Crank pin re fixing

[Ian RParticipant @ianr]

I have an issue with timing of a 2 6 0 loco using Walschaerts gear.

The crank pin in the middle driving wheel is loose and moves. This crank provides the motion to open and close the valves on top of the steam chest.

I need to remove and refit this pin I hope to use Loctite 638 to secure the pin. I am unable to remove the pin from the wheel.

Can anyone suggest how I can extract the pin ?  What method of pulling it from the wheel ?

[cogdobblerParticipant @cogdobbler]

<p style=”text-align: left;”>Depends on how it was originally secured. Is there a dowel pin or similar that is retaining it despite the main crankpin’s looseness? Or grub screw or “Dutch key” drilled and tapped in from the end? Careful cleaning and inspection may reveal something along these lines.</p>
If all else fails, there is “wick-in” Loctite that is designed to creep into loose fits by capillary action without dismantling. It works well if you clean the job thoroughly with a non-residual solvent such as brake cleaner then Loctite primer etc.

 

[Nigel Graham 2Participant @nigelgraham2]

A possible clue would be the crank-pin being loose enough to rotate and/or move axially but only by a very small distance before meeting a stop.

To me, that would suggest a dowel or “Dutch key” that is tight in one component but not the other.

[Ian RParticipant @ianr]

There is no dowel or Dutch Key its a push fit and you can rotate it 90 degrees. I would like to remove from wheel and re glue. suggestions on how to pull crank pin out please.

[BazyleParticipant @bazyle]

If the rear is accessible can it be punched from the back?
What is there to grip? If there is a thread on it, either internal or external, a small tube of the right length to fit over it then a washer and nut to use the screw to apply the force. This also helps in that the tube protects the cast iron of the wheel being pulled out.

[Michael GilliganParticipant @michaelgilligan61133]

If it was originally “Loctited” in place then, despite the failure, you may have difficulty removing it unless the residue is burned to ash.

I would suggest use of a needle-point gas flame

MichaelG.

[cogdobblerParticipant @cogdobbler]

Hold the crankpin in the vice with soft jaws and work the wheel back and forth until the Loctite residue let’s go.

Or knock it out with a drift if it’s not a blind hole.

[duncan webster 1Participant @duncanwebster1]

If the wheels were loctited to the axle then using heat could destroy that bond as well, resulting in loss of quartering, creating another problem. You could make up a pusher, two bits of say 25*12 with say 10mm holes each end, a short pusher in the middle of one and a hollow threaded pusher to go over the crankpin in the other

[BazyleParticipant @bazyle]

Which loco design is this? If it was serialised the build articles might throw some light on the suggested fixing methods. What state of disassembly is it in to indicate what level of access is available?
Also isn’t the valve normally operated from a return crank? If the issue is that rotation of the pin upsetting the timing relationship of the return crank and the actual pin is remaining true then the required solution is to fix that rotation rather than complete removal. For that a Dutch Key or other method can be fitted.

[duncan webster 1Participant @duncanwebster1]

Original post says crankpin is loose

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