A Material Question

[david griner]

Hello Everyone,

Need a bit of help here....................have searched the "net" in vain to find an outfit that offers 1/2" round bar, bronze filled Teflon (PTFE).

Per chance, does anyone know of a place selling the bar in less than pallet loads??

Thank you for any help.

Respectfully,

Dave Griner

[Builder01]

Where is it specified that you need this type of material?

David

[Bill Shields]

depending on how much you need, you might try these folks and order a 'sample'

https://www.professionalplastics.com/TEFLONBRONZEFILLED

bronze PTFE is great stuff...been using it for years

[Builder01]

Thanks for the link Bill. Interesting material. Where might you use this in a locomotive?

David

[Bill Shields]

my use was industrial, not loco related.

bronze ptfe makes a very good piston ring material for oil-less reciprocating air compressors...used them in the crude oil business in the middle east. Williams & James air compressors comes to mind (a UK company).

We had the rings made by KAYDON in Baltimore...but as you say they were purchasing it by the railroad car load. I still have some around in the basement (after 30 years out of the business)...but it is 3/4" cross section by about 8" diameter piston rings. It was an odd-ball application but in locations where you have a lot of friction / load and need to get the heat out and DON'T want the stuff to creep...

the only place you might consider using it on a loco is main rod small end bearing (which takes a pounding) and / or tender wheel bearings...but in reality DELRIN AF or moly filled nylon work very well for the rods and basic bronze is just fine on the tender (and other bearings).

since it is so tough to find..other materials are much more practical to use.

[Builder01]

Interesting, thanks Bill. The original poster has not responded and I wanted to make sure it was not something I needed too! By your description, as you say, there are probably other materials for miniature locos that will work just as well.

David

[david griner]

Gentlemen,
Thank you for your interest and reply's.

The intended purpose is to be used for the reversing valve in a Westinghouse 11.5" air compressor being built in 2.5" scale.

The reversing valve slides in a bore and feel that in order to get the best sealing surface, the PTFE will adjust to the specific bore more readily that a metallic material. Machining the valve is quite exacting so am hoping the slight "give" from the PTFE will allow good seating along with good wearing characteristics.

Again thank you all for your interest and input.

Dave

[Bill Shields]

I would go with glass filled PTFE -> much easier to get and for that application, will be just fine.

[Chris Hollands]

Try a seal company that makes/sells hydraulic seals , we used these seals in hydraulic cylinders mainly and a few other applications some places will make the seals to suit or if what you have is a common size then make your item to suit the seal .
We use to put them in boiling water and then use a hose clamp or similar to squeeze them back to shape and size once you stretched over the piston or what ever you were putting them on .