replacement of piston O rings on Accucraft Forney

[Janski411]

Hi,
First of all I would like to thank you for welcoming me to your community. My name is Janusz, Polish Canadian, currently living in Ireland (retired).
I would like an advice on changing piston O rings on Accucraft Forney, essentially proper sequence of disassembly. It looks like the side rods pins are pressed to the wheels? I could not find any info on this or any other forums. Any help would be appreciated.

[ge_rik]

Hi Janusz
Welcome to the forum.
I can't help with your enquiry, but I'm sure someone here will have a solution.

Rik

[Keith S]

Hi Janusz.

I am not familiar with your locomotive, but I just did some reading about it and it looks like the engine is based on Accucraft’s “Ruby” design. I don’t have one of those either but have worked on a very similar engine. I read the Ruby assembly manual, and it says the rods are held onto the cranks by little semi-circular spring clips (circlips?) that fit into grooves on the cranks. It looks like the cranks ARE pressed in but you shouldn’t need to remove them.

In fact you shouldn’t even need to remove the rods at all You just need to disconnect the driving rod (the one from the piston rod to the rear driving wheel) from the piston rod at the cross-head. This looks like it’s either another little clip or a bolt that threads into the cross-head. You can let it dangle loose as you loosen the bolts that hold the rear cylinder end cap to the cylinder. Then the piston ought to pop right out the back, along with the cylinder end cap and gland. Alternatively you could remove the front cylinder head and push the piston through but I would be careful doing this so you don’t damage the O- ring in the gland.

When I did this job on my Dad’s similar engine (a Porter) I replaced the O-rings with a material called “Viton” which is heat and oil resistant. I found two Viton rings in a package of assorted size from a plumbing shop. The ones that originally came with the engine were deteriorated. I wonder if that is because we were using Roundhouse steam oil in it after we ran out of the stuff it came with. I don’t know. But the Viton ones work very well Anyway it was an easy job and returned the engine to working order. I hope this helps.

[Janski411]

Hi Keith,
Thanks for the reply. I could not find any info on service on Forney and like yourself looked up info on Ruby. Accucraft changed the design on motion
on Forney. There are no circlips or e-clips, solid flat head pins all around. Crosshead slides on a solid guide and the piston rod is pinned to the crosshead by a tiny blind pin. And the rods are connected by a flat head pins. The piston rod pin sit in an open hole on the wheel and It looks like the only option is to use a small punch to get it out. I will wait and hopefully somebody may offer another solution. Thanks for your effort to help me out.

Janusz

[Keith S]

That does sound inconvenient. Well, good luck!

[Janski411]

Actually, when I first looked at the Forney to determine how to change the O rings, my first thought was: there is no "magic bullet". Anyways, it does not hurt to ask other people's opinion and your suggestions were very helpful. As per my initial assessment, the only way to do it is to is remove the
cylinders, change the O rings and reassemble. Pistons, rods and wheels cannot be removed individually, it's all one assembly. Another project to add to
many others. I may take some pictures and post them if this is acceptable on this forum

[philipy]

I may take some pictures and post them if this is acceptable on this forum

Pictures are always very welcome here. Please do take them as you go along and post them.

[Lonsdaler]

There is a well known Accucraft service agent in Wales called David Mees (Abbeybach Engineering). He would be well worth contacting for advice. He's not on this forum and doesn't seem to have a website, but he and the company are on Facebook, if you have access to it.

[Janski411]

Thanks Phil,
I will contact David for an advise