Garden Railway Forum

Hi folks, my reverser on my internally fired mamod has been leaking a little ive tightened it with my fingers as est i can and put steam oi down it and it can now run at a steady 18psi without loosing pressure but i really need to add a washer, add a new spring or try tightening it with a proper spanner for it (something i dont have yet) anyway heres a video after id tightened it up as best i could:
https://www.youtube.com/watch?v=XW4F60oQLe4

A good thing to do is dismantle and lap/cross hatch the faces together clean add steam oil to faces and reassemble.
(Cross hatch/lap let us know if you need help on this process if needed)

yeah advice on Cross hatch/lap would be appriciated
thanks
Joe

Put some wet and dry on a sheet of glass or a known flat surface making sure it is all flat. Add some oil and gently rub flat the face. Start coarse then go fine with the wet and dry.( Lapping faces in) As a finish go medium and rub say twice one way then 45 degrees the other on both faces as a finish. This will give the steam oil somewhere to grip and allow mating to take place (Cross hatching)

The aim is to first flatten the surfaces then add a cross hatch pattern to hold the new oil. Wash the reverser to degrease and clean off all the brass dust.

Reassemble with clean thick steam oil. As you use they will mate for life. Sealing better. Make sure you tighten up the centre bolt with the spring and washer.

ok thanks for info

You know the pistons get sided?
The faces do too. Never interchange the oscillating faces.

Going back to pistons, when taking the rod off the wheel don't rotate them. I marked the brass hole connection at the end of the rod (outside part, small mark with scribe) in case I removed the con rod from the wheel spoke to oil etc.

Run the loco in too. About 20 goes should see it smooooth out. All helps and is what makes it interesting.

https://www.youtube.com/watch?v=yTCnpazV0Uc

Look how slow and smooth they can get! Keep going it's all worth it in the end.

The reverser valve pivot bolt has a 6BA head. I use a 6BA ring spanner, but a simple mod that many apply is to cut a screwdriver slot into the head.

These valves were only designed for less than 1 Bar/15 PSI operation, so the usual mod for increased boiler pressures is to either add a 2nd spring or add some sort of spacer onto the bolt so the spring is being compressed more. Also ensure that the reverser valve pivot bolt is free to rotate and is not being interfered with by the steam & exhaust pipes or the cylinder pivot bolts.

Chris Cairns

thanks chris thats very helpful i will try adding a washer to start with

Apropos of nothing, this reminds me of the story told of HMS Victory. The Admiral had his washerwoman come aboard to do his personal washing, and it was the responsibly of the deck officer to send a flag signal ashore for a boat to come and take her off the ship when she had done. One day, he got the signal wrong, and sent "Please send boat for the Admiral's Woman." Realising his mistake almost immediately, he sent the following: "Correction - Please insert washer between Admiral and woman!"