Slide way seizure repair

[Mark TyldesleyParticipant @marktyldesley75376]

Hi All,

The cross head in my 3" scale traction engine seized in the slide way,after a very short period after increasing throttle, and was forced to drop the fire.

After freeing the cross head I soon found out the bottom slide way was scored and fairly rough along its length, (I will point out the slide was well lubricated) prior to seizure, and totally unexpected

what I'd like to know is there away to salvage a scored rough slide way to give agood running surface

your advice very much welcome

Mark

[Mark TyldesleyParticipant @marktyldesley75376]

[Boiler BriParticipant @boilerbri]

Hi can you put some pictures up please

Bri

[Paul LousickParticipant @paullousick59116]

You can machine the entire surface and bolt a plate over the slide area with countersunk screws. Use a gasket sealant between the plate and the steam chest.

[Mark TyldesleyParticipant @marktyldesley75376]

Hi,

thank you for your suggestions, the plate idea seems good, my initial thoughts are, could I milling the surface afew thou, and just pack up the slide? As there's packing already in place, and what would be the best method to polish surface, and would I have to harden the surface ?

mark

[Mark TyldesleyParticipant @marktyldesley75376]

Hi,

thank you for your suggestions, the plate idea seems good, what material would you suggest for plate?my initial thoughts are, could I milling the surface afew thou, and just pack up the slide? As there's packing already in place, and what would be the best method to polish surface, and would I have to harden the surface ?

mark

Edited By Mark Tyldesley on 30/09/2014 07:45:30

[JasonBModerator @jasonb]

Was either the slide bar or cross head case hardened? This should have stopped it picking up and will affect how you go about the repair.

I'd remove the slidebar, anneal if it was case hardened, machine or draw file the damaged surface depending on how deep it goes, reharden and fit. Then make up a bronze slipper from shim to fit the underside of the crosshead to make up for the material removed from the bar. I'm assuming your engine is steel on steel, if it does already have slippers then just use shim to pack out the lower slipper.

J

[Mark TyldesleyParticipant @marktyldesley75376]

J

i think it's metal on metal just I'm trying to fathom out how to remove crosshead from piston rod, there's a small metal projection each side of crosshead I'm thinking that maybe a locking bar of sorts but unsure how to remove it to remove rod

mark

[Mark TyldesleyParticipant @marktyldesley75376]

No idea if it was case hardened

[Mark TyldesleyParticipant @marktyldesley75376]

Hi

well this morning after another look at slides iv noticed the top slide is also in a bad way, so question is if I was to replace both totally from scratch what metal should I use, gauge plate?, and should it be case hardened after machining, and how should I go about case hardening, as iv never undertaken the process before

mark

[JasonBModerator @jasonb]

What engine is it.

You really need to find out if the cross head has had any form of hardening as only one surface needs treating. Are there any signs that the crossheas has also picked up? try a needle file on teh rubbing surface, if it skids then its liekly to be harder.

Assuming neither have been hardened then the bars can be replaced with mild steel and they should not be too difficult to case harden.

The crosshead is likely held by a round or oval tapered pin

[Mark TyldesleyParticipant @marktyldesley75376]

Hi Jason,

the engine in question is a Plastow 3" Burrell still havnt worked out if crosshead or slides have been cased as yet

[Mark TyldesleyParticipant @marktyldesley75376]

Hi

just to update you I have dismantled the slide way and managed to salvage the slides some rubbing on surface plate ect, the crosshead I can't repair at moment as I will have to mill afew thou to clean surface, neither items where case hardened so I will be doing that later, is it worth hardening crosshead and slides or just crosshead? Your thoughts welcome

mark

[Neil WyattModerator @neilwyatt]

What about Jason's suggestion of fitting bronze 'slippers'?

Neil

[JasonBModerator @jasonb]

If you are going to have to machine the cross head then it will be quite easy to fit slippers. The easiest way would be to mill away a bit more thickness than needed, soft solder on some bronze and then machine that back to your required thickness.

A bit more tricky is to make separate slippers which fit into teh gap between slide and crosshead and have a recess in the back so they don't slip out, if they wear then a bit of shim behind them will take up any play. You can just see the bronze slippers on my fowler in these shots

Doing it with slippers will save having to worry about case hardening, the small area of steel crosshead that contacts the sides of the slide bars is not worth worrying about.

Out of interest what type of oil were you using?

[Mark TyldesleyParticipant @marktyldesley75376]

Hi Jason

thank you for the information, the slippers do seem a good option, iv been reading up on installing them, via a peg sweated into shoe then a press fit into crosshead, I'm still debating on which option to take, having looked at the crosshead there's not a lot of meat left to fit slippers, so I may play safe n case harden, this engine was built in mid 80's and lasted till now without slippers! But, I will make up anew crosshead as a practice piece and attempt to install slippers! As I havnt touched a lathe in years, and with anew lathe n milling machine due next week! I'm going to need all the practice and advice I can gather!

So if I go down case harden route do I do slide n crosshead togeather? And the oil it was running on was LBO 460

just out of intreast what thickness are your slippers? And any chance of seeing this recess if possible ?

cheers

mark

Edited By Mark Tyldesley on 01/10/2014 17:57:47

[JasonBModerator @jasonb]

3/64" this should show them, click the image to make it bigger

[Mark TyldesleyParticipant @marktyldesley75376]

Hi Jason

many thanks for diagram, looks an easy item to make up, I shall give it ago, it mentions gunmetal but brass will be the option togo for, may make them alittle thicker to

cheers

mark

[JasonBModerator @jasonb]

Brass is not the best bearing surface use bronze or GM. The easiest way to get it would be to buy suitably sized round stock and saw it lengthways down the middle then machine your rectangular section from that.

J

[Mark TyldesleyParticipant @marktyldesley75376]

Hi Jason

yes bronze my mistake, why do you mention round stock ? Is that the best way to obtain bronze or Gm?

mark

[Mark TyldesleyParticipant @marktyldesley75376]

Jason

whats the best way to mill out that recess, been thin how do you hold it down to milling table, read you can use double sided tape, be interested to know how you did it

cheers

mark

[JasonBModerator @jasonb]

You can buy gunmetal in square bar but its hard to find, so cutting from round is often easier if the part is not too large. Bronze block is available but again easier to come by round.

Machine the sliding face and then soft solder to something that you can hold in the vice, mill the recess, melt the solder and rub on some wet n dry to remove solder.

J

[Mark TyldesleyParticipant @marktyldesley75376]

Cheers Jason thanks for your help much appreciated

mark

[Ian S CParticipant @iansc]

If at some time you need a steel on steel bearing, one component should be hardened/case hardened, by doing this the two parts are in a different state, remember that in most cases you should not run two surfaces of like metal together as a bearing, the exception is cast iron.

The slippers could be made of cast iron.

Ian S C

[Mark TyldesleyParticipant @marktyldesley75376]

Hi

I have been looking into fitting slipper, I can just about fit them with some adjustment, but critically what Is the minimum thickness that I can get away with? As there's very little metal to mill out of crosshead

mark

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