Srtaight Cut drops V Standard Helical ?
Turbo Mini Forums

Interesting coincidence....
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=248747

Schrödinger's cat - so which one am I ???

Back to this again

Schrödinger's cat - so which one am I ???

What you need is some Lignum Vitae.

I still find 50 year old pumps in the fens with this bearing material.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

rods here is a link to a local company that sells vespel it is craze price and they only do it 1 inch OD :( out of my league I think !!

Paul,

Link's missing.....

There's a few potential suppliers in mainland UK but before I persue it, I want to see if Dave has any comments.

It's got me looking at other "plastics" though, which may not be so expensive.

Schrödinger's cat - so which one am I ???

sore rod link
http://radionics.rs-online.com/web/search/...oduct&R=4083920

ybh it looks very intresting but helish expensive

Got it...

RS (UK) do it too - never thought of them - better price over here but still Mega...

However, if you pro-rata that up to 40mm (based on volume) and assume you could part it off with a 2mm tool, thats 42 washers per rod so £16 each at UK RS price..... MiniSpares price for a standard one is £12 !!!

I'm sure it will be available from someone in 40mm dia and RS are always expensive, so I reckon I can better that price.

I've been through the data sheets and the only minor downside is it's aggressive (wearwise) to aluminium so couldn't be used free floating as per the standard washers, but would need to be pinned to the alloy housings. A simple 3mm roll pin should suffice.

But, as I said earlier, I'll wait to see if Dave has any comments before getting too serious - I've been shot down in flames already so I'm sure to have overlooked something obvious here too !!! Just waiting to find out what !!!

Schrödinger's cat - so which one am I ???

How about one of these:



Much higher loading than the deep groove ball.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

How would you keep the two part inner race clamped together ???
That kind of bearing is designed to go an a shaft where the inner parts are trapped/compressed.

Schrödinger's cat - so which one am I ???

Edited by Paul S on 10th Oct, 2008.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

The figure of 18 is thinking of the naughty boys with their K-headed engines and silly RPM's.

As regards vespel - well, it's pretty much the ULTIMATE as far as capabilities go, but it is also the ultimate in price.

The one consideration is it is not ductile, not in any sense of the imagination. high impact forces fracture it - hence if you have a helical gear with a lot of axial movement, you could potentially fail a vespel thrust washer on a clutch dump (say a drag-strip start).
We've not used them in any transmissions, but our clutch division has used them for applications where the ultimate is needed, and the high unit cost can be tolerated for the gains the material provides.

I imagine the lack of ductility would mean you'd have to allow it to spin freely - between the two surfaces as tangs or other 'rotation preventers' would be a failure point waiting to happen. This of course means that a housing that is already even slightly chewed up wouldn't be suitable...

what about alowing the vespel to spin freely but put a steel trust washer between it and the alloy caceing and fix it with a driving peg or dowl how would that sound so the vespel would be protected by the washers !

Edited by PaulH on 10th Oct, 2008.

yes - sounds like a plan... this would also allow you to save money on the $$$$ vespel by making it thinner...

I have a chat with a materials specialist on Monday and see what kind of options we can get Vespel in what would be the best size to make the thrust washer out of the same od of the current thrust washer and should we be thinking of putting oil flutes in them ?

Excellent....

Now, Dave, are there any other polyimides that might not be the "ultimate" but could suit are needs and not be so brittle ??? I guess part of the cost is it seems to be carbon fibre reinforced PTFE and what's the point of carbon fibre "bling" if you can't see it. Some of the other polyimides are GRP re-inforced - possibilities ???

And, Paul, excellent idea about the additional steeel washer/plate - maybe little to no machining required.

Schrödinger's cat - so which one am I ???

Edited by Rod S on 10th Oct, 2008.

Schrödinger's cat - so which one am I ???

sorry to go a bit off topic, but could you use this Vespel for crank thrust bearings?

Edited by Jimster on 10th Oct, 2008.

Team www.sheepspeed.com Racing

Schrödinger's cat - so which one am I ???

Rod you spot on just went on to duepont's websight and donloaded there product spec sheit they are ranting about the fact you do not need to lub it and that that makes it better for clean inviroment !!

Jim I see no reason why this would not work as a crank trust

My understanding of what TD wrote above is that the thrust washers do not see much of a load until the journal bearings fail.

The axial forces on the idler centreline are more or less cancelled out by the driver and driven gears. However, there is large resultant force due to the couple of the opposing forces that creates a large radial load on the journal bearings.

I believe that the factory recognised this problem, hence the increase in the journal diameter and use of the Torrington bearings.

Once the journal bearings allow the idler to tip, the thrusts start taking the load and subsequently fail in a far more visible fashion than the journal bearings.

Hence, I feel that unless we address the journal bearing issues, then thrusts in fancy materials will have limited benefit.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

http://docs-europe.electrocomponents.com/w...66b800a268a.pdf
here is another link to a little more information

Paul that is close to what I have come to understand but the way I seen it was that becaus the trust starts to fail masive load is put on the the roller bearing which in turn starts to fail alowing the gear to tip which then fails the thrust
so in basic terms we need to work out where the failure starts, is it
A: at the thrust ??
B: at the roller bearings ??

Edited by PaulH on 10th Oct, 2008.

Edited by Rod S on 10th Oct, 2008.

Schrödinger's cat - so which one am I ???

The needle rollers do not need to fail before the load is transfered to the thrusts.

A few thou wear on the needle rollers would be enough to allow the idler to tip and transfer loads to the thrusts.

The idler gear is made of case hardened steel. That includes the journals. The needles themselves will be pretty hard but the case they run in seems to be of a much softer material.

Why did the factory uprate the journals and not the thrusts?

If the journals are in good condition with little wear, there is not enough load on the thrusts to damage them.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

If you look at that failure in the other thread, there is damage to the outer edge of the thrust face on the gear. My guess is that is due to the tipping. The damage would be more uniform if the journals were holding the gear in place.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."