New to forum. I recently bought a Cat Grader at an auction. The only information the auction house gave was that is a Model 12. The S/N is 80C277. You will see the tag in one of the attached photos. If more photos are needed, please let me what is needed. I may not be looking at all the posts, but the ones I have read here that lists S/N's, I cannot find this one. Starting to work on the machine, and have so many questions, but will begin with asking you guys to identify the Model and year. Thanks, and I am so glad I found this forum.

1956 model.
Direct electric start
D318 4.5" bore 6 cylinder engine
Oil clutch (possibly shares oil with engine like the 99E series that followed?)
Manual/knuckle buster controls

Thank you, CCJersey. Is my machine just a plain Model 12 ? In regards to the clutch. That is one of the issues we have found. It is a wet clutch. We are trying to adjust the linkage, but it is about taken up. I will get some close-up photos of that area. Brakes. None. Want to start with replacing the master cylinder. I have no idea where to look for a replacement.

The adjustment for normal wear is made inside the clutch housing by removing the cotter pins and adjusting the castellated nuts on each release lever until the specified clearance is obtained between the pad on the lever and the face of the release bearing. The 99E book specifies 1/8" but my old 212 book said 3/16" for that dry clutch machine. I would guess 1/8 is more appropriate for your machine since the 99E was the next major model replacement for your grader.

I have had good luck matching up brake cylinders at my local NAPA autoparts. There are always casting numbers etc on the cylinders. The last one I needed was for a wheel loader and turned out to be a Wagner. Caterpillar usually has a source if you have the part number or can get them to get off the computer and go to their microfiche machine to look it up. They can also order parts books, service manuals etc if you cannot find anything on ebay or the classified ads here etc.

The problem with the brake wheel cylinders is the only way to get into them is to pull the wheel off the axle. Takes a heavy puller to get it off and needs pressing back on the tapered axle at 20-25 tons DRY fit. That is one reason a lot of them have no brakes!

I like the alternator tensioner you can see in one of the picks. That is some of the worst damage I've seen on a grader blade. You don't say where you are. If its near southern Alberta I have a spare blade I could part with. The oil clutch is definitely adjusted inside the housing. I could scan those pages for you if you need them. I got new discs from General Gear for mine. Not too bad to change, but that old engine is heavy.

Good luck with your new machine
Captain K

Master cylinder part number is a 5B3217. Only one I could find on the net is at F.P. Smith in Ca.

Thanks so much fellas for responding to my questions. You can probably tell that I am not a mechanic. I am the searcher for the mechanic, so I hope I do not loose any details in the translation. Some follow up answers and questions:

1. CCJersey - Thanks for the info on the clutch adjustment. Will pass this on. In your comment about the brake wheel cylinders, you write on the difficulty of getting the wheels off the axles. The two back tires are going to need to be replaced. Is this something within the wheelhouse of a local tire dealer? They replaced a tire on an 81 fire truck I have, on site, but this maybe a different matter. I presume this could be a good time to look at those wheel cylinders as well?
2. Captain K - I am in Alabama. Not far from CCJersey. I thought the alternator tensioner was just a band aid, but mechanic said good solution to the not so reliable generators. Yes, please scan the pages that you have that might could help. Don't know all the rules here, but if it would help if you want to email those to me, here is my email address: <a href="This email address is being protected from spambots. You need JavaScript enabled to view it." target="_blank">This email address is being protected from spambots. You need JavaScript enabled to view it..
3. Old Magnet - Thanks for the info on the master cylinder. I have already reached out to F.P Smith to get a price. The mechanic does not want to tackle removing the engine. He is an older guy and does not have the equipment to remove it, so we are trying everything to get the machine going, outside of that.

Overall, the machine is running good. Oil looks and smells good. The control levers are chattering, but the hydraulic fluid was very low, and he is adding that today. My biggest concern is getting that clutch to work. We will need a village to get that going without pulling the engine. My thanks to all, and I am sure there are more questions to come.

Yes, entirely different matter removing hub from axle vs removing rim from hub and tire from rim. You will need a heavy equipment mechanic with a hydraulic push/pull setup to remove the hubs from the tapered axles Though it can be rigged around with jacks etc, its hard to explain how to do it and you are dealing with some potentially dangerous forces. Things don't usually fly far but if you are close or touching something that pops loose, it can do damage!

Just a note, only one rear wheel on each side has brakes so you only have to remove at most 2 hubs to do all the brake repairs. You could also get the hand brake working well and use it and the big steel 12' wide one under the bottom to get by!

To change tires, the rims can be frozen rusted on center hub pretty solid after you take the clamps loose. I had one I couldn't punch out with a backhoe bucket. Finally got angry and beat on it with a 10 pound sledge hammer and lo and behold it popped loose! That was in the process of fixing a small 212 grader I bought that the hub had not been pressed on the axle properly and came loose later. Previous owner had kept running while it ruined both the hub and the axle so both had to be replaced when I got it. Last job was to get old wallowed out hub out of rim and it just didn't want to let go.

The control box in the cab with all the levers is a type of dog clutch mechanism. There are 6 functions that move two ways (push one way and pull the other)

Unlike a normal clutch with disks that slip so things start and stop gently and smoothly, these clutches have coarse teeth (dogs) that mesh with another similar set of moving teeth when you push or pull the lever. So unlike a disk clutch, you must move the lever quickly and forcefully to engage the clutch to move whatever you are attempting to move and disengage quickly when it is time to stop moving. With time and use, the engaging surfaces of the dogs get worn and no longer grab as well resulting in the dogs moving back apart in spite of your best effort pushing or pulling them together with the lever. The result is at least an irritating chatter and at worst a painful jolt to your hand and wrist. A good pair of gloves helps a little.

The hydraulic system on that one is just the power steering. Some graders of that era used it for shifting the blade moldboard left and right with a long hydraulic cylinder on the rear of the blade frame. I don't see that in your pictures so yours just has the normal mechanical side shift. On second thought there is a lever missing from your control that might be the side shift. It is possible that someone locked that in the middle and took the lever off because of damage to some part of the mechanism.

My uncle was very pleased finding truck brake master cylinder was the same as his 8t No 12 grader used.I believe the wheel cylinders were as well.

He was very happy to have brakes on a 8t grader and a DW 10 scraper as most don't work.

&quot;Ray54&quot; wrote:

My uncle was very pleased finding truck brake master cylinder was the same as his 8t No 12 grader used.I believe the wheel cylinders were as well.

He was very happy to have brakes on a 8t grader and a DW 10 scraper as most don't work.

Yes, for the most part CAT sourced their brake components from common manufacturers of the time like Wagner Lockheed, Bendix etc. My NAPA store has been able to find repair kits or whole cylinders etc for most of my projects.

I remember some years back a thread discussing a #12 that overturned when the brakes failed on a hill.