Rotary Cutter Brush Hog Blades

[jrheinemsn]

Good morning all,
I am a newbie, just picked up a JD 4100 and a beat up no-name brush hog.
The hog is a single spindle with two blades.
My question is are the blades supposed to swing on the attachment points?
The blades on my unit are stuck at 90 degrees behind the attachment bar, which severely decreases the cutting radius.
The blades are attached to the bar with 1-3/8" bolts/nuts, which i have yet to loosen up.
Any thoughts?
Thanks

 

[Btown]

The blades should spin freely at the attachment point. They are supposed to turn if you hit a rock or tree stump or something. Then the rotational force will straighten it back out. Does it shake when you turn it on.

 

[kebo]

A picture here would really help, but yes, the blades should swing freely on the two bolts that they are attached to the pan (or stump jumper) with. This is to allow them to swing back (deflect) whenever the blades hit something hard or immovable, a design feature to help protect the blades and the gear box.

Sounds like they are bound up, maybe with lots of cutting debris in the joint, or just rust from having set up for awhile? If you cannot loosen the nuts holding them in place, then you'll need to figure out some way to get them to rotate slightly. Maybe use a hammer on them? Really though, it sounds like you need to get those bolts freed up so you can remove them, clean them up good, and add a bit of grease so they'll swing easier.

Removing the nuts from the bolts can be quite challenging at times. They may be torqued on, and it will probably take a combination of an impact wrench, a breaker bar, some heat from a torch, lots of penetrating fluid, a little bit of blood, and definitely some cursing to get them off. Good luck!

 

[jrheinemsn]

Id doesn't shake at all, the blades just seem to be stuck against the attachment bar.
So they are supposed to rotate 360 on their attachment point?

 

[jrheinemsn]

being a newbie, I think I have mastered the cursing part.
I'll go get a breaker bar in the morning and see if I can get them loosened up.
Thanks so much for the help.

 

[JimRB]

My owners manual says torque blade bolts to 433 lb/ft. Other manuals say 600 lb/ft. Figure it should take more to break loose with a bit of rust. There is more drama getting the bolts out even after getting the nuts loose. If it were me I would be spraying some Kroil or PB Blaster on the bolts and focus on getting the blades to swing freely. On my brush cutter I can spin the blades 360 dgrees with little effort. As mentioned the blades are supposed to fling out to full width when running the mower at full PTO speed of 540 rpm.

Here is a manual from Bush Hog that explains lots of concepts you should be aware of. You can go find other manufacturers owners manuals. http://www.bushhog.com/uploads/documents/BHRotaryCutterBH10SeriesOM-15.pdf

 

[RalphVa]

I bought a 3/4" drive and a 6 foot piece of steel pipe to go over it as my "torque wrench" for removing and tightening the bolts on the bush hog. You'll access them either through a hole in the deck or underneath where the trail wheel is attached. On both my bush hogs I've had, they accessed through the crack in the deck where the trail wheel goes.

You'll need 80-100# push on the end of a 6 foot "torque wrench" to get those bolts loose and to tighten them. Make sure the bush hog is securely in place to prevent side-to-side movement and up on jack stands before you ever think about going underneath there.

On my 1st bush hog, I needed a couple clamps to hold the blade, bolt and stump jumper in place when putting the whole mess back together.

Make sure your socket fits the hex heads on the nuts exactly. Don't try to use one of those with jagged edges around the inside and expect it to hold.

Ralph

 

[franklinute]

If you can reach underneath the mower safely I would use a big hammer and see if you can get the blade to move
by hitting it on the back side of the cutting edge. Even if it moves a little the spinning force while running should
straighten the blades. I have several bush hog brand and non brand cutters. I use a 1 11/16 socket on a 3/4"
impact gun to remove the nuts. With the nut and washer off I tap on the center of the bolt with a 1" solid rod and
the bolt and blade fall off every time.

 

[johnems]

Is anyone aware of a push/puller device to remove the bolts? Thanks John

 

[Coyote machine]

I'd use a long handled sledge hammer to whack the back side of the blades to loosen them up, then rotate the unit as intended with the PTO engaged at low RPMs to start, then gradually higher RPMs until it runs as intended. Lubing the bolts on the attachment point of the blades liberally will help free then up more and keep them freed. Drain and refill the gearbox with fresh gear oil too.:thumbsup:

 

[bumperm]

Is anyone aware of a push/puller device to remove the bolts? Thanks John

To be clear, the bolts are shouldered, so when the nut is tightened up, spacing for the blade pivot part of the bolt is set - - there is no adjustment when installed to give the blades more slop to pivot more freely. What is likely making the hard to pivot is rust, dirt, and plant debris that has caught between the blade and stump jumper. Spray the blade pivot with lubricant and work the blades back and forth to loosed them.

If you plan on removing the bolts to clean and lubricate things, it's a good idea to use penetrating oil (a good one is 50/50 ATF and acetone) and let it sit for awhile before trying to remove the nuts. I bought a big 1" breaker bar and socket just for those nuts.

 

[fishheadbob]

If you can reach underneath the mower safely I would use a big hammer and see if you can get the blade to move
by hitting it on the back side of the cutting edge. Even if it moves a little the spinning force while running should
straighten the blades. I have several bush hog brand and non brand cutters. I use a 1 11/16 socket on a 3/4"
impact gun to remove the nuts. With the nut and washer off I tap on the center of the bolt with a 1" solid rod and
the bolt and blade fall off every time.

Good advice, whack it.

 

[Gary Fowler]

I have seen on at least some bush hogs that when both of the blades swing under the stump jumper they will lock together and have to be pried apart. I suspect that is what has happened to the OP's mower. He just needs to get under it and beat, pry etc. to get them apart and then they should work ok.

 

[STx]

Some of the blade bolts are reverse threaded, check that before you start putting a bunch of effort into removing them to be sure you're not tightening them instead.

 

[DFB]

Whack 'em with hammer to get them loose we get them jammed all the time.

Make sure your block and secure your equipment to be safe underneath.