Brush Hog Complete Service in 12 Minutes

Brush hogs are known by many names; I own a Bush Hog, but the advice applies to all brands of brush hogs.

Not long ago, I needed to service my Bush Hog so I thought it would be a good time of year to do a front-to-back service. You really should do it every time you take the bush hog out to use…but if you don’t, be sure to do it as often as you can.

If you have a leaf blower, go ahead and clean the brush hog off; it’s a lot easier to work with the attachment once it’s free of debris.

Takes Only a Few Steps

The first thing I do is  remove the PTO shaft and grease everything on it; this is really important to help prevent rust. I include the U-joints, the shear bolt assembly, and the plastic shield. I’m fortunate to have a PTO shaft that comes off easily from the gearbox, so for me, it’s a fairly easy job. Even if yours takes a bit of work, don’t skimp.

I use a LubeShuttle pistol grip grease gun, and recommend them highly.

Next, I get a 15/16″ socket and open end wrench and tightened all of the bolts on the cutter. Brush hogs have a lot of vibration, which tends to loosen bolts. I hit all of the bolts on the A-frame, the tail wheel assembly, and the gearbox. There are quite a few bolts, but you don’t want any of those bolts to get loose.

Clean Oil is A Necessity

My check of the gearbox oil comes next, and this time it shows I have enough oil, but it was a milky color. That means it has drawn some moisture. That could have come from humidity, and it’s pretty normal when you live in an area that has a lot of moisture in the air. There is enough lubricity there to bush hog a few more acres, so I decided to wait. I do need to change it, though,  and I’ll do that in a future video. On my machine, you have to use a suction pump to get all of the oil out and replace it with new.

After that, I grease the tailwheel, including the yoke that attaches it to the bracket, and the wheel itself. (Tail wheels take a beating and need a lot of lubrication.)

Under the Machine

Finally, I get my flashlight and looked under the machine for anything wrapped around the shaft that leads to the blade pan. It’s not uncommon to find baler twine or wire around there, and left unattended, either type of material can run up the shaft and take out a seal and fail a gearbox. Fortunately, everything is fine under there today.

Now, I had set the brush hog up on some blocks to level it while I peered under it. If I were going to actually crawl under it, I’d be sure to use several jacks to ensure it would stay up.

I also look at the blades, which are extended.  This is an important thing to check, because if you hit something in the field it can push a blade up into the blade pan. Having one blade out and one blade in can just about shake you off the tractor seat. Also check carefully for twine under the blades. Tangled twine is always a problem and can cause failures if  wound up in the blades. And it can also move up and actually take the seal out.

Outside of needing to change the milky oil in the gearbox, everything looks good, so I’m ready to go back to the field and continue brush hogging with a clear conscience.

A Quick List of Useful Tools to Have on Hand for This Job

I keep mine in a separate container under my workbench so the right tools are always at hand for brush hog maintenance.

They are:

  • Lube grease gun
  • Flashlight
  • 80W90 gear oil
  • Bungee cord to hold cover of gear box out of the way
  • Rag
  • Paint pencil
  • 15/16th open wrench and 15/16th socket adjustable wrench  for checking bolts
  • 5/16th Allen wrench for opening the oil plug on the gearbox
  • Level – so you can level the machine and be sure the gearbox is level for checking oil

Tractor Mike


  1. Earl Wagner on at 19:49

    Why did you leave out servicing the slip clutch. I watched the video you did about this and it seemed pretty important.


  2. John Rempe on at 21:09

    I have same Bush Hog Squealer cutter and did not realize pto shaft came off so easy. I rarely check bolt tightness but will now along with your other suggestions.

  3. Geno Clemans on at 14:20

    Thanks Mike

  4. D. Vance Baugher on at 14:29

    Retired Engineer commenting here: you need 4 to 5 pto hp for each foot of brush hog cut in normal operations. Contrary to many people I keep two sets of blades for each of our brush hogs. You want a brush hog to rip the vegetation rather than a clean cut. However, I have found keeping the blades dressed to about a 3/32 blunt edge and no more saves me a gallon of diesel fuel for each 10 acres. That’s blunt enough to rip more than cut and sharp enough to save fuel and ease the strain on U joints and gear boxes as well as less strain on the tractors pto system. Changing the blades periodically ensures inspection and keeps things from rusting in place. I’ve found no way to keep condensation out of the gearboxes. Therefore, I start each season with a thorough inspection, use about 1/2 hour to warm up, drain and refill with gear lube

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