Rotary Cutter Rotary Cutter vs Finishing mower

[Fast Eddie]

I have been looking for a finishing mower for my JD 790, and I just saw a few posts talking about rotary cutters. Can someone explain the difference? My application is to cut grass on a 7.5 acre yard.

Fast Eddie

 

[howierd3866]

most finish mower have four wheels and belt driven not the best for tall grass. rotary mower also call bush hog usely have 2 wheels on the back and shaft driven very good on tall grass.

 

[Willl]

RCs are a rough cut, field type of mower. Even do small trees and brush.

FMs are for lawns and such, a much finer cut. Don't do trees or brush to well.

 

[MarkV]

The other thing is that a finish mower needs less power so you can run a larger mower. With 7.5 acres of finish grass I would want the largest mower my tractor would handle.

MarkV

 

[GE222]

A rotary cutter "bush hog" usually has a single heavy gear box, with a pair of heavy blades (3/8"-1/2" thick), and is used for mowing thick tall weeds and small brush along roadways, etc. It is either three point mounted, or pulled on the drawbar. The cut is effective but rough.

A finish mower is very similar to a belly mower on a garden tractor, having multiple spindles and lighter blades (3/16" -1/4" thick), except that it is mounted behind the tractor on its three point hitch. It is primarily used for mowing larger grassy areas, such as ball diamonds, etc. Smooth even cut.

Both types are available as bat-wing style, but that is a whole other topic.

 

[jinman]

Just a couple more differences:

1. Blade speed: The finish mower is made to operate at a much higher rpm than the rotary cutter. This enables the blades to do a more complete cut of the grass rather than ripping and shredding.

2. Grass Height: Finish mowers do best on thick low grass like lawns. They would normally be used much more frequently (probably weekly) to keep a very neat and trimmed appearance. Rough cut rotary cutters are designed to be used maybe once or twice a season to keep down noxious weeds and brush. That's the kind of mowing you normally see on the highway right-of-ways. So, the quality of cut and frequency of cutting would be a lot less with a rotary cutter.

3. Vacuum Lift: Rough cut mowers don't have nearly the vacuum lift as do finish mowers. Therefore, thicker grass is sometimes beat down rather than cut by the slower moving and duller blades of the rough cut mower.

4: Flail mower: Somewhere between the rough cut rotary mower and a finish mower is the flail mower. It's appearance is much like a rotary tiller on the back of a tractor, but it has many small blades that rotate at high speed and can cut grass almost to finish mower quality. You can maneuver with a flail mower about the same as with a rear finish mower.

 

[Ken45101]

One of the major differences is that a rotary cutter (brush mower/ "bush hog") has the blades mounted to swing back if they hit an obstruction (big rock, log, hidden concrete block, etc.) Finish mower blade are solid mounted and can be damaged (bent blade or shaft) if they hit something solid.

To put it another way, a guy once told me that a brush mower would cut anything I could drive the tractor over (small trees, etc.). He was wrong: there I things that I will not drive the tractor over, I back the brush mower over them ;-)

Ken

 

[herd]

Good explanations, could someone also explain how the RC w/stump jumper works, does it really jump stumps w/o damage to the gearbox and what size stumps will it jump. Newbie here w/Hardee 6' RC and JD 5203.

 

[Ken45101]

Stump jumpers work by allowing the shaft to slide up and over a stump. Think of what would happen if a straight shaft ran into a stump a 4 mph! The stump jumper has sloped edges and protects the shaft.

I once lifted a mower over a stump, but let it down too fast, before the mower was clear. It broke the blade in half! Made for a very unbalanced mower! Of course, a stump jumper wouldn't have helped in that situation.

 

[have_blue]

Here's what I have learned about finish mowers from my experience using both bush hogs and finish mowers.

Advantages

Slightly smoother cut. Sometimes it's not even noticeable.
Usually can cut grass shorter, to 1" or even less.
A given tractor can pull a 1-2 foot wider finish mower than bush hog


Disadvantages

Slower mowing speed for a given grass height.
Can't cut heavy grass or weeds if you're late mowing
More maintenance, belt adjustment, belt replacement
Not as rugged if you hit an object.
Wheels can be a problem. They can be damaged by hitting ditches, and axles can tangle with grass.