Pulley wheel question

[richy_B]

I need a pulley wheel for my trike build, it is just to guide the chain to prevent it from hitting the forks. The plans say use a steel V pulley, about 50mm diameter. I've also been told a flat bottom pulley with a bearing in would be better. I've asked at a lawn mower repair shop and an agricultural suppliers, neither sell anything like it. I know there is a link on here somewhere to a website that sells them. I've tried a search but can't find the thread. Any ideas where I can buy one? Thanks in advance.
Rich
Here is a picture to help explain, sadly this is not my work.

 

[rtbcomp]

Couldn't you use a sprocket instead?

 

[Lewis Medlock]

Hi richy,

Can you use the lower idler pulley thing off've a derrailleur gear?

All the best, Jim

 

[the snooper]

get to the scrap yard and take a cambelt tensioner of an engine some have a bracket on aswell or at least a hole in it to bolt it onto your bike

 

[GrahamGKD]

How does that work then Richy - from the picture it looks like both runs of the chain need to be deflected from straight? I initially thought of a tensioner from a folding bike but it looks like your deflector is working on the 'load' side of the chain, in which case a chain tensioner like fitted to a folding bike or on a derailleur wouldn't be suitable since they are only intended to operate on the return leg of the chain. I think the cambelt idler pulley suggestion from the snooper would do it. Graham.

 

[rtbcomp]

I was thinking about the cambelt tensioner idea - wouldn't the chain skid over the smooth surface?

A cambelt tensioner has a good bearing in it so would it be possible to use one as a hub for a sprocket?

 

[GrahamGKD]

I was thinking about the cambelt tensioner idea - wouldn't the chain skid over the smooth surface?

A cambelt tensioner has a good bearing in it so would it be possible to use one as a hub for a sprocket?

I see you're keen on the sprocket idea there rtbcomp

The old Ford 1.8 diesels (used in Escort vans) used to have an idler with a plastic outer which might be better? I know this because one of ours shed its plastic one day on the motorway and fairly well wrecked an otherwise decent engine! Graham.

 

[rtbcomp]

I see you're keen on the sprocket idea there rtbcomp

........

You can't beat a good sprocket!

Some older car engines with timing chains had a sprocket tensioner.

 

[reno]

How about trying one of these

They are used for stopping chain slap on cross country mtb's. From memory they can be a little noisy but I think that's more to do with the amount of muck that gets flung at them.

 

[richy_B]

Thank you for all the replies.
rtbcomp, I honestly don't know why I can't use a sprocket, from the look of the picture it may be too small a gap between the two sides of the chain and could catch.
Lewis Medlock, I'm told the derrailleur arm thingy is not strong enough, I might be able to strengthen it some how.
Snooper, that sounds like a good idea, but I will have to get my mate to do it for a couple of warm beers. I'll be honest, I wouldn't know where to start
GrahamGKD, It is to allow you to make right turns, it pushes the top part of the drive side chain away from the frame.
reno, good find there, if plan A at the scrappy fails, I could use some big washers to make some flangy things.
Thanks again.
Rich

 

[Nimbus]

In the absence of a suitable chunk of plastic to turn down I made something similar by laminating acrylic discs (larger diameter for the flanges). Tufnol is good.

 

[GrahamGKD]

In the absence of a suitable chunk of plastic to turn down I made something similar by laminating acrylic discs (larger diameter for the flanges). Tufnol is good.

I needed to make some washers and bushes for some old bike derailleur levers yesterday and managed to source some PTFE bar stock - I've not used this before but I reckon a chunk of PTFE would make a good idler pulley which would run on a steel shaft without need for a bearing. Very simple to turn up on the lathe as well. Do you have / know someone with a lathe Richy? Graham.

 

[Nimbus]

Try here http://www.directplasticsonline.co.uk/PTFERod/ for plastic stock. Take care cutting PTFE 'cos it it gets too hot it gives off poisonous vapour...

 

[chunkolini]

I have a solution.
On my tallbike I had thsi problem.The chain would have run through one of the frame elements. I had a chnkular moment and devised a solution.
I used a jockey wheel out of a deraileur, mounted on a bent bit of metal I think I made a U shape with the wheel in the middle of it and had another bent bit bolted onto the frame.

You can just see the tensioner thingy just below the bottom bottom bracket.
This has covered over a thousand miles with no problems.
You dont need the spring in the derailleur, just mount the wheel rigidly.
In mine it is on the non tensioned side of the chain.

Chunko'.

 

[richy_B]

Thank you for the suggestion with the PTFE. I don't know any one with a lathe, I've seen one in a unit opposite where I get my bits and bobs of steel from. I'll have an ask tomorrow. I went into a starter motor refurbishing place today, they gave me a V pulley off an alternator, the chap gave me two Phosphor Bronze bushes too and said. "You just need someone with a lathe". Or I may try Bearing Man
Rich
Edit to reply to Chunkolini
Thanks for the idea, the plans say not to use the derailleur, because of the lack of strength. I might do it though and be a rebel. It's turning into a nightmare! Plan B is taping some underlay on the frame and just letting them get on with it.

 

[chunkolini]

On the photo of the dandyhandy trike, why is the chain run in front of the fork?
Would it not be easier to run it either side of the fork, ie up the back and down the front.
Another thought, I have seen a sporty version of this with 24 speed transmission ie three chain rings, and a rear derailleur, amazing watching the pilot hacking through city traffic. He had the gear and brake levers mounted on the pedal/handles, he had long cable outers keeping the cables out of the way.

Chunko'.

 

[richy_B]

Would it not be easier to run it either side of the fork, ie up the back and down the front.

It has to be like that so you can make right turns, or the chain hits the frame of the trike.