Gear/Pulley Pullers revisited

I didn't want to hijack the post below, but I'm wondering how he's gonna get that pulley back on when the time comes. There's bound to be a seal behind it. I'm in a similar situation - had to pull a gear in order to replace a seal behind it. I got some good advice from good people on this board and from local mechanics about heating the gear in an oven, but what's the heat gonna do to my nice new expensive genuine John Deere seal? One of the local guys said I'd have 30 seconds to get it on the shaft in the correct position and get it cooled off. 30 seconds at 500 degrees is a long time in close quarters. I wondered about making a heat shield out of tin to give me a few more seconds, then cooling the gear with water, but sooner or later, I can see me screwing this up. I'm probably overthinking this. That's one of my major faults.

This is a pic of my homemade grabber that I used to get the gear off.

dont know if the correct police will pounce on this or not, but i use a deep fryer (dont tell swmbo) with just plain cooking oil and heat the gear in that for a while. then glob up the seal with gun grease and press it on. the oil gets about 350 to 400 degrees or so, and the grease takes the heat away when you get the gear on. afterward, i get a hankerin fer some fried chicken!!

I was on a job where a coupling went on a shaft and it was a shrink fit. The shaft may have been six inches the coupling may have weighted close to two hundred pounds. That coupling was specked to be preheated to 350 degrees Fahrenheit or maybe 250 can't remember which. After it was heated it fit so sloppy on the shaft we had to baby sit it as it cooled to get the coupling in the right location.

I would say 500 degrees in your situation is excessive. See what others say your situation may be different. A heat shield from sheet metal would be a good idea, but cooling with water I would not recommend.

You're worrying too much. Just remember it's been done a million times before.

Reminds me of brazing a reversing valve in a heat pump. Two inches away from the four joints you are brazing with a acetylene torch is the guts and it's just a piece of nylon and a couple of o ring's. Once like your gear would be bad enough but you have to do it 4 times and hope you didn't destroy a $200 valve. Worry enough to be as carefull as you can be and then just do it.

Really you just need to take the chill out of it. If you actually measured it, 200 or 300 degrees would be plenty. Bake in the oven for 30 minutes or so. I'm guessing you can't get the tractor in your kitchen so use some old towels or blankets to wrap it in the moment you take it out. Of course the seal will be pre-oiled. Whatever you do, don't douse it with water!

Do you have driver made to seat the gear in place? Should be easy to find a pipe that will fit over the end of the crankshaft and weld a flat piece on one end to rap on.

I've both heated and frozen (using liquid nitrogen) gears, bushings, bearings, and other things hundreds of times to get them on a shaft, or in a hole, and done both right next to a seal many times.

Assuming the seal is made from a typical Buna-n seal material, it is going to be rated for a working temp of about 225 degrees, give or take a bit. That said, you don't need to heat the gear to anywhere near 500 degrees. With the mass of a solid steel gear, it's going to hold the heat for plenty of time for you to get it from an oven to, and back on the shaft (provided your not planning to carry it a hundred yards, plus, to get back to the machine.) so I wouldn't really worry about the 30 seconds you've been told in that regard. Still, the faster you get it from the heat source, and on the shaft, the better off you are because it will begin to slowly shrink back to size the minute the heat source is removed.

Now once you actually begin putting it on, the shaft will draw a significant amount of heat out of it in a hurry....that is when the seconds are really going to count. In other words, IF you have 30 seconds to get it on and located, you'll be extremely lucky.

In any case, if you heat the gear to around 300 degrees or so, it ought to be plenty hot to expand it enough to go back on the shaft. From there the heat drawn off by the shaft will heat the shaft in a hurry, but I doubt it will get anywhere near 225 degrees long enough to cause any damage to the seal. If, however, you are afraid it will for some reason, simply lay a wet rag on the shaft once the gear is in place. It won't quench the hot part, and cause any problems in that regard, but it will help the shaft cool, and because the two parts are in contact, the gear will cool to. The good thing is both will cool a little faster without hurting anything.

Beyond that, good luck.

500 degrees is wholly unnecessary.

At 275 degrees, which is where you should be, there is no danger to the seal, especially if you coat it in high-temperature grease.

Thanks to everyone for all of the tips! I'll try it at 300 and grease up the seal real good. Also gonna make a good driver as someone suggested. I should get to work on it again next week. We have a wedding in the family this weekend, so everything is upside down around here right now. I "overhauled" this poor thing in 1976, but I can't remember how I got the gear off and back on the crank. I see some light marks on the hub, which makes me think I may have just pounded it on there. I was 27 years old then, and my main tool was a hammer. The old tractor has served me well all these years.

Went thru this a while back with my timing and crank gear on my old 641. What I did was measured the temp in my gas grill. I have a Holland grill that gives around 275-300 f temp (actually is a sort of oven)
I wrapped my gears in aluminum foil and set them on the cooking surface for about an hour. In the meantime I got my Woodruff key on and stuck it in place with some ultra grey gasket material. I had a tool made from gas pipe (black) that would slide over the shaft and rest on the face of the gear. When the gear was hot, I placed it oriented correctly on the shaft and persuaded it on with light taps on my tool with a small ball peen hammer.
After checking the timing marks, I did the same with the crank gear.
Worked great.. just have to have your ducks in a row before you start(tool, hammer, welding gloves, etc.)
The old girl runs a lot quieter now!