bush hog windrowing

[Anonymous Poster]

Glennmac, "We ask the same questions over and over--half the time we give the right anwers, half the time we give the wrong answers, half the time we dont know the answers, and half the time we forgot the previous answers. As you can see, it rarely adds up." - If that's not a classic it should be! Did you come up with that yourself?

Also, do all bush hogs rotate the same way, clockwise as seen from above?

 

[glennmac]

Danny, thanks. But, NO, I dont know which direction the various brush cutters actually rotate. In fact, I do have a catalog for the new Woods brushcutters, which says they all rotate CCW. My Landpride and Deere literature doesnt seem to indicate the direction.

I was just hypothesizing a direction to see if we could figure out what's going on under the deck. Of course, at the beginning of this thread I said that I really couldnt detect any windrowing with my cutter at all.

Maybe if we all knew which direction our cutters rotated and were sure which side the windrows appear, if at all, we could figure out the dynamics of what's going on underneath.

 

[Joesgoats]

I just check the parts manual for my Landpride, and based on the picture of the blades, it too rotates CCW. In that case the windrows, based on my little theory, should be on the right side, which agrees well with the one data point we have from theboman.

Joe

 

[Bird]

This has been an interesting thread, to say the least. The blades on my Howse turn in a counter clockwise direction (as viewed from the top) and what windrowing is done is on the left side, which is one reason I do most of my mowing in a clockwise direction around the field. Imagine the blades coming around and catching the grass at the front of the cutter and carrying it around the left side, so the left rear corner is the first opportunity for the blade to push it out the back. Anything the blade hits at the back or right side of the mower will be pushed toward the front since the blade is moving in that direction.

Bird

 

[glennmac]

Now, wait a darn minute. Those of us who know which way our cutters rotate are all saying CCW. But Bo says he's got windrows on the right, Bird on the left, and I don't see any windrows. What gives here?

I wonder if any of this is related to the side that discharge chutes are put on finish mowers. They almost always seem to be on the right side. What way do those finish blades rotate?

 

[theboman]

I'll look again on what side. I bush hog in all directions so I may have my left and right on the right and left or just backwards to that. I really ain't got much a clue on what direction my blades spin but "thought" it was clockwise (I get paid to be on time, not smart).
With discussions with my dealer he mentioned the deck design has lots to do with windrows, such as an open front vs closed.

Again, no wagering...

Bluegrass, Pick It Up!

 

[Bird]

Glenn, you'll notice I said <font color=blue>what windrowing is done</font color=blue> and it's very darned little, too. But I do know I get just a little more discharge to the left of center than to the right. As for the finish mower, yep, the blades on every one I've ever used turn clockwise; just the opposite from the brush hog (and I have no idea why). Even my rear discharge finish mower has the blades turning clockwise as viewed from the top.

Bird

 

[glennmac]

Well, as things now stand, we may have two different theories: the Bo theory and the Bird theory.

Assuming we have a CCW brush cutter, I think the Bo theory is that some of the cut grass gets carried past the left side, past the back, and then piles up on the right side when it contacts the uncut grass that is constantly entering the front of the cutter. The Bird theory seems to be that the cut grass tends to bunch against the first side it hits, the left side.

Now, if these theories apply to finish mowers, couldnt they be tested by looking at a rear discharge finish mower and seeing which side has a larger build up of clumped grass? Or are the dynamics of a three spindle finish mower too different to compare?

 

[TerryinMD]

I've only used a rotary cutter once. Couldn't even tell you the brand name as I borrowed it from a neighbor and it is just one big pile of rusted steel. I did not see any windrowing at all. I cut weeds, high grass, and brush and it just beat everything to a pulp. Had small piles of stuff in random areas.

I quickly scanned this thread and I did not see anyone mention anything about how sharp the blades might be. Is that a factor??

 

[Bird]

Glenn, my opinion is that this will not be completely resolved because we're talking in generic terms about "brush hogs" and some of them have decks that are shaped a little differently. On my Howse, the sides of the deck angle toward the rear, with the lower edge angling up toward the straight open section on the rear (and of course, I have homemade chain guards), while the newer Bush Hogs have a rounded rear deck and sides. And I never meant to imply that mine windrowed to the left; only that there's a little more to the left than to the right. Actually, most of the discharge is in the middle (most open part of the deck). As for the dynamics of the 3-spindle finish mower, there are some differences between brands under the deck, and of course, a side discharge deck is different from the rear discharge. My rear discharge mower has a rounded "baffle" on the right side, but not on the left side. I understand why, but doubt that I could explain it without "show and tell."

And being a pragmatist, I don't worry about all this deep thinking and theories; just does it work the way I want it to?/w3tcompact/icons/laugh.gif

Bird

 

[Rowski]

Glenn

Would ground speed have anything to do with it? It would seem that slower ground speed would result in less windrowing, maybe? Also could the "tip" (front higher, lower or level with rear) of the cutter have something to do with it? Maybe the right combination of them all could fix or reduce the windrow problem.

Derek

 

[glennmac]

There obviously can be a number of variables that affect material discharge. Another I thought of is the back of the cutter. Some have a solid shield, which would tend to keep material and air under the cutter. Some have chains, which would seem to be able to hold material but let swirling air escape easier. Finally, some people run with no shield or chains at all, just the large opening, which will discharge more material. I dont know how any of this would affect windrowing.

 

[MDNick]

At least theoretically, ALL brush hogs should rotate CCW. And it ain't got a thing to do with the brush hog. ALL PTO's rotate clockwise (save for that one Kubota, B6100???), when viewed from the back. And pretty much all brush hog gearboxes are nothing more than 2 bevel gears. So you get a direction change there, the brush hog will always turn CCW when viewed from the top. Unless the manufacturer opted to use a more complex gearbox, and there is no good reason to.

Farmer kid usetabe, Farmer Wannabe

 

[Rowski]

<font color=blue>As for the finish mower, yep, the blades on every one I've ever used turn clockwise; just the opposite from the brush hog (and I have no idea why). Even my rear discharge finish mower has the blades turning clockwise as viewed from the top.</font color=blue>

Bird this has been driving me crazy. I don't even own either of them. I found some parts diagrams of a rotary cutter and finisher mower gear boxes. The only difference in how the different direction is accomplished is by placement of the input bevel gear. After comparing the two diagrams and seeing the placement of the bevel gear I was still unsure. Now, no laughing.... I VISUALLY proved my point to myself by using axles and bevel gears on my Legos. Pretty sad a 29 year old is still playing legos. Attachment show it far better than I could ever explain.



Derek

 

[glennmac]

Derek, do your legos windrow in the left or right?

 

[TomP]

OK, here goes my two cents. The shape of the blade where the edge is, provides an airfoil, lifting the cuttings up into the chamber to be recut, by drawing air from outside the cutter inward(ie- a vacuum), yada yada yada. As the mower moves forward, the areas experiencing the greatest wind-swept area will be on the right and left sides. Additionally, the blade speed is highest at the circumference of the blade cutting circle. That should add to airflow, and keep cuttings suspended best on the outer edge of the blade, providing all other things are equal.

If you raise one edge(front, back, or either side), you reduce the vacuum, and cuttings drop there, or a little after that point of rotation. I think that's why the rear is supposed to be a little higher than the front. Using the same argument, if your left side is higher, you'll drop on the left.

Theoretically, since the center of the cutter has the least amount of vacuum(no edge, no blade, and no windspeed), the cuttings should dop on the center line(and out the back if it's raised).

One thought--on a CCW rotation, the right side isn't cut as well since your wheels just crushed the grass ahead of the mower. This ought to decrease the vacuum efficiency on that side--the grass isn't standing as tall as that immediately surrounding it. SO,.....maybe we should really have the right side lower by 1/2" to offset that.

What do you think? If you practice in front of a mirror, and can preach this with confidence, you might start to believe it. Seriously though, try it out and see if you can make the windrows shift or go away by changing the level front/back and left/right, and post your findings. After all, I'm just a pizza guy.

 

[Rowski]

Depends on how I dump the BIG box that they are in. But usually no. They need to be spread out evenly, to allow one to see and find the peices that one needs.

/w3tcompact/icons/smile.gif/w3tcompact/icons/smile.gif/w3tcompact/icons/smile.gif





Derek

 

[Bird]

Derek, I haven't gotten into that deep thinking yet on this topic./w3tcompact/icons/laugh.gif I don't know whether the gear boxes are different or not, but perhaps one consideration is the fact that you only have one spindle to turn with the brush hog; i.e., direct drive from the gearbox, while the finish mower has the direct drive out the bottom of the gearbox, then a belt to turn multiple spindles (blades). I've never thought about whether the belts reverse the direction or not. I guess it wouldn't be very difficult to remove the belt cover and see which way the output shaft turns on the finish mower (if I cared enough to do it/w3tcompact/icons/laugh.gif).

Bird

 

[theboman]

Upon a closer look I do stand corrected (a first time for everything...I'm single), my rotary cutter windrows to the left like everbody elses. I ain't too smart, just really good looking.

Speed causing the windrows? Nope. It's the sides of the rotary cutter. The grass/weeds etc builds up on the side and trails out the back of the cutter. It ain't no other way out.

Bluegrass, Pick It Up!