I was wondering what the state of the art is for pins and bushes (motion, suspension and brake)
Traditionally it was ingot iron case-hardened 1/16 inch.

These days there are lots of specialised steels and composites about. So who's using what?

I've heard of pins made of high tensile steel being used unhardened - is that reasonable for things like equalising beam pins where the load is so high, and lubrication so unreliable. Do wear resistance and tensile strength go hand-in-hand, or is hardening necessary?

SAE 1026 works nice with a deep case hardening for pins & bushings.

frisco1522@sbcglobal.net

Different applications require different techniques and materials. I find it useful to use softer materials for either the pin or bushing so I can control which part gets worn and replaced.

Beware of using a harder bushing than the material it is installed in - it isn't uncommon to have a hard bushing open up the hole in a softer rod, for example, which then leads to the need for remachining the rod end rather than just replacing the bushing.

If you are rebuilding the spring rigging, it is possible to include grease fittings to lubricate the pins and bushings in the process.Or,perhaps some self lubricating materials can be used.

Best wishes and don't be afraid to experiment.

dave

irondave@bellsouth.net

For bushings, 1026 DOM tubing can sometimes be used to great advantage. For pins 1045 works well. Both steels caseharden nicely, leaving a softer core. If hardness is to great I've seen heads of pins break off, but not seen a pin break in half. When making bushings, inquire at the heat treaters to determine how they will harden the material, if it is going to be quenched extra stock may be necassaary. The bushings can sometimes distort.

HMSC
HISTMACHRY@AOL.COM

> I was wondering what the state of the art is
> for pins and bushes (motion, suspension and
> brake)
> Traditionally it was ingot iron
> case-hardened 1/16 inch.

> These days there are lots of specialised
> steels and composites about. So who's using
> what?

> I've heard of pins made of high tensile
> steel being used unhardened - is that
> reasonable for things like equalising beam
> pins where the load is so high, and
> lubrication so unreliable. Do wear
> resistance and tensile strength go
> hand-in-hand, or is hardening necessary?
Ex-Cell-o Brake pins are induction hardened SAE-1050. Ex-Cell-o ground and polished pins are also induction hardened high grade high carbon steel, which have been used as spring rigging since pins before I came here.
We have used 8620 or 8620 calcium treated for case hardened pins and bushings.
Cold drawn 1020 ,case hardened, was used in the lead truck swing link pins of #2.
1117, 4140 hardened and drawn back to Rc 56-62.
For pins that aren't drawn back we'll use cold drawn "stressproof" or the more expensive ground and polished "stessproof" when sizing dictates.



jhewlett@co.genesee.mi.us

Thanks folks,
Useful info here.
My real question remains however - does anyone use as-machined, unhardened pins and bushes? and if so, what material?

> Thanks folks,
> Useful info here.
> My real question remains however - does
> anyone use as-machined, unhardened pins and
> bushes? and if so, what material?

We have successfully used 4140/42/45/50 furnished in up to 320 brinell depending the availability from suppliers. Combined with mild steel or bronze bushings service life is reasonable.

Typically we prefer case hardened bushings and slightly softer case hardened pins (8620). We lubricate once per year with graphite and grease when pins are removed for inspection. We have found no benefit to providing a way to lubricate equalizing pins using oil holes or grease fittings.

Strasburg Rail Road
linnwm@supernet.com