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C4 will remove them but use it sparingly.

Not afraid to call out the heavy artillery, eh Mark?

:-)

Ryan

Kelly, might I suggest;

1) A custom hydraulic rig with some cheap bottle jacks pressing the hind end of the bushing (with a round torch cut plate) against the front of the cylinder casting. Some kind of yoke, 3 or 6 points against a steel support ring on the front of the casting to spread the load ? Might need a “porta power” unit to route the hose into the jack, or put the jack in front of the “puller” and connect it to the rear end of the bushing with some long threaded rods (1” maybe).

2) Using an abrasive cutoff wheel (maybe a dozen or so) to cut a grove through the bushing and relieve the pressure. You might be able to rig up some “depth of cut” guides to mount alongside the abrasive wheels to limit the depth of cut to the bushing thickness. Watch out for binding on those last few inches !!

3) Really exotic here, rig up some pipes in close contact with the bushing and pump liquid nitrogen through them. Once it shrinks by 10 thousands or so just pull it out. Probably too NASA like, but I bet you could pull the bushing out with one hand ! That's how they put valve seats into new car engines, with a robot of course.

I’m sure I’ve seen option #1 in some old photos to pull bushings into place, should work to get them out. But there is a lot of stuck stuff between old shafts/bushings and bores, lots of friction there. I’ve drilled straight through old 1" shafts and split them sideways with a hacksaw blade to get each half out of a really stuck bore. This was after I tried pressing them out with enough force that I was sure it would break the casting any minute.

Cheers, Kevin.

It takes time....but you can bore out the bushings with a portable bar until they are thin enough to remove like a tube end. This probably reduces the possibility of damaging the valve chest more than any other means I'm aware of. I like the thermal idea, though....if you heat up the casting then cool the bushing it might work.

dave

I have (in PA) a sales brochure for enerpac type equipment built for steam locomotive work. Honestly, I never would have guessed anything so modern would have been around back then but..... Regardless, in the literature the rig (consisting of a hollow piston hydraulic cylinder) is shown both installing AND removing valve bushings with the accompanying rig. Very simplistic, sure you can visualize as there is really no other way to do it with a hollow bore cylinder.
See remarks regarding idea 3.



I have used wheels to remove Iron bushings before, time consuming and messy (lots of grinding dust) but ultimately effective.



The thermal conductivity between the two components (assuming a proper interference fit almost definately prevents the bushing from being shrunk to the point where it could just pull out. But..... one additional thought which would likely work quite well, had planned on using it next I need to attack a bushing. Give a call, I'll go over it with you.

All that having been said, Air-Arcing is by far the way to go! Fast, easy, cheap and effective! Unless one can't make a mess in the valve chest (if it is desired to leave the pistons in or something similar)....then option 2 is out as well. In which case, give a call.


Cheers, Jason

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Marvelous. Really not looking forward to hearing the foamers whine about how you changed 31's appearance... or perhaps it's time for 972's day in the sun? ;)

I have removed large pressed in bearing races by arc welding stringer beads on the inside surface of the race parallel to the axis of the shaft. The theory is that the weld bead shrinks a little and takes the race with it. It doesn't have to be a pretty weld or even a good weld; it just has to stick a little. If a couple of beads doesn't do it add some more.

I don't know if this would work with a valve bushing but it might be worth a try especially if the alternative is chisel or air arc.

If you try this could you post the results? Thanks.

Chris

Kelly's post of 0840 hrs today is overwhelming evidence of why he's "cool".

Howard P.
Crater Lake, PA

SP2479 crew removed the left front valve bushing using heavy plate and all-thread. Rear plate was cut to fit at back of cage and reinforced with a piece of 1" x 2" bar stock. A section of rectangular steel tubing was cut to fit between back plate and a section of 1"x2" attached to studs that retain valve cover. This was used to push on rear plate while simultaneously pulling on front plate. All-thread holes were positioned as close to edge of plate as possible. Some machining effort was required, but removal of cage took about an hour. No damage to cage or valve wall.

We may be slow but be get the job done.

I've seen simliar work done, on a smaller scale...removing stuck u-joint caps from drive shafts, by loosening them with a bead of weld on the ID
Jeff

Jason wrote;

"The thermal conductivity between the two components (assuming a proper interference fit almost definately prevents the bushing from being shrunk to the point where it could just pull out."

Well, the surface contact area between the casting ID and the bushing OD is probably about 10% of the bushings total outside surface area. So if you time it right (before the casting can start to cool too much) the bushing will likely just pull out.

Yes a solid bore (Bore ID area = Bushing OD area) with a length several times longer than the OD probably cannot be pulled apart from an interference fit, but you probably couldn't push it together in the first place. Dowel pins are kinda of a special case (Length >> OD) since the OD is small enough that the stresses in the part they are hammered/pressed into are low.

Internal combustion cylinder sleeves are more like a "tight" slip fit than a true interference fit.

Steam engine valve bushings are a special case since you don't want it to rotate.

These "chilling" thermal fits are used in exotic aerospace applications where light weight parts need to be put together without too much force. But it requires special gear and fitting tolerances. The assembly technique is totally reversible if designed correctly.

Cheers, Kevin

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So how does one make new bushings?