Mowing Mowing Speed

Frank_Nye · Nov 23, 2004

I am looking to buy a new mower and am curious about what you all think a good speed is to mow at.

My Kubota 1992 G2000-S is rated at having a top speed of around 9 MPH and sometimes I do have it floored (I mow about 6 acres) when I'm mowing.

I am looking to replace my tractor with a new one and have been looking at Deere, Simplicity, Cub and Kubota. Kubota has a new series coming out, the GR-2100 with a 21-hp diesel but it is only rated as having a top speed of 6.2 MPH and only comes with a 54 inch deck.

I can currently mow at up to 9 MPH with a 60 inch deck, although I don't think I really mow that fast most of the time. How fast do most of you think that you mow? My brother has a John Deere 335 and it is rated at a top speed of 7 MPH and when I have used his, I didn't seem to think it was slow.

Thanks for any opinions you all can provide.

Frank Nye

Nasty135 · Nov 23, 2004

Frank_Nye, Welcome to TBN Frank Mowing speed is a somewhat relative issue pertaining to ground condition and grass height or obstacles... In some of my cutting area ,I can go to Hi range which probably 5-7 Mph and it mows fine but in other areas that is too fast so I have go to low range and that is dreadfully slow...
Thats why I think I'm going to go to a ZTR for mowing...

But back to your question ,IMO if your used to mowing at speeds up to 7-9 and you get something smaller and slower that would not = Happiness unless you like seat time...
I mow as fast as I comfortably can /forums/images/graemlins/cool.gif

johndeere2210 · Nov 23, 2004

Mowing speed is directly proportional to the length of the wifes honey do list. The longer the list, the slower the tractor goes.

bczoom · Nov 23, 2004

Frank,

Welcome to TBN.

Besides mowing, what else do you need the tractor for?
Where I'm going with this is that for mowing, you won't believe how much faster a ZTR is over a tractor. I was using a Simplicity garden tractor and switched to a ZTR this spring. My mowing time was cut in less than 1/2. /forums/images/graemlins/grin.gif

Bob_Skurka · Nov 23, 2004

Frank, as others have said the absolute speed is not always the real issue. I mow with 2 tractors at home and recently semi-retired my Cub Cadet to mow my office area. Much of my mowing at home is now done with a Ventrac 3000 & a 52" deck, some is done with a New Holland TC24D with a 60" deck.

What I have found is the New Holland with the 60" deck has the fastest ground speed but is the slowest tractor to mow with because of its size and turning radius.

The Cub Cadet, had a deck that I think was 56" and it mowed slightly faster than the New Holland.

The Ventrac 3000 has the smallest deck and the slowest top speed, and yet it is by far the fastest mowing tractor I have ever owned. In fact it mows our 4+ acres of grass in at least 60 minutes less than the Cub Cadet.

A ZTR would THEORETICALLY mow even faster, but my "lawn" is really a bumpy hilly tree filled conglomeration of land that would rattle your fillings out if you tried to mow it with a ZTR. In fact the guy up the road bought a ZTR to mow about 3 acres, he finds he has to run it at about 1/2 speed because his lawn is reclaimed pasture and bean field and just too rough to run the mower the way it was designed to be run. I gave a ZTR to a guy I work with as a gift, he replaced an aging JD lawn tractor. He told me that his mowing time was reduced by 2/3 and he can finish his yard in just under an hour. He also said the main reason is not faster top speed, but the ability turn and maneuver so much faster that the tractor wastes no time/space.

So the lesson I learned was finding the right machine to run as fast as possible on the terrain I have. The Ventrac 3000 was my solution, it handles hills so steep that conventional tractors spin their wheels just trying to climb, it turns nearly as tight as a ZTR, and its articulated & oscillating body absorbs bumps and contours without scalping the turf. I can take corners at full speed on open ground and spin circles around shrubs and planting beds that the other tractors could not do.

Many people would find no need for something like my Ventrac and I am not advocating the brand, but using it as an example to show how the right machine is not always the one with the largest deck or the fastest ground speed. In my case the fastest mowing machine is the one with the slowest top speed and smallest deck . . . but if I could fit in into my garage, I would have loved to have gotten the optional larger mowing deck to cut even faster.

ThistleKop · Nov 23, 2004

Frank,
The "right" mowing speed is unique to you, your conditions and circumstances. If you're mowing 6 acres on a regular basis, you're the pro. I mow 2 acres of lawn and clip 50 + acres of pasture. I know when I'm being shaken too hard and the quality of cut that I'm getting is not acceptable. On the other hand, if you're looking for opinions about equipment, you've come to the right place!

TK

keeney · Nov 23, 2004

If quality of cut is important, 7 to 9 mph sounds too fast to me. The slower you go, the more chances the blade has to pull the grass vertical and cut it at a nice uniform height.

My JD 4100 with 60" is rated to cut 2.5 acres per hour, but my actual productivity is about 1 acre per hour on property that doesn't have than many obstacles. They must rate it at max speed or something.

- Rick

Gatorboy · Nov 23, 2004

They must rate it at max speed or something 

It's calculated using some speed -- not sure max speed -- but it is not considering overlap, re-tracing areas, etc. that you do when you cut. The number of acres per hour is determined from getting the full amount of cut constantly at some speed. Some may give you the max output along with a number based on 80% efficiency ... even that figure is hard to achieve.

Soundguy · Nov 23, 2004

I think I'm mowing at 10.5mph.. or a tad higher..

Soundguy

bczoom · Nov 23, 2004

( If quality of cut is important, 7 to 9 mph sounds too fast to me. The slower you go, the more chances the blade has to pull the grass vertical and cut it at a nice uniform height. )

Rick,

If the blades can keep up, that's not too fast. My ZTR blade tips are rotating at 19000 feet/minute. If my math is correct, that's about 215 MPH. That's enough rotations to lift and cut several times before I can travel over it, even at 10 MPH.

Brian

Freds · Nov 23, 2004

I have a G2160 and normally mow just about pedal to the metal, or rubber mat in this case. Sometimes it's floored. If you can handle the bumps and the mowed grass looks OK when you look back, then I'd mow as fast as you want to get done.

keeney · Nov 23, 2004

RE: "...and the mowed grass looks OK when you look back, then I'd mow as fast as you want to get done. "

But the next day when the grass that was merely squished over by the wheels and not cut to correct height recovers, stands up straight again, and is longer than the other grass, it may not look as good as when it was first cut.

I also seem to recall that mowers are limited to a maximum blade tip speed dictated by ANSI safety requirements (at least those marketed for residential use and claiming to adhere to such standards), so there is a maximum speed.

I think the "loft" of the blade may have a lot to do with things as well. A higher loft blade creates more airflow to stand the grass up and clear the clippings, but it requires more power for the same size blade and speed to blow all that air.

- Rick

ThistleKop · Nov 23, 2004

Rick,

 I also seem to recall that mowers are limited to a maximum blade tip speed dictated by ANSI safety requirements (at least those marketed for residential use and claiming to adhere to such standards), 

You're correct Rick. That max blade tip speed is 19000fpm as indicated by another poster. It is more than a optional std. CPSC insists upon it!

TK

keeney · Nov 24, 2004

19,000 FPM may seem really fast, but some arithmetic can put things into perspective as to why 10 MPH is pretty fast for mowing:

19,000 FPM tip speed on a 20" dia. blade is just a hair over 3600 RPM.

10 MPH is 880 feet per minute.

3600/880 is less than 4.2 revolutions of the blade per foot of travel.

You have both ends of the blade, and you cut on the front and back side of the deck, so thats 4 cuts per revolution, or 16.5 cuts per foot of travel (through the center-line of the deck to keep things simple).

Each cut is 12/16.5" or close to 3/4 of an inch apart.

Only the end 3 inches or so of the blade does the cutting, so 3 / (12/16.5) = just over 4 cuts on average for each blade of grass.

At 5 MPH instead of 10, you have twice as many revs per foot of travel or about 8 whacks at each blade of grass. At 2.5 MPH (walk-behind speeds), you are double that again, or 16 whacks at each blade of grass.

Things get worse with larger diameter blades because to stay at the same maximum FPM at the tip, the RPM has to go down.

- Rick

GerardC · Nov 24, 2004

( Mowing speed is directly proportional to the length of the wifes honey do list. The longer the list, the slower the tractor goes. )

LMAO! Gerard

keeney · Nov 24, 2004

RE: Mowing speed is directly proportional to the length of the wifes honey do list. The longer the list, the slower the tractor goes.

What about when mowing is ON the list?

- Rick

Soundguy · Nov 24, 2004

( You have both ends of the blade, and you cut on the front and back side of the deck, so thats 4 cuts per revolution, or 16.5 cuts per foot of travel (through the center-line of the deck to keep things simple).

Each cut is 12/16.5" or close to 3/4 of an inch apart.

Only the end 3 inches or so of the blade does the cutting, so 3 / (12/16.5) = just over 4 cuts on average for each blade of grass.
)

Regaurdless of how it may loo to you on paper.. I can tell you.. I mow at 10mph.. and there ain't nothing left to stand back up the next day that the mower runs over. I mow 10ac of my pasture every month.. I chop it off at 4" to 6" or so.

That's 5th gear on my tractor ( 1st and high ) and that was the recomended speed to cut with as told to me by the NH dealer.. In fact.. that was the selling point.. I wanted a machine I could cut fast with. I've seen other largeish tractors cut at that speed as well.

I'd guess 'what' you are cutting may have a little to do with it. Soft lush grass that can't support it's own weight and is already laying over may be an issue. Stemmy stuff, black tops.. weeds, etc cut just fine on my property.

Soundguy

keeney · Nov 24, 2004

RE: "I'd guess 'what' you are cutting may have a little to do with it. Soft lush grass that can't support it's own weight and is already laying over may be an issue. Stemmy stuff, black tops.. weeds, etc cut just fine on my property."

Yes, I was thinking lush lawn/park vs. pasture cutting.

Sufficient power and blade loft can improve things at higher speeds

- Rick

Dargo · Nov 24, 2004

Since my Kubota L5030HSTC has a digital speedometer in the dash, I can say that, depending upon the conditions, I mow at speeds from anywhere from 4.3 mph to about 11 mph. The slow area is due to the terrain being less than smooth. Perhaps with a good kidney belt I could mow it faster, but it wouldn't be fun. The performance of the cut seems to be the same independent of the speed I'd travelled. Of course, if I am trying to cut 10" off of the grass, I'd have to slow down or it would suffer. /forums/images/graemlins/blush.gif

Soundguy · Nov 27, 2004

( Of course, if I am trying to cut 10" off of the grass, I'd have to slow down or it would suffer )

I'd agree with that. Straight tall soft grasses seem to be the most difficult to cut well.. both due to height and coarseness of the plant.

I've found that plain old 'brush' is the easiest to cut. Bramble.. tall stemmy weeds like dog fennel and ragweed, etc. Pretty much as fast as you can safely drive through them you can cut them. When i bought my pasture it was about 7' tall.. but cut easier than my neighbors overgrown lawn that was 3' grass.

Soundguy