Hi Team,
seems the pages for the 22 clutch were short of a 3rd page that covered the single bolt sliding adjustment for the clutch brake to follow up the wear od the main clutch disc.
Link below has the OMI that you should be able to get the needed info from--alas I cannot post any more pix since last BB upgrade.

www.angelfire.com/home/cat22/book/manual.html

Hope this helps.
Cheers,
Eddie B.

Big or small Twenty

I have a big 20 all apart now and it is very different than a small 20 as far as the clutch and clutch brake, I can post some good pictures of the big 20 clutch brake later today. I will have lots of big 20 parts for sale if someone needs them including a nice clutch brake.

I do not see a way to adjust the position of the clutch brake on a big 20, the casting that holds the clutch brake lining is bolted to the transmission input shaft and should be fixed. In the pic with the brake without a lining the travel of the brass thrust collar was enough to tub metal to metal without a lining. Based on that I would suspect you are not getting full travel of the brass thrust collar maybe due to worn fork or maybe the casting with the lining is loose on the input shaft, wore out the splines and has worked its way back, a 1/4 inch makes a big difference.



I am heavy into a big 20 project building 1 nice wide tractor using 1 1/2 other 20's for parts so I got lots of big 20 parts I would be happy to sell for cheap if picked up, I would ship small stuff to help along someones project.

Steve, there is a guy from Australia looking for some good bottom rollers for a 20. I am parting out L836 but the shutdown has brought me to a halt. If you want, I can PM you his contact. Grant.

I do have good rollers, if he has a good way to transport

I am going to be a little more direct here. If you can afford to buy the machine, you can afford to buy the books for the machine. Sometimes you can find a good deal on Ebay, other times from club members and if all else fails Cat will reprint the books for you. Read and study the books like you were going in for a Bar exam. Caterpillar instruction book form # SL991 is an excellent book for the L/PL Twenty going through operation and tear down and repair of the tractor. Now for the measurements on the clutch brake disc taken from Form # SL795 "L663 Facing for flywheel clutch brake. 5 3/4" O.D., 4" I.D., 1/4" thick. 4 countersunk holes on 4 7/8" circle." All of that being said, the pilot bearing on the L/PL twenty has no good means of lubrication except at assembly or repair of the clutch. If the bearing is dry and or the lubrication that is in it is dried up it will cause the clutch to drag and no amount of clutch brake will help fix the problem. The solution is to split the tractor, clean and or replace the bearing, if you can find one, relube the bearing, replace all lining on both the clutch and clutch brake, replace or rebuild all worn parts and be done with it.

Hi Neil. I just let my brain wander on your question, sorry if I say anything that might offend you as I do not mean to, it is just the way I write. When I went to the shop last night I was going to look at an extra clutch that is on the shelf and a trani case. I forgot and played with other things. I have attached pictures of the Twenty clutch from one of the parts books and the sales book. I have also attached a picture of the clutch from an early RD6 to show others what you are talking about and one of the problems I see with trying to do this. The biggest problem I see is access to the grease fitting one it is installed. The Twenty clutch is almost completely covered by the L686 housing. There are windows in the outside of the housing that could be used for access, but this would require you to line up the fitting with one of the windows. The next problem is how do you access the fitting from outside the machine. The cover on top of the case will not work, it is barely big enough to get into to adjust the clutch on the late machines and is much smaller on the early machines. The idea thing would be for the another access point. Do you drill a new hole through the case and then make a cover for it or thread it for a plug. If the clutch compartment drain hole in the bottom of the case lined up it could be used. That is one of the things I was going to look at last night. Then there is the fun of not only lining the fitting up with the holes in the L686 clutch cover, you now have to line the whole clutch up with the access hole in the trani case. Not easy but not impossible. The other problem that I see is there is not a system designed in the Twenty clutch to deflect the grease away from the clutch plates. If you look at the picture of the RD6 clutch there are some basic seals and deflectors on the plate to try and make sure that the extra grease does not get on the clutch plates. The Sixty uses a bushing in the middle of its clutch plate which is lubricated with a grease cup. The Sixty also has no seals or deflectors to keep the grease out of the clutch facings, so there are examples of a greased type clutch bearing without grease deflectors. I have a PS Thirty that is having its clutch hang up. When I have time I will pull it out and work on it. A big difference between the Thirtys and Twentys is that I do not have to split the tractor on the Thirty to get the clutch out.

This has become an extremely informative post for myself and Jeff M.
He recently acquired a nice Twenty which has clutch brake issues as well.
Neither of us claim to be mechanics, but with all of this information, it gives us much better idea of what we might be able to do in resolving his issue.
The closest “ old timer” CAT guys around here are an hour away, and don’t really provide anymore mobile wrenching. This may save us a lot of grief if the adjustments can be made without the painstaking effort of transporting his crawler to either of them.
The local dealer is only 10 miles away, but if the “kids” can’t plug into a diagnostic port, they wouldn’t have a clue.
Glad that there are valuable resources here on the BB.
Thanks everyone!