Why are lawn tractors so slow?

[AuCivil]

Please don't take this as a malicious comment, but have you ever tried to mow at 12-13 mph?
My X739 does not have a speedo, but I rarely mow at top speed with it. At PTO rpm's the 3320 will easily do 12 mph, but I'd never consider that speed for mowing - especially without a seat belt to keep me in the cab.

No problem and you make a valid point. In reality, I don't want to mow at 13 mph but if the unit was able then it would cut that much better at 9 mph. I suspect that the X700 will not cut that well at the rated high speed of 8.5mph since it is being pushed to the limit.

 

[AuCivil]

I have owned 2 ferris ZTR,s and 1 Kubota 326 pro commercial model ZTR.I now own a JD X740 series (diesel)with commercial 7 iron 60 inch deck.This is my take,loved the ZTR but you will NEVER be able to mow at top speed unless you are on a rut/bump free lawn.How many times does that happen?I can tell you my X740 turns very sharp and maneuvers around my trees with ease almost as close as my ZTR did without the rear wheel spin ZTR,s have.

Why did you go tractor and will you go back to ZTR's?

 

[ovrszd]

I tend to agree with Kenny.

I think it's all about blade tip speed. I think the ZTR's blade speed is much faster than the tractor style.

As for stability, I ain't buyin that. I can haul butt across my lawn at max speed in high side with my JD2210 and cramp the wheel, it won't even lift a tire. Couldn't tip it over on a bet in flat ground conditions. Then if you talk hillsides, it will run circles around a ZTR.

 

[AuCivil]

I tend to agree with Kenny.

I think it's all about blade tip speed. I think the ZTR's blade speed is much faster than the tractor style.

I'm sure they spin the blades at the same speed if they wanted.

 

[ovrszd]

I'm sure they spin the blades at the same speed if they wanted.

What?? Missed your point?

Blade speed is all about ratios.

For example, my Son replaced the Onan engine in his old JD420 with a Honda V-twin. It turns a higher governed speed than the original engine. He mows as fast as it will run.

 

[coobie]

Why did you go tractor and will you go back to ZTR's?

Loved the ZTR,s when I was in a hurry to mow grass but thats pretty much all they will do efficiently.I am retired now(not in a hurry) and went back a true garden tractor that I can do more with,mowing,hauling garden carts,snow plowing,run a garden tiller and such.Never going back to a ZTR but they have there place.

 

[AuCivil]

What?? Missed your point?

Blade speed is all about ratios.

For example, my Son replaced the Onan engine in his old JD420 with a Honda V-twin. It turns a higher governed speed than the original engine. He mows as fast as it will run.

What I meant was they could gear the tractor PTO to spin the tractor blades at the same RPM as the ZTR. They could also increase the travel speed of the tractors. My question is - why do they choose not to?

 

[CinderSchnauzer]

No problem and you make a valid point. In reality, I don't want to mow at 13 mph but if the unit was able then it would cut that much better at 9 mph. I suspect that the X700 will not cut that well at the rated high speed of 8.5mph since it is being pushed to the limit.

As previously stated, I don't cut at full speed with my X739, but on my lawn, I think it actually gives a slightly better cut than the 7-Iron MMM on the 3320 and I think that is essentially the same deck used on many JD ZTR's. Anyway, whatever you decide - good luck and have fun.

 

[ovrszd]

Loved the ZTR,s when I was in a hurry to mow grass but thats pretty much all they will do efficiently.I am retired now(not in a hurry) and went back a true garden tractor that I can do more with,mowing,hauling garden carts,snow plowing,run a garden tiller and such.Never going back to a ZTR but they have there place.

That's my problem with them as well. I mow, push snow, blade the driveway, carry the BB, and haul wood in the tote box with my tractor. If all I wanted to do was mow on relatively flat ground it would be ZTR all the way.

 

[ovrszd]

What I meant was they could gear the tractor PTO to spin the tractor blades at the same RPM as the ZTR. They could also increase the travel speed of the tractors. My question is - why do they choose not to?

Not sure why they choose to run the blade tip speed slower. Not even positive they do. Just can't think of any reason the ZTR would cut at a faster speed other than a difference in blade tip speed. As to ground speed, my tractor runs faster than I can ride comfortably so more speed isn't necessary. Haven't looked at the specs, so can't say for sure how fast that is.

 

[jenkinsph]

No problem and you make a valid point. In reality, I don't want to mow at 13 mph but if the unit was able then it would cut that much better at 9 mph. I suspect that the X700 will not cut that well at the rated high speed of 8.5mph since it is being pushed to the limit.

My x749 will mow pretty well at top speed but my lawn is super smooth. In most cases I prefer to mow about 5 or 6 mph as I am not in that much of a hurry and would rather circle a tree much slower. Trim close to trees but not damage the bark, imo the 700 series is fast enough.

 

[Mach One]

At 8.5 MPH, the X7 is the fastest GT out there. Yes the ZT's go faster. My yard is golf course smooth, but I would never mow at top speed. The cut will suffer if you go fast. Besides, I'm not in that much of a hurry! I enjoy my seat-time.:thumbsup:

 

[KennyG]

I did a little more research and I'm probably not 100% on track on the blade tip speed explanation. Apparently there is a national standard that limits mower tip speeds to 19,000 fpm on commercial equipment and a little less on residential equipment. Our compact tractors, ZTRs and high end garden tractors probably have a 10 to 15% edge on the smaller machines which would probably improve the cut but not allow for a huge difference in mowing speed.

 

[LD1]

Apparently there is a national standard that limits mower tip speeds to 19,000 fpm on commercial equipment and a little less on residential equipment.

Never knew that.

I have often wondered why they didnt push it higher. Since 20 years ago a 3 +/- HP per foot was about what finish mowers ran. Now its not uncommon to see double that. Seems we have pleanty of power. I know my mower does. 27HP/61". But aside from rough ground, often times the speed limiting factor is not a very clean cut of stemmy things. Like Dandelion and what we call buckhorn. Seems a little more speed would help.

I have often though about slightly increasing the size of the deck drive pulley, or slightly decreasing the spindle pullies to get a tad more speed.

 

[timbatrader]

Here is a link to a high speed mower that you tow behind an ATV they claim 9mph but the finish is not lawn quality more intended for topping paddocks
Twin 1270 | New Zealand - Tow and Farm

 

[thecarman]

Take a look at a ferris 5100z.....shocks for suspension and 12mph.....best riding z on the planet....ive been on em all...jd, kubota, bad boy....and none of them compares, like messmaker said, you have to be on a golf course to mow top speed...but not on a ferris!

 

[ray66v]

I have always been told riding mower speeds are limited under federal regulations. Riding mowers have their speed capped at like 7mph.

The same people gave us the interlock that makes the mower shut off, if you back up.

Real zero turn mowers, are actually commercial products, so they are exempted from these regulations.

I will see if I can find any documents pertaining to this.

 

[ray66v]

ANSI sets the standards.

This site has the documents, but it's a pay to view.

OPEI: Standards Listing

There are definitely different standards listed there for Commercial vs Consumer products.

 

[DK35vince]

I mow a 7+ acre lawn.
My Wheel Horse garden tractor is rough riding and I wouldn't want to try to mow our entire lawn with it, it would likely take an entire day to mow the lawn.
My 35 HP compact tractor with an 84" finish mower rides better, but trying to mow over 5-6 MPH gets really rough. (takes just over 3 hours to mow the lawn)
I can mow the same lawn with a 35 HP Hustler Super Z zero turn w/ 72" deck in 2 hours. With the flex forks, suspension seat and 7-8 PSI tire pressure the ride is MUCH better than the tractors.
The rough areas I have to slow down, but much of our lawn I can mow at full speed (13-14 MPH).
With the better ride ,better maneuverability and much higher mowing speeds, my Super Z zero turn will mow circles around the tractors.

 

[PILOON]

Besides industry standards to attain speed you would need different gear ratios.
The kind of ratio needed for speed would also require more HP which in turn would increase prices and consume more fuel.
Since mowing is site related and road travel is not in the picture speed is not essential.

Were mowers meant to road travel then wheels would need to be larger, engines more powerful resulting in a fast heavy mower that would damage lawns.
And that is not counting all items to conform with road laws. (lights, turn indicators etc etc.)