Rotary Cutter gearbox maintenance

was preforming some Howse rotary cutter maintenance this afternoon,

ran the cutter for about 10 mins then brought it to the shop to sharpen the blades and check the oil in the gearbox.

got blades sharpen, then took the small plug out of the gearbox, milky oil shot out of the gearbox.

so I guess the gear oil has water in it for it to be a milky color and the gearbox must have had too much oil as a lot of oil ran out.

I assume the top vent plug is stopped up as the gear oil was under pressure when I removed the lower small plug.

So I started cleaning the top vent cap and got a piece of wire hung in it. Had to drill the wire out, but got it cleaned out as I can blow air through the vent plug.

next problem, the lower plug is my oil height plug and the gearbox is full of dirty milky gear oil, there is no plug to completely drain the gearbox.

so my plan is to lift the cutter up with my boom pole and let all the oil drain out of the gearbox, then refill to the proper level with fresh 90 weight gear oil.

Others have said to use tube grease, but since my gearbox is not leaking I plan to stick with gear oil for now.

maybe if I get all that done today I can start cutting grass and weeds tomorrow.

hope you guys have better luck preforming rotary cutter maintenance than I have had so far.

Fairly typical, condensation or something. You could flush it with kerosene or diesel, if there is no harm in doing so, seals or what have you.

I welded a hook on my rhino SE-6, and use that to hoist it and place it upside down, to drain the oil out. They are a bit awkward to handle, but with a loader, and carefully rigged, it should not be too difficult. You could use a siphon of some sort, but I preferred to drain mine, it gave good results, as the lube stays clean now.

This one pressurized this year for some reason, so I kept checking it, releasing the apparent extra oil, I thought it was water as I usually service it once a year, but having done so in the past, the oil was clear, clean and either I overfilled it a tad or what, its pretty simple with the level plug, just not like me, maybe it was not level, they don't hold much. It was hard to believe it was overfilled, now fine, thankfully I kept releasing the excess every few rounds. This older one has no vented fill plug. So most of the excess ran out, I kept checking as this can make the shaft seal fail if I read it correctly, this one calls for 18 ounces of NLGI 000 lube,(Alamo Part No. 00765444) I could not find it conveniently last time it was serviced, so I used a Lucas 80W-90 or 90Wt, I forget, no problems, been at least 2 seasons since it was changed, probably cut 10-12 acres or so per year.

Some never service these, often times like a differential, I don't subscribe to that, they don't hold much, upside down it all drains nicely, inexpensive lube change, mine was coffee color oil, seems to stay clean now, next season I'll put new blades on and service it again.

I don't believe tube or any similar grease is really meant for these, people do it when seals fail, some swear by it, its splash lube in my eyes, designed to have a specific lube, per the book on mine, NLGI 000, and or corn head grease would be similar, maybe even the old crawler track roller grease stringy like bar oil. Tube grease settles out, soap base and oil with age, that will make a mess inside a gear box, in my humble opinion, if a seal goes, why not just fix it, these are not complicated to repair. On mine, the stump pan comes off easily, then the gear box, could be on the bench within an hour.

thanks for the reply,
I am a certified KY redneck, so I went another way,

I leveled the cutter, then took both upper and lower fill/drain plugs out, then started tractor and let it idle with cutter running,

this action pumped the oil out of the lower hole, am sure I did not get all the oil out, but enough for me. I refilled the gearbox to the proper level with 90 weight gear oil.

I plan to run the cutter for a few hours then drain the gearbox again using the same method, that should get 80%+ of the old oil out of the gearbox.

time will tell if it works, if not and the gearbox starts leaking, it will get lubed with john deere or caseIH cornhead grease.

You can buy a suction gun pretty cheap. One tool in my box that is not used often but when you need it, it's really handy.
You can also use it to fill a case by sucking up new gear oil from container and shooting it into the case. With a 18 inch clear plastic tube on it you can fill a case where you could never get a container in there.
Mine looks like a grease gun with no pump handle.

The moisture is condensation. Now that you have the vent unplugged next time you use it the heat will drive that residual moisture out.

I was curious about NLGI 000, and while doing some reading on the web, I decided to look up JD Cornhead grease, figuring it has to have a NLGI designation. Cornhead Grease is NLGI 0, by description its thicker, less viscous than 000, for low speed gear cases such as row unit gear cases on JD cornheads. 000 is described as the consistency of cooking oil, while 0 is described as being like brown mustard. So there is an obvious difference, book on mine calls for 000, not sure if a less viscous grease would be desirable, for a faster moving differential/gearbox.
Cornhead Grease

used the cutter today,

worked great, after about 1 hr, I stopped and felt of the gear box, it was warm

but, it was hot today, so I was warm too.

sure was wet and muddy down along those ditch banks. Heavy weeds and grass due to all the wet weather we have had this spring and summer.

will check the oil level again in the morning and be sure no leakage, but it appears to be working fine.