Retaining Cylinder Liners

[GWRdriver]

Hello All,
I'm not too far away from installing the cylinder liners (centrifugally cast iron) in the cast iron cylinders of my current loco project. My cylinders roughly resemble those for Ken Swan's Bridget, but are not from Bridget. Liners are 41.28mm bore x 45.34mm OD, overall length 85.75mm.

Recently I viewed a Youtube series on the making of a set of cylinders, produced in the UK, and the experienced machinist builder used Loctite, with an ,002" curing space, to retain the liners. I've never heard this spoken of in the USA before and wondered if this has been successful in the UK and elsewhere.

I would say that using the correct Loctite product for the application would be very important, although I gather heat would not be a problem as cylinder temperature would tend to be below the critical Loctite range.

[miken]

Cast iron liners are usually simply pressed in to cast iron cylinders. With steam models it only needs a very slight interference fit. They are never going to move . I've fabricated cylinders from bits of brass and bronze and pushed in iron liners with no problem. Also made an alloy cylinder for full sized motorbike and pushed a liner in with no issues. Why do you want to use loctite?

[simon6200]

I Loctited cast iron steam chest liners into cast iron cylinders. Close sliding fit. With the cylinders, the covers will make sure the liners can’t budge.

[uuu]

I suppose the only restraint required is to stop rotation - so any ports or drains line up.

Wilf

[GWRdriver]

Oct 29, 2024 9:20:46 GMT uuu said:

I suppose the only restraint required is to stop rotation - so any ports or drains line up.

Wilf

Yes, that's certainly a consideration, and if I ended up using Loctite, and rotation was a consideration, I would probably run a weensy setscrew through one end of the cylinder casting, but only far enough to stop rotation, . . . not enough to put any radial pressure on the sleeve.

[simon6200]

If someone can explain what rotational forces are acting on a cylinder I would be obliged. The piston certainly isn’t rotating. I’m pretty sure if a liner was a light push fit, I would not be able to rotate it by any means.

[miken]

So; Now to completeley contradict my own earlier reply!

Here is a link to the building of the full size Brighton Atlantic Locomotive "Beachy Head" showing the cylinder liners being loctited in to place.
Fred Bailey who built it supplied me with many drawings and parts for me to measure when I was building my Brighton "J" class tank engine.
The J and the Atlantic share many common parts including cylinders .
Even so, I still pressed my iron liners in to place.
Although ive just remembered that I pinned the 3 part piston valve liners with a brass pin to make sure they dont move laterally.

www.bluebell-railway.co.uk/bluebell/locos/atlantic/latest_12.html

[andyhigham]

If the steam passages are machined as pockets the cylinder wall then the liner needs to be loctited in to avoid the steam leaking across the ports.
With drilled passages there is no need

[JonL]

I did exactly this, contacted Permabond and told them the issue, the oils, the temperatures, steam and other issues. They even dedicated an engineer to helping me find the correct adhesive. It's been fantastic and I've used it for many applications since. In my case I used it to fit a mehanite sleeve into a porous cylinder casting.

Permabond HM162. It wasn't cheap but I bought the bottle in 2019 and it's like an everlasting gobstopper, still using it now. I cannot recommend it enough. In theory you can even use it on oily surfaces and it ignores the oil. Witchcraft!

[GWRdriver]

Thanks everyone, especially JonL, for all your comments (and a proven product name.)

PS - Product is on it's way.

[GWRdriver]

The Permabond was received and using a 0.0025" curing space the liners shoved in without a hitch.

To answer Miken's question above, I had no way of measuring the cylinder bores for straightness or roundness. Although they were single-point bored on my mill, a lot of clamping and machining has happened to the cylinder castings since that time. I do however have a way of insuring straightness and roundness in the liners, at least to the extent that I'll be concerned about it. So to prevent a deformation in the cylinder bore from affecting the liners, if pressed in, I elected to "float" the liners in on a film of locking agent, with a narrow collar on the gland-ends being a very light press (-0.0005") in the tested round bores, to insure they are correctly located at that end. Slight tic marks located the steam passage cluster alignment and no rotation occurred. Clock gauge testing shows the finished bores to be within 0.001" parallel to the frame in 3.75". I'll take it!

Air tests show everything sealed nicely, but it will be some time before they will have a steam test.