that you can used cogged belts in standard V-pulleys, so perhaps I'll leave it.

Edited January 4, 2019 by Poppin

[dmr]

Cogged belts are good and intended for standard pulleys. The Cogs are not like the teeth on a timing belt, imagine it as a standard V belt but with notches cut in it so it can bend more easily round a small alternator pulley. As you are working your belt very hard a good cogged belt from a company like Gates will likely perform better than a non cogged belt.

Do note what the experts on here say about not working the crankshaft damper too hard, use just enough belt tension to make it work and don't be tempted to overdo it.

 

..............Dave

[Boater Sam]

I am pleased for you that you have achieved a resolution.

Belt alignment is critical when trying to transmit a lot of power.

A cogged belt of good quality will last longer than a plain belt. I would have a couple of spares handy, that belt is working very hard.

Some plant engines running big generators now use toothed belts like cam timing belts, perhaps this is the way to go as they don't need a lot of tension.