Alternator belt around flywheel...

[casper ghost]

I'm fitting my alternator off my flywheel which has a 22.5" diameter. The alternator has a pulley on with 4 groves.

I need a belt to fit that is rather long, needing to be 6' long in a circle.

I know loods of boats run their alternator this way so where can you get these long belts from?

 

Thanks, Casp'

 

Edited as I can't type...

Edited July 10, 2010 by casper ghost

[nb Innisfree]

I'm fitting my alternator off my flywheel which has a 22.5" diameter. The alternator has a pulley on with 4 groves.

I need a belt to fit that is rather long, needing to be 6' long in a circle.

I know loods of boats run their alternator this way so where can you get these long belts from?

 

Thanks, Casp'

 

Edited as I can't type...

 

You could try these It says emergency use but they can be used on a permanent basis.

Edited July 10, 2010 by nb Innisfree

[casper ghost]

You could try these It says emergency use but they can be used on a permanent basis.

 

I've had a look but none of them is the right type. The pulley takes a belt that is quite flat with 4 little v's along it's length. I hope it isn't going to cost me as much as the ones on your link...

Casp'

[Priston]

I've had a look but none of them is the right type. The pulley takes a belt that is quite flat with 4 little v's along it's length. I hope it isn't going to cost me as much as the ones on your link...

Casp'

 

Try either Fenner Power, they are suppliers of industrial bels of most sizes and configurations. OR Google for GATES who are the probably largest manufacturer of belts, if you look up there style, and industrial belts you should find the part number that you are looking for. Most large motor factors will be able to supply Gates, providing you know what part number you are looking for, although it may take a fewe days for them to get it in.

[nb Innisfree]

I've had a look but none of them is the right type. The pulley takes a belt that is quite flat with 4 little v's along it's length. I hope it isn't going to cost me as much as the ones on your link...

Casp'

 

Sounds like you have poly vee belt pulleys. They should be available, washing machines use long ones.

[casper ghost]

I've looked up the sites, it's a trawl through loads of stuff, but you seem to need to know what part number you want and of course I don't know that. What I need is a place I can walk in with the pulley and say this is what I want.

It's all hassle..

Casp'

 

Edit, just thought of a mechanics near me who specialises in reconditioning starter motors and alternators, bet he would know.

Edited July 10, 2010 by casper ghost

[Eeyore]

I've had a look but none of them is the right type. The pulley takes a belt that is quite flat with 4 little v's along it's length. I hope it isn't going to cost me as much as the ones on your link...

Casp'

Hi Casper

The normal automotive "flat/polyvee" belt is know as a "PK" format belt. (as in the the shape and size of its cross section; or if you like, what it looks like if you cut through one.)

The one you require will be described as 4PKxxxx, where xxxx is the required length in millimeters.

A lot of makes use this basic description on the belt, but of course others have thier own numbering system.

The basic description should however give you a match for most makes.

Steve

Edited to add:

You may need to fit an idler pully to increase the "wrap/contact arc" on the alternator. I have some experience with Vee belts used this way, which makes me think that slipping could be a problem on larger alternators - of more than 50 amps, or there abouts.

Edited July 10, 2010 by Eeyore

[rjasmith]

A place you could try is Brammer UK (look at their website for your nearest branch). Our local one (Guildford) is always quite helpful to go into and ask for assistance over the counter on the subject of belts, pulleys and bearings etc. I never buy belts etc from original equipment mfrs (eg for things like the garden tractor) as the spares mark up is generally greater than from a specialist distributor.

 

Richard

[koukouvagia]

A place you could try is Brammer UK (look at their website for your nearest branch). Our local one (Guildford) is always quite helpful to go into and ask for assistance over the counter on the subject of belts, pulleys and bearings etc. I never buy belts etc from original equipment mfrs (eg for things like the garden tractor) as the spares mark up is generally greater than from a specialist distributor.

 

Richard

 

Another good place is Binney's, Coventry .

 

I seem to remember I measured the size of belt I needed with a piece of string, emailed the measurement and hey presto, the belt arrived next day by post.

[casper ghost]

You may need to fit an idler pully to increase the "wrap/contact arc" on the alternator. I have some experience with Vee belts used this way, which makes me think that slipping could be a problem on larger alternators - of more than 50 amps, or there abouts.

 

Thanks. It's a 70 amp alternator. Is an idle pulley one that just pushes the belt a bit to narrow the angle to the alternator pully?

There is a Brammer fairly near to me so maybe i'll wonder in and see what they can do.

 

Casp'

[nb Innisfree]

Thanks. It's a 70 amp alternator. Is an idle pulley one that just pushes the belt a bit to narrow the angle to the alternator pully?

There is a Brammer fairly near to me so maybe i'll wonder in and see what they can do.

 

Casp'

 

You could adapt a cam belt tensioner from a scrapyard, fix up on the alt bracket to bear on the back of the belt.

Edited July 10, 2010 by nb Innisfree

[tony collins]

Try any industrial bearing supplier. They have contacts in power transmission and links to most suppliers. Bear in mind that automotive belts are built to different standards to industrial belts.

 

If you ever find yourself in Rugby there is a brilliant supplier of belts of all types in Hunters Lane, they have literally thousands in stock. It is called Arrow Engineering Supplies. If you NOW have an idea what you need try their website, www.fasteng.co.uk

 

If you do visit them ask for John in the warehouse, if he can't help, nobody can.

 

Tony.

[Eeyore]

Thanks. It's a 70 amp alternator. Is an idle pulley one that just pushes the belt a bit to narrow the angle to the alternator pully?

Casp'

Yes thats right.

Good advice from nb Innisfree.

A suitable width sealed bearing would also do the job. (Tony beat me to it!)

Both routes will require you to adapt or make a bracket to support the idler.

Steve

Edited July 10, 2010 by Eeyore

[casper ghost]

Yes thats right.

Good advice from nb Innisfree.

A suitable width sealed bearing would also do the job. (Tony beat me to it!)

Both routes will require you to adapt or make a bracket to support the idler.

Steve

Do you think I need to fit an idler straight away or is it worth trying without one?

Casp'

[Timleech]

Do you think I need to fit an idler straight away or is it worth trying without one?

Casp'

 

Try it without but look up how to set the tension correctly, it's fairly important with these belts.

 

Tim

[nb Innisfree]

Do you think I need to fit an idler straight away or is it worth trying without one?

Casp'

 

Your large 22.5" pulley is 5' 10" circumference so your alt pulley must be quite small and close to crank pulley. In this case you would be getting minimal 'wrap' on your alt pulley which makes me think you will be better off with an idler.

[Timleech]

Your large 22.5" pulley is 5' 10" circumference so your alt pulley must be quite small and close to crank pulley. In this case you would be getting minimal 'wrap' on your alt pulley which makes me think you will be better off with an idler.

 

Agreed, if the 6' is to be taken literally, the alternator pulley must be almost rubbing on the flywheel!

If you go down the tensioner route, remember to allow extra length on the belt to give greater wrap on the alternator pulley, without it you're losing the main benefit. The alternative is to have a longer belt and move the alternator further away.

Or both.

 

Tim

[sharpness]

I need a belt to fit that is rather long, needing to be 6' long in a circle.

 

Thanks, Casp'

 

The wifes tights are no good then, her legs aren't that long, shame.

 

Steve

[tony collins]

Agreed, if the 6' is to be taken literally, the alternator pulley must be almost rubbing on the flywheel!

If you go down the tensioner route, remember to allow extra length on the belt to give greater wrap on the alternator pulley, without it you're losing the main benefit. The alternative is to have a longer belt and move the alternator further away.

Or both.

 

Tim

 

For got to mention earlier. If you fit an idler it should be fitted to the "slack" side of the drive. In other words, as the belt is pulled round the driven pulley, (alt) it will create tension therefore a "tight" side. if an idler is fitted to the drive at this point it will reduce the effectivesness of the drive. It follows that the other side is the slack side and where the idler should be fitted. A polyvee belt will tolerate angles of wrap around the small pulley down to 90 deg, (this is much less than other types of belt) but the lower then angle of wrap, the lower life expectancy of the belt.

 

See the sketch below.

 

 

Tony.

Edited July 11, 2010 by tony collins

[casper ghost]

See the sketch below.

 

Tony.

 

You've even drawn that the right way for my setup.. The engine doesn't have an alternator now so no bracket etc, therefore I could position it wherever I wanted so moving it further away is no problem. I take the point about , not much wrape around, i'll have a look at a car tensioner as suggested earlier. I can see that as with most things it's not as simple as I had hoped..

Casp'

[nb Innisfree]

You've even drawn that the right way for my setup.. The engine doesn't have an alternator now so no bracket etc, therefore I could position it wherever I wanted so moving it further away is no problem. I take the point about , not much wrape around, i'll have a look at a car tensioner as suggested earlier. I can see that as with most things it's not as simple as I had hoped..

Casp'

If tensioner is positioned away from both pulleys you may need to provide it with some 'shoulders'? to stop belt wandering sideways and slipping off, fitting tensioner near to a pulley would prevent this. I have a cambelt tensioner (pictured) from an older Ford Escort which is quite simple and is already mounted on a handy bracket. Others may be similar or better

 

[casper ghost]

If tensioner is positioned away from both pulleys you may need to provide it with some 'shoulders'? to stop belt wandering sideways and slipping off, fitting tensioner near to a pulley would prevent this. I have a cambelt tensioner (pictured) from an older Ford Escort which is quite simple and is already mounted on a handy bracket. Others may be similar or better

 

I hope I can find one that is ready to go like yours, that would make fitting fairly easy. I'll try it without shoulders first and see if it works. Now for a trip to the scrappy..

Casp'

[nb Innisfree]

I hope I can find one that is ready to go like yours, that would make fitting fairly easy. I'll try it without shoulders first and see if it works. Now for a trip to the scrappy..

Casp'

 

I love a scrappy, if I come up on the Lottery I will buy a big canalside one with moorings where boaters can come to scrappy parties and indulge their (construction) fantasies in a big covered workshop. In the winter there will be a huge SF stove banging away with sausages sizzling away and good hand washing facilities after getting them oily.....

 

Wake up!

Edited July 11, 2010 by nb Innisfree

[tony collins]

I hope I can find one that is ready to go like yours, that would make fitting fairly easy. I'll try it without shoulders first and see if it works. Now for a trip to the scrappy..

Casp'

 

You may not need shoulders as I understand that both pulleys have grooves in them. But alignment needs to be pretty good. In a standard Vee belt drive however, I have seem some horrendously out of align drives working, albeit at a high cost in beltlife (and noise).

 

In a timing belt drive for example, it is usual to fit flanges only to the small pulley. Of course the flat belt drives of old had no flanges at all, relying on the "crowning" of the pulleys to keep the belt in place.

 

Tony.

[Grunge]

May be worth also considering what speed your alternator will run at, as the intended drive pulley will give a really high pulley ratio.

From memory the A127 type alternators are ok up to about 15000 r/min max, but above 6000 r/min give very little more output.