# What's my ground speed please?

Discussion in 'eXmark' started by justmjc, Feb 21, 2004.

1. ### justmjcLawnSite Senior Memberfrom michiganPosts: 261

I have a 2003 20hp kohler 52" lazer z and I'd like to know my mph. I believe I can go up to 8 mph but can someone verify that?

After looking at exmarks charts, it claims my unit at 8 mph can cut 3.36 acres / hour at that rate at 80% efficiency. Are most people achieving 80% efficiency rates or better, or are you falling a bit short?

2. ### eXmarkManufacturer / SponsorPosts: 4,258

justmjc,

The 52" Lazer HP has a top speed of 9.5 mph in 03.

The 100% efficiency does not take into account the "real world" product of the mower.

The 80% efficiency takes into account things like overlapping of cuts and the time it takes to maneuver the machine through turns etc. at any given speed.

Thanks,

Terry

3. ### RogerLawnSite Fanaticfrom McMurray, PAPosts: 5,930

One way is as follows (I'm open to other ideas):

1. Mark off the distance traveled in 20 seconds.

2. Count the number of yards (3 ft steps). If you are walking behind a mower, just count the number of 3 ft steps you take in 20 seconds. Be sure your step is 36". If you are on a rider, then mark the "start" and "end" points for 20 seconds of travel, then determine the distance and get the number of yards (3 ft steps).

3. The mph is the number of yards (3 ft steps) divided by 10.

By example, if you are using a hand mower and count the number of 3 ft steps you take in 20 seconds as 35. The speed is 3.5 mph.

This is very simple. Yes, I know for the purist, the units don't work. I think the actual time to make the numbers exact is something like 20.23 seconds. I'll spare everybody the torture of the math to show how it works, but will share it if somebody asks. I worked it out a couple of times in past years, but suppose my brain will still work well enough to do it again.

BTW, this was published in a John Deere farmer's handbook. I remember seeing it in the early 50s. Does JD still publish an annual booklet to give to their farmer customers? Maybe the formula is still given in that handbook.

4. ### HankAndSuziLawnSite Memberfrom 7Posts: 4

I think you can tow a big rope with knots tied in it...nevermind.

5. ### eXmarkManufacturer / SponsorPosts: 4,258

Guys,

When in doubt buy a new tool/toy.........a good GPS could do the job. I wonder if I can pass that off as a business expense?

Terry

6. ### Hawkeye5LawnSite Senior Memberfrom Hendersonville, TNPosts: 295

I deducted the cost of my GPS (Garmin Etrex) . It will make area measurments so I use it to obtain the total square feet in a yard. Just access the correct program, pust start, walk the boundry of the yard, when you return to the starting point push stop and there it is. No more fumbling with a clip board and measuring wheel.

7. ### smplayer85LawnSite Memberfrom Indianapolis, INPosts: 2

who cares?? ZTRs go faster than any other mower...so why are you complaining?

8. ### RogerLawnSite Fanaticfrom McMurray, PAPosts: 5,930

Sorry to create a stir ... I thought I might be of help.

The best solution for determining speed: Distance traveled, divided by the time to travel the distance. Any elementary school student can do this calculation.

I wonder how many of the postings about "how fast I mow" have much credibility. I read of mowing at 7, 8, 9, 10 mph. Nobody ever says how they know their mowing speed, how they have calculated/determined the speed. Most such claims of these mowing speeds probably can be discarded.