Gib keys. How can they get so stuck?

[Scott]

Hello all.
I've encountered my first stuck gib key.
Hooly dooly they test your patience don't they?

The story is I've decided to do what I thought was another quick spruce up of a lister D I've had for awhile. I've had it about a year and it was in fact the first engine I got.
I have not been in this hobby for very long at all have I.
Anyway it is a really good runner but has been painted before and looked very tired as paint was peeling off and lifting badly.
She is not on a trolley and has not got a dedicated cooling tank so I thought now was a good time to get everything done.
I also thought it would be a good chance to check everything inside like bearings etc and to give her a good inside cleanup.
So I got her out and gave her a good run to make sure she still ran well and then started stripping her down after she cooled down.
I thought I'd better start by taking off all the stuff that can easily break.
I started stripping the carby and stuff like that off. And then the magneto (remembering what my old mate Arthur always said...mark the timing....and double mark the timing and make sure you know what the timing is and don't forget the timing)
Then the flywheel. I looked at the gib key and suddenly remembered stories from hell.
I started thinking about this job about 6 months ago. I turned the crank so the keyway is at the top and sprayed magic spray in there and left it soaking since then so I thought it would be fairly free.
Wrong.
I tried a few times with steel wedges. No good. I quickly gave up on this idea as I can see more damage been done to the key and flywheel.
So I heated the flywheel up to see if that will make a difference. Wrong.
So I thought I'd better make a decent puller.
The puller worked really well. I pulled the head straight off the key without any drama's at all. It's amasing how much force 3 fine thread 12mm bolts can exert. I also bent the 8mm plate I used to make the puller out of. I should have been paying closer attention but it's too late now.
So out came the welder. Welded a rod to the key no worries and used a slide hammer.
I thought the heat would shake things about a bit.
That just pulled a bit more off the key. At least my weld did not break I suppose.
Now I'm starting to worry.
So today I'll reweld the rod on and try and tap each way. That is tap in and out to try and break the grip the gib key has onto with the rest of the engine.
Failing that I'm thinking about drilling a 3/16 (or bigger if I can but it'll depend on how accurate I can get a pilot hole through there without damaging anything) hole through it and trying to use the press to get the flywheel off. I'm thinking the key will collapse with the force of the press. Is this a good idea??
How else can I try to get the key out?

At least I get plenty of time to make the wheels and other stuff up while I wait for the welds and other hot stuff to cool down before another failed attempt to remove the key.

Cheers then
Scott

[oceans15]

example of a transport for a light to medium weight machine.

[oceans15]

If the 'D' is/was a really good runner, why take the flywheel off?? Maybe just clean it, paint it and leave it assembled and running. From experience it is better to put your effort into building a transport with a turntable - worth the extra effort i reckon - You will have to drill out that gib key if you still want the flywheel off - cheers

[Scott]

If the 'D' is/was a really good runner, why take the flywheel off??

I'm very sorry to say I'm a bit of a perfectionist and it has to come apart for me to paint it and detail it otherwise I would have left it in the state it was.
And I want to check the bearings.

The transport is the easy thing to build I reckon

So I rewelded the rod onto the key and the key broke at the flywheel this time.
I've drilled it and, hopefully, I'll put it in the press after I've cleaned up the crank later today.

Cheers Scott.

[oceans15]

Don't get me wrong - I hope you do get that flywheel off by beer o'clock today - just making the point re thinking long and hard about fixing something which isn't broken! I almost did the same thing a few weeks ago but decided at the last minute to leave the flywheel on a CF diesel i wanted to paint which runs perfectly - I washed it down with dynamo and hot water, rinsed it off and sanded it. Then good wipe down with prepwash wax and grease remover. I painted behind the flywheel first while turning it then painted the rest - forgot to say earlier that heating cast iron parts is not recommended either - cheers - Chris.

[Thomas Tisch]

Hi there,

I gathered some experiences over the years with stuck keys in Bulldog tractors. They are probably stuck because they didn´t fit properly to start with and were belted in by force to get them tight. Talking to an old bloke working at the LANZ factory at the time, he told me that the keys were actually blued in.
Now, how to get them out. I used to drill some out which is a pain ***. Chances are you don´t drill straight. In the worst case you damage the shaft or the flywheel. After drilling you still need a very strong puller arrangement to pull the whole lot off and collapse the key.
A much better and easier way is to solidly weld the key onto the flywheel and then pull the whole assembly off. The key welded to the flywheel cant "slip ìnto" the flywheel when pulling it off. If you were to pull it off without the weld you would pull the flywheel onto the key and eventually crack the hub. The keys on the Bulldog at least are tapered at 1:100.
Now, after you have got the thing off you just tap the key off the flywheel. The weld to the cast iron flywheel is weak and breaks easy leaving just a little mark. That damage is nothing compared to a drilling damage.
By the way, to pull a Bulldog flywheel off in that way you need at least a 10ton jack and brackets to handle that.

Good luck,

Thomas Tisch

[Scott]

Hello all.
It's done, didly done.

A lot of heat on cast isn't good but the heat from a primus torch isn't a lot of heat. I think it actually allowed some magic juice to be pulled into the joint.

So I drilled the key and then took the flywheel and crank around to my mates place where I cleaned up the shaft so there was nothing for the flywheel to bind up on and chucked it in the press.
A bit of pressure and then BANG. The grip the key hold on the flywheel let go.
So flywheel off and new key needed.

I'm glad I took it all apart. I noticed a bit of an oil leak from the crank seal so a new one can go in now.
And I need to find a new gib key.
Do Gib keys have a slot on the top of them?
In the picture you'll see the puller I made and the key after removal.
I drilled the hole really straight and bang in the middle of the key by the looks and you'll notice a slight groove, or recess, where the top of my hole is.
There is not a mark on the flywheel or crank.
On the puller you can see 2 sets of holes.
The outside holes were so I could use a bigger puller and pull from the centre of the crank. But I forgot the guy across the road has not brought my puller back yet so that necessitated more holes closer in so I could push against the flywheel.

The key was really, really clean when I pulled it out. Someone must have been very energetic when they flogged it in.


Cheers Scott

[oceans15]

Well done Scott - those keys are a challenge for any restorer when they have seen many years and seasons outside. My father and I spent almost 30 hours removing a 24" cast iron pulley from a shaft with no damage and no heat. I was determined to save it due to the reduction it gives when driven by a 4" pulley. We just kept breaking then strengthening the puller we made till it had the pulley off. Cheers - Chris

[tanksmate]

Hi All,  just a further note to that by Thomas Tisch above, where he mentioned that the Lanz  factory fitted Key's  by "Blueing-In" , I could not help to think, I wonder if Scott knows what this means, " Bleuing-in"  I am an old Plumber ,so it may be better that someone like Jopeter or Ian (rustyengines) explain just how this is done. I have used Blueing to fimd high spots, but not to actually fit a flywheel.  cheers all   John

[Scott]

Hi All,  just a further note to that by Thomas Tisch above, where he mentioned that the Lanz  factory fitted Key's  by "Blueing-In" , I could not help to think, I wonder if Scott knows what this means, " Bleuing-in" cheers all   John

Hello there John.
Well said and a procedure probably many would not about.
Yes. I'm one of the unfortunates who have had to use 'Bearing Blue', or more correctly Prussian Blue, during the course of their trade.
I'm an electrical fitter/mechanic by trade and we had to use it quite a bit with gear alignments etc.

It might be a good thread for someone a little more literate then me to write down some procedures in it's use.
If I wrote it all I would say is smear it on, insert, withdraw and file off the high spots (less blue spots) until the (in this instance) the key could be withdrawn and the colouring is uniform along all sides and length of the key.

Something else we used a lot of was flexi-gauge. The stuff was brilliant for determining clearances. Can you still buy it?

Cheers then
Scott

[Killer]

I was told by some old blokes (even older than me) years ago that they used to fit flywheel gib keys soaked in a very salty brine paste to encorage corrosion and the key would 'grow ' tight once in place and never walk it's way out.

After some of the experiences I have had with gib keys I tend to believe this!

But I have also seen some ill fitted keys that came loose every time you turned your back on them, bluing is a good way to fit up a key correctly.

Cheers John.

[rustyengines]

Gib Head Keys
I have been trying to find the best way to explain a Gib Key
How they work is the locking of two tapers which MUST be a perfect fit
The taper on the key is 1 in a 100, 1 mm difference in size in every 100 mm in length
The other part flywheel etc, is the same taper
‘Blueing-In’ This is a process where the taper surface is ‘Blued’ and it used to be 'Bearing Blue', or ‘Prussian Blue’ this disappeared when felt making pens appeared and the colour does not matter it is just that ‘blue’ is an easier colour to see
You blue the top surface of the key and fit into the into is position with one firm tap, then remove the key and what will show up on the key is spots where the blue has been removed, this is the high spots and you lightly file the high spots, blue the key again and refit. Kept doing this until the blue is removed from the whole top of the key this now means the taper on the key matches the other half
Do not assemble a key ‘Dry’ oil the key it will not make it lose, it will allow the key to go in further and be tighter a ‘dry’ key might start to bind and not go all the way in
If the tapers are correct you ‘do not’ need the belt the key in, two or three good firm taps with a normal size hammer and the tapers will lock and the key will not come out
very salty brine paste to encourage corrosion
No way would you do this as you could never remove the key, all the jobs where I have used Jib Keys was always done so they could be removed. The biggest Gib Key I have done was 300mm long 30mm wide 25mm thick and held on a blower fan about 4 metres diameter and weight about 6 tonnes
If you look at all the old machinery of any size there is Gib keys everywhere with nothing else holding on the flywheels, gears, pulleys etc  just the Gib Key
They do work very well if fitted correctly
I have look at a number of web sites and could not find one that told you everything you would like to know, there is most likely one but where?
http://collections.infocollections.org/ukedu/en/d/Jgtz122be/8.html
Ian

[Combustor]

      If first attempts with wedges or simple pullers don't succeed, it is often easiest to resort to drilling at this point while the key has its head and the flywheel has not been pulled on even tighter. You need to make a drilling guide, assuming there is some extra keyway length on the shaft. Find a piece of key about the same dimensions as the one that is stuck, say 50 mm long is enough, and also find a mate with a lathe who can locate the centre of the key and bore the length of it to a drill size half or two thirds the key thickness. Clamp this guide in the keyway and drill right through the stuck key.(You may need to buy or make a longer drill or 2). Discard the guide, then take a drill on or just under the key thickness and drill to final size. Be sure the shaft is clean and free of burrs. A wedge should move it easily now.
     If the flywheel is still a bit tight on the shaft, spray some lube down the keyway and then crank the engine over and let it fite several times, stop it and check for movement. Do this as needed till you get some movement and you should be able to work the wheel off.
      Hope this helps, worked well for me.  Regards,  Combustor.

[rustyengines]

Gib Key puller
Here is one way to remove a gib key
http://www.oldengine.org/members/evans/gibpull/index.htm
http://www.oldengine.org/members/evans/gibpull/page2.htm
Ian