I have 12F and yesterday I decided to peel off about two inches of hard snow on my 1 mile driveway. had it nicely warmed up and got about 300 yards from home when a loud noise started coming from under my feet, took my ear plugs out and got out to have a look under cab, input shaft that leads from engine is connected a gear box that was hot, very noisy like maybe a gear was slipping. tried to lift blade to go home and it wouldn't and then the noise smoothed out like gear or key had completely sheered off. walk home get truck with 20 ton jacks, lift blade, chain up high enough to back home. took bottom plate of and its full shiny brass filings like Tony Beets sluice box. Don't own a 17/16 socket so have to drive 20 miles to borrow one. What will I be looking fore after i get the big nut off? any help will be appreciated. I'm in the middle of the middle of nowhere.

Hi, Tommyrbk.
I have never been into that box under the floor but I believe you will find a bevel gear set in there taking the power from the horizontal input shaft and turning it vertical to send it up to the control box. The bearings in there may be brass or bronze.

I would also check the sheer pin on that vertical shaft to see that it is still in one piece. I missed out on any experience with the F series 12s, going straight from the older style 12s to the full hydraulic 12Gs but I suspect that the 12Fs would have had a sheer pin in a box at floor level inside the cab. If they are anything like the older machines in that department, there will be two flanges on the shaft. The top one will have a hole in it through which a sheer pin is dropped and the bottom flange will have a hook built into it to catch said pin and send drive up the shaft.

The sheer pin in the older 12s was 3/8" diameter and many people would simply drop a 3/8" bolt in the hole as a replacement if they broke a sheet pin - NOT recommended as the proper sheer pins were made of somewhat softer material so that they would sheer first in the event of a problem.

Hope this helps.

Just my 0.02.

I believe there should have been oil in there.

Hi, kracked1.
Yes, there should have been oil in there, 90 weight, I think. But only in that bottom bevel gear box. The sheer pin boxes don't have oil in them.

Just my 0.02.

You are correct Deas as always. Your knowledge of these blades is amazing.

Hi, kracked1.
Thank you for your kind words, Sir. But I have been known to be wrong, not surprisingly since all my work with these jiggers was over 30 years ago. When I first started operating them seriously - - - - - as opposed to using one to pull a plow - - - - I found that many of the men who were already operating them had little to no knowledge of what made them tick or of any adjustments that there might be to compensate for wear. I made it my business to find out.

I once encountered a gentleman who had been operating the same Cat 12 17K series - the Australian-built equivalent of the 99E - for 9 years, 4 as an employee and 5 as an owner-operator. He was a good operator - - - - - as far as his machine handling and his work production were concerned. He was complaining that the controls were kicking back a lot now so I asked him if he had ever adjusted them. He said, "There's no adjustment on them."

I spent 2 hours on 2 consecutive nights doing the adjustments and showing him how to do them. The next day, he exclaimed that it was a different machine. That made my work and my study time worth it.

That was in 1984 and it was the last time I was into the 'gizzards' of one of these machines.

Just my 0.02.

yes there was oil in there but it was extremely "runny" and about pint or more. I purchased this machine from a township about 5 years ago that had little or a no maintenance program and have been fixing and making it better a bit at a time. when I purchased it it needed a serious cleaning and was scraping the floor clean and it was about 2 inches deep of gravel and mud and kept hitting a hard object with my scraper and thought it was a bolt, turned out to be the dipstick for the gear box that hadn't been checked in years. All new fluids except that gear box as its level was good. I only get a maximum of 20 hours a year and love to use the snow wing in March to push the banks way back. A much nicer machine then the 212 with the pup motor that i used to have. converted it to electric start with good advice from "Old Magnet" on this forum years ago. Cold and windy here, Minus 15 C and today so won't try to work on it till it calm's down. I have the parts book but can't seem to figure what page its on. Serial # 59H413F. Thanks in advance for all the input.

Glad to hear there was oil in there. Believe it should be 50w gear oil.

Hi, Tommyrbk.
You may - or may not - find something useful in this thread.

www.acmoc.org/bb/motor-graders/13254-cat...graders-pre-g-series

Just my 0.02.

that is a great article. well written and understandable. In my earlier post i had mentioned that i had taken the bottom plate off the gear box and it had oil and filings in it. It has drained out nicely and i can see that the teeth on the gear are all worn. I took the cotter pin out and tried to take the big nut off bit no luck so applied a little heat to warm it up (outside temp today is minus 12 C) no luck. Looked closer and it looks like there is a castellated nut and is it a lock nut for the main nut? Does that sound correct and jog anybody's memory? it wont come loose yet either but it was starting to get dark and i got cold sitting on the ground. most of my youth was wasted fishing and hunting