taper pins

[chameleonrob]

does anyone know how to remove taper pins from a 5" gauge masie that are on the crossheads, I've a loco to repair and can't get them out to repack the graphite yarn packing in the cylinders.
rob

[waggy]

Chameleonrob,

You could try playing a flame on the piston rod and the socket of the crosshead, might just expand the parts enough to release the grip of the pin. Try not to heat the pin as that will expand aswell as the rest.
Once you get them out I suggest you drill through and used roll pins in place of the tapers. They are fairly easily knocked out when required.
Another suggestion - not sure what form the gland seals take but you could try rolling PTFE tape into a string and wrapping it around the piston rod, taking the place of the yarn? It does work, see previous threads on here. Save you taking it to bits!

Good luck,

Waggy.

[Shawki Shlemon]

I stand corrected the idea of taper pins is that they completely fill the hole and eliminate movement and easy to remove ,a tap on the small end should do the job provided the body is supported . If there is no room for this then place a spacer around the large end and use multi grip to compress the small end and the spacer together , this should do the job . It may require some force to do it .

[DaveD.]

Hi Folks

Taper Pins

Having had to fit and remove umpty zillions of these things working on teleprinters, adding machines, accounting machines, tabulators and the like, I feel I have a modest fund of experience to impart.

The small end of the pin should be slightly recessed, the large end slightly proud of the collar or whatever. Thus it is obvious which end to smite during removal. With the slow taper, only a couple of thou' of axial movement will release the pin.

If the thing is fitted in the manner of a casually aimed packing case nail, unless the first attempt is true then the pin will bend and you are in the S H 1 etc.

A couple of years ago I had one like that, I was able to slice the excess off with a Dremel tool and get away with it.

You need a good parallel punch, some of the punches now are absolutely dire, soft and too long. I make my own with silver steel in a thin brass holder, not hardened, just flat ended and no longer than necesssary. Usually 3/8" of steel protruding is more then enough.

If you ever get a good punch, I have some by 'Proto' USA, the end is concave, bit like a rivetting punch, to reduce the tendency to slip off.

I feel for you, I've had some awful antics in the past with taper pins, best of luck !!

Waggy is right, when you get it out, shove a Roll Pin in.

Regards DaveD.

[freddo]

If the taper pin is that good a fit and a little imagination, heat and shock therapy won't move them, leave them alone.

As for roll pins - the ME fudge factor - useless for anything that will induce a shearing force across the roll pin - ie in a crosshead - only thing I ever use roll pins for is into a hole bored between the wheel and the axle to prevent rotational slip.

Heat and a goodly wallop is undoubtedly the best way to remove old taper pins as long as you've identified the tapered end - before heating, grind off the small end flush with the crosshead with a dremel or such and use the above suggested punch, then you won't have the problem of a bent or belled small end.

If you can't get them out, take off the cylinders and pack that way, or even remove the con-rod and pull the crosshead out of the slide bars - lots of ways to skin cats and pack cylinders!

[chris vine]

If you are still having difficulty, try to put some extra mass on the crosshead at the thick end of the pin. A tube which just fits over the pin and either quite a long tube or set into a biggish lump of metal.

The increase in mass will increase the shock load on the pin when you hit it because the crosshead cannot spring away so easily.

By now the small end of the pin may have spread a little making things even more difficult!!

C

[chameleonrob]

got them out by drilling though them in the end. they had been put in good and proper, the large end had been peened over, I couldn't really get at the back 'cos the frames were in the way so I was hitting at an angle. taking the cylinders off was considered but would have meant boiler removal due to the design. thanks for the suggestions everyone. all I need to do now is re cut the taper the next size up when I refit the pistons and make so ptfe rings for it.

rob