Bushhogging Basics

Anonymous Poster · Apr 21, 2003

I'm sure some of us newer tractor owners would appreciate some pointers from the experts on proper bushhogging techniques. I have several questions

1. While BHing, is the "tail wheel" supposed to be carrying the weight of the cutter? Or does it ride just above the ground?

2. With at least 3 adjustment points (Tail wheel, Top link, Lift arms), is there a simple solution to adjusting the height of the cutter? Or do you just "play around" till you get it right?

3. My unit is an "Agri Four" and it is loud!! It sounds like it's going to fly apart. Shaft is straight and U-Joints are lubed. Sounded like that at the dealer and he didn't flinch. Any comments?

Thanks to those who have helped so far,

Rick

RoyJackson · Apr 21, 2003

1) I have the tail wheel on the ground.

2) LOL! I "play" around! Actually, I set up on a fairly level spot (driveway) and "eyeball it level fore and aft as well as laterally. Although there is adjustment in the tail wheel, I never touch it...top link pretty much does it all for me.

3) Yep...wear ear plugs or muffs!

I borrow a 48" cutter from a friend to mow about an acre twice during the season, so I'm no expert. The area is mostly vines and brush...nothing too heavy. As it doesn't belong to me, I prefer not to do any adjustments on the cutter. As set, it cuts to about 3"-4" high. Good enough for my purposes.

JohnMiller3 · Apr 21, 2003

…is the "tail wheel" supposed to be carrying the weight of the cutter? Or does it ride just above the ground?...

The rear wheel supports the rotary cutter and will be in contact and ride on the ground…

…2. With at least 3 adjustment points (Tail wheel, Top link, Lift arms), is there a simple solution to adjusting the height of the cutter?...

Normal cutting - The front end of the cutter should be 1 – 2 inches lower than the rear, with the front skid plates “gliding” in the air 3-4 inches above the ground surface… (actual height will depend on terrain, rocks and boulder terrain usually being the highest) This position uses the least tractor’s PTO hp… (most efficient!)

Mulching/grinding cutting – The front end of the cutter will be level or 1 – 2 inches Higher than the rear, keeping the cut debris “for a longer period of time” in the cutting path of the blades, generating a “mulching” action of the debris vs just “shearing” action. This position requires the most PTO hp action to sustain operation.

Most tractor’s position controls will have a “lock/stop” you should adjust to prevent the cutter from riding into the ground or on the surface. (When traversing streams/creeks, short fast changing ground terrain, etc. you will bring the cutter into the transport position and then need to lower it “quickly” back to normal terrain… is where this position lock/stop is mostly used)

…3. My unit is an "Agri Four" and it is loud!! It sounds like it's going to fly apart…

Most rotary cutters are nasty sounding to begin with… /forums/images/graemlins/blush.gif ( also God’s reminder of how dangerous and unforgiving they really are…)

Just verify your blade bolts and pan assembly are torqued to the proper spec’s, your gearbox is properly mounted to the deck, and your PTO drive shaft male/female sections are synchronized (if not it will vibrate/shake and be ultimately dangerous… and cause mower fasteners to vibrate loose and “fly apart”…/forums/images/graemlins/shocked.gif)

JackIL · Apr 21, 2003

John just gave an excellent summary of the adjustments, but there is one further detail. The top link (or chain) needs to be slightly slack when the cutter is in the level working position. This allows the cutter frame to attempt to follow the contour of the ground as the tractor passes over undulations. Of course when traversing very sharp changes in grade there may not be enough "slack" and the cutter will either gouge into the ground or be pulled up in the air higher than desired.

On many cutters this is provided for by a short link between the cutter mast and the connection to the top link. Some others use a slotted arrangement or chains to the rear. Some people just use a chain instead of a solid top link, but this allows the cutter to flip way up if its front edge strikes a tall stump so it is not as safe and may damage the PTO shaft.

One further point. Most tractors have "position control" that allows you to return the 3 point linkage to the same "down" position every time you lower it. This is how you maintain the height of cut at the front of the BH. However, there may be "leakdown" in the hydraulics that allow the cutter to slowly sink and therefore not maintain a level cut from one end of the field to the other. Some tractors have no position control on the 3 point hitch. For those there is a simple solution in the form of "check chains" (an accessory available in most Farm Supply stores) that limit the amount the draft links can be lowered. These attach to the tractor top link pin and run diagonally down to the connection pin on the rear of each draft link. So for this situation, the front height of the cutter is adjusted by selecting the proper links in the check chains and then just lowering the hitch until the chains are tight.

Hope this helps.

JackIL

RoyJackson · Apr 22, 2003

"Just verify your blade bolts and pan assembly are torqued to the proper spec’s"

This is an extremely good point. Torquing (and the use of anti-sieze compound) ensures not only the unit stays together...but also that you can disassemble it when the time comes for maintenance. But you do want to check the torque (to ensure they aren't loosened by vibration) every so often. A unit like a rotary cutter...I'd check before each use. The cutter I use, a Deere 413, isn't used by anyone else (just can't talk the current owner into selling it to me), so I check the torque prior to using it...got to borrow a torque wrench to do it....the bolt is around 200 ft-lb, if I recall correctly. My wrench only goes to 140 ft-lb or so.

Use your airgun to remove fasteners, friends. Use your torque wrench when you're assembling them!

djradz · Apr 22, 2003

For the best cutter positioning under most situations I'd suggest you do a search of TBN under the subject of "check chains". There is a great deal of useful information under the many posts you'll find as well as a few photos.

chrisjbell · Apr 22, 2003

However, there may be "leakdown" in the hydraulics that allow the cutter to slowly sink and therefore not maintain a level cut from one end of the field to the other. 

Yup, this is true - I've found that the "leakdown" process can be slowed by setting the valve that controls how fast the 3PH to the "Closed" position. Seems to prevent the 3PH from dropping as fast. On the other hand, that makes it a bit tougher to drop it when you have to adjust it...

Oh, keep the wheel in back on the ground at all times, especially when going up a hill. If you have lots of weight in front you will probably be OK, but if you get light in front it is quite possible to flip the tractor on its back, with you under it. This is one of the more common ways people kill themselves with a tractor (a fun tool, but also a pretty dangerous one if not used with great care).

BB_TX · Apr 23, 2003

OK, you have arroused my curiosity about leakdown. My 3pt leaks down very slowly after I kill my engine. However, as soon as I restart it, the 3pt goes right back to the original position and stays there as long as the engine is running. Are you saying yours drops even with the engine running?

froggy · Apr 23, 2003

John,

Thanks for the tips.

froggy

chrisjbell · Apr 23, 2003

However, as soon as I restart it, the 3pt goes right back to the original position and stays there as long as the engine is running. Are you saying yours drops even with the engine running? 

I don't have position control, so mine doesn't return to a previous height. But yes, when I'm bouncing around the field I think that I do get a bit of leak down even with the engine running. I know that every so often I have to pick the deck up. I suppose it is possible that I bump the lever by accident and don't realize it, though. /forums/images/graemlins/confused.gif

JerryG · Apr 23, 2003

( Some people just use a chain instead of a solid top link, but this allows the cutter to flip way up if its front edge strikes a tall stump so it is not as safe and may damage the PTO shaft.)

Not to pick on Jack, this has been said here several times over the years. But, I use a chain like this and have never had a problem and I have worked at a tractor dealership and been around farm equipment all of my life and have never seen or talked to anyone that has ever had this problem. Now to my question. Has anyone here ever had a bush hog flip up when using a chain in place of the third link or ever actually talked to anyone that has been injured from this practice?

JackIL · Apr 23, 2003

Well not exactly, but almost. A few years ago, an after-hours landscaper I know bought a new JD 503 Rotary Cutter to use with his JD 970. On his first paying job with the cutter he was mowing in tall grass when the center of the front edge of the deck caught on an old concrete foundation hidden in the grass. The jolt was so severe it bent the leading edge of the deck, bent the PTO shaft, and bent the mast and braces. He was using the solid top link. The deck did not strike the tractor, but must have tilted up quite a bit based on the damage done to the cutter.

I am not aware of any rotary cutter manufacturer that condones the use of a simple chain instead of a solid top link.

JackIL

Soundguy · Apr 24, 2003

The chain toplink is no more dangerous than using the rotary mower in a 1pt pull configuration , I.e. from a drawbar. The same hazards for the pto are involved, etc.

I have a neighbor with an old jd with no 3pt lift. He pulls a TSC branded mower like that from a swinging drawbar.

The TSC mower ( like mine ) came with assembly instructions to set it up for either 3pt or 1pt hitching...

Soundguy

BB_TX · Apr 24, 2003

Chris-I am thinking you are correct on the lever although it probably moves down by itself due the bumps, bounces, and vibration. Otherwise, if you kept raising the lever, and the implement kept leaking down, eventually the lever would be at maximum and the implement at minimum and you would have no way of getting it back up.
Sorry. My little engineer brain can't help but over-analyze these things. /forums/images/graemlins/crazy.gif

djradz · Apr 28, 2003

Absolutely!!! /forums/images/graemlins/cool.gif I keep hearing talk about the dangers yet no one has ever had a mishap. /forums/images/graemlins/frown.gif I agree entirely, trailer/drawbar implements have been around since the beginning of time (tractor time that is) and are proven very safe, and those implements are held with only one point. I'm not necessarily advocating a chain for a top link, because I like a swivel type instead for allowing deck "float" but I think we're overly critical of the chain top-link substitute.

GaryK · Apr 28, 2003

I switched to a chain top link after getting stuck in the mud with the old setup. My neighbor got his stuck the same way and put a chain on his too. I have hit some interesting things with the bush hog and I have never observed it to jump up to a point that it was dangerous...

GlennT · Apr 28, 2003

I have a four-foot Bush Hog and I did have it jump into the air a couple of feet or so when I hit a stump hidden in tall grass. Boy does that get your attention. Nothing was damaged, fortunately--probably because I wasn't moving very fast. I imagine a larger, heavier shredder wouldn't have hopped into the air so readily. I use a heavy piece of chain with a clevis to connect the top connector of the Bush Hog to the top of my quick hitch. The chain is attached to the quick hitch with a 3/4 inch grade 8 bolt. Overkill? Maybe, but I feel better about it.

bmac · Apr 28, 2003

I'd like to add another question. I live in a residendial subdivision, however my rear property line borders woods. The briars, saplings, vines and scrub are slowly encroaching on my yard. Is it any less safe to back into the overgrown area with a bushhog as opposed to driving forward? I'm only trying to reclaim a strip 10-15 feet deep. The trees deeper in woods would prevent me from driving forward.

Bird · Apr 28, 2003

bmac, there's nothing unusual about backing a brush hog into stuff that needs cutting. It's done frequently.

Anonymous Poster · May 1, 2003

John, (and everyone else)

Thanks for the tips. It was necessary to adjust the tail wheel to get the desired cut height. Top link was used to fine tune the angle. As you explained, I set the "stop" at the desired height and after digging the BH into the ground a few times, learned to "raise and quickly lower" at the appropriate times.

Rick