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Hi all,
Does anyone know the blade tip speeds for the popular tractors/decks?
I would really like to know mine - x540 with 48" edge deck.:fing32:

I had a commercial walk behind mower and it's big advantage was the speed of the blades. It made for a really nice and clean cut. My rider is good but not quite...is that the reason?

:thanku:
 

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I was wondering that too. I thought I saw the 60" 7-iron deck bragging about faster blade speeds, but I'm not sure if that's true; might have been the 7-iron for another platform.
 

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Enginerd - DieselDork
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I think there could be another reason: smaller front wheels.

I've found that with my particular grass, it tends to lay over under the front wheels and so wherever my front wheels go, the grass is slightly taller there.

Now that the grass is very dry, it stands up quicker and the quality of the cut is much better.

Just a thought.

I'm thinking about converting to a single 10" bicycle wheel in the front to see if that helps.
 

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I believe it is 200mph there is pulleys that can increase it to around 220mph.
 

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http://www.lsuagcenter.com/en/lawn_garden/commercial_horticulture/equipment/ZTR+Mowers/Safety+Standards+for+Commercialsize+Riding+Mowers.htm

19,000 feet per minute is the commercial top end, and I think 18,000 fpm is the residential limit. Both set by ANSI. This would be @ 200mph as sircharles stated.

Blade tip speed is only one factor in cut quality, and it's not a given that a higher blade tip speed will equal a faster or better cut. I know the JD ZTR's only recently went to advertising the 18,000 fpm speed, but they cut no better or faster than the older one's with lower speeds (I think @ 16,000 fpm). We were told they changed the speed strictly so they could advertise it, as other companies do. JD previously did not call this out as a spec.

Last I saw, most JD residential decks were in the 16,000 to 17,000 fpm range.

Make sure you deck is properly leveled, blades are sharpened correctly, and you are running at full throttle. If you are still having problems, there may be other blades available that could help (low lift, high lift, mulch, etc). I forget what's available for the 48C/Edge though. That's normally a very good cutting deck.
 

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I was wondering that too. I thought I saw the 60" 7-iron deck bragging about faster blade speeds, but I'm not sure if that's true; might have been the 7-iron for another platform.
It's kind of misleading.

Blade speed and blade tip speed are TWO different things.

I think I'm correct when I say all Mowers run at the same RPM, or at least the PTO is the same RPM.. and blade speeds should be the same.. given the same gearing to the blade spindles.

NOW the longer the blades the faster the balde tips have to move to get around the circle...

For example.. You have a blade that runs at 10 RPM (I know inconceivably slow but makes the math easier).. so measure out an inch from center.. the circumference at that point is 6.28 *10 (RPM) a blade two inches long would travel 62.8 inches a minute.

Go out another inch.. 2 inch radius (4 inch Diameter) you now have a circumference of 12.56 or a blade tip that would travel 125.6 inches a minute.. TWICE as fast as the one inch blades.

The longer the blade the faster the blade tips move even though the rotor is turning at the same RPM..

This is why you get the WHOP WHOP WHOP sound on the two blade Huey Helicopter (blades are so long the blade tips break the sound barrier) and the four bladed HUEY with MUCH shorter blades does not have the WHOP WHOP WHOP sound even if they are rotating at the same hub speeds/ RPM

So if your lawnmower has three blades to cover 48 inch mow width they would have a much faster tip speed than if you had four blades covering the same 48 inch width.
 

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SO if you replace a 22" blade on any given tractor with another 22" blade.. the blade tip speed is limited by the RPM of the mower deck, and HP of the Tractor.

If they say they have the fastest mowing 22" blade they are full of BS. The only way to increase blade speed would be to increase the RPM of the mower deck, OR using longer blades.. and try fitting a 24" blade on a deck made for 22" blades..
 

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So why is ANSI's residential use 1K less than commercial? How much difference could that possibly make for whatever reason it's so. I could use that extra speed for my cutting and so could a bunch of others. It sure wouldn't strain my 20hp. Kawi one bit. Could it be a "Noise Thing" I wonder...
 

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I think there could be another reason: smaller front wheels.

I've found that with my particular grass, it tends to lay over under the front wheels and so wherever my front wheels go, the grass is slightly taller there.

Now that the grass is very dry, it stands up quicker and the quality of the cut is much better.

Just a thought.

I'm thinking about converting to a single 10" bicycle wheel in the front to see if that helps.
seems like is that case a high lift blade would be of importance, pulling up the grass then cutting it off...
 

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I've found that with my particular grass, it tends to lay over under the front wheels and so wherever my front wheels go, the grass is slightly taller there.
I've studied this issue for some time and drew the conclusion that only the left front tire comes back proud. The right front doesn't. Why? Direction of blade rotation.

The nap of the grass is in the direction of travel and the left blade outer edge also rotates in the direction of travel. The right blade outer edge however is rotating counter to the direction of travel and stands the nap back up, cutting it shorter.


I'm thinking about converting to a single 10" bicycle wheel in the front to see if that helps.
Narrower tires would result in more pounds per sq. in. of weight on the front resulting in the grass being pressed down harder. You would have narrower strips standing proud or narrow strips that are still bent over the next time you mow. What is needed is wider tires to float the weight reduing the PSI.

Higher lift blades might help as might higher RPMs. I increased my engine RPM and it improved the quality of cut.
 

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Enginerd - DieselDork
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Narrower tires would result in more pounds per sq. in. of weight on the front resulting in the grass being pressed down harder. You would have narrower strips standing proud or narrow strips that are still bent over the next time you mow. What is needed is wider tires to float the weight reduing the PSI.

Higher lift blades might help as might higher RPMs. I increased my engine RPM and it improved the quality of cut.
I was joking about the bike wheel, but thanks! :^)

I haven't found a Gator Blade equivalent for the star-lock blades on my 54" deck. I thought I heard someone say that they don't make blades for decks where they can't show any improvement over the original blades. I *think* that these are already hi-lift mulching/bagging blades. I already mow at full speed, so no gains (other than pulley changes) available there.

In my case, the real improvements will come from getting my yard to a full rye/bluegrass/fescue mix, instead of yellow nutsedge, crabgrass, and clover. :^(
 

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When you compare the finish cut of a commercial ZTR (C-ZTR) against that of a residential mower (R-mower), no matter if it's a mid mount or rear mount the commercial will produce a faster better finish cut every time. This can mainly be evidenced by the stripeing effect. A C-ZTR can produce highly visable stripes via the speed of the blade tips only whereas the best of the R-mowers needs a roller or other device to physically lay the grass in certain directions to get the same effect.
IMHO thats proof that blade tip speed directly influences lift and the faster the speed and better the lift.
Anotehr example, you can put the same blades on either and the C-ZTR will produce higher lift as evidenced by the finish cut quality.

re. tire compaction, although this may sound incorrect, the larger the area of the tire that contacts the ground, the less weight is applied per square inch. With this in mind those large turf tires should, in theory be easier on the grass than slinny tri ribs or those small front tires found on C-ZTR's.
Also notice that most C-ZTR's have large rear wheels, similar or even larger than most R-mowers, with most of it's weight is centered over these tires and these tires generally run over and compact the grass after the cut. It would seem that this would make two large depression in the finish cut but if you watch one in action, usually theres no depressions, and if the operator is mowing to produce stripes you'll notice that the finish product immediately after his pass looks like a nice and even cut.
So, in conclusion, I offer that higher blade tip speeds will produce higher lift which will produce a better finish cut.
JMHO :D
Dave
 

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Before I purchased my '09 X324, I asked JD engineering what the blade tip speed is (dealer didn't have a clue)...they stated 17,000 fpm. mowing commercially in the past, this info was important to me as I know first hand what 18,000 fpm and a set of high lift blades can do for quality of cut. When I got in the market for a lawn tractor, I was surprised that JD didn't make known their blade tip speeds.
 

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I've been in the industry for a long time...and I know that the only folks that publish blade tip speed are companies that hit the ANSI limit on purpose. Most do this strictly to have a spec in their brochure, regardless of whether it makes their decks cut better. JD ended up having to up their speed a few years ago strictly because folks kept asking and they wanted it in the specs. Ask anyone, the old 7-Iron decks cut just as fast as the later 19,000 fpm decks - but used less HP doing so.

As I said earlier, BTS is not only factor in good cut quality, and JD designs the decks as a unit, and uses whatever BTS gives a quality cut...and that may not be at the top limit speed. Plus there is no need to burn horsepower and fuel to simply spin the blades faster than they need to go.
 

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As I said earlier, BTS is not only factor in good cut quality, and JD designs the decks as a unit, and uses whatever BTS gives a quality cut...
Sounds like you know your JD mower decks... Why would my JD 48C/'04 GX335 cut/mulch/bag so much better in reverse? It's set up to spec, it's WOT all the time and blades are kept sharp. Just wonderin' if I got the deck on backwards... (wish I could!:))
 

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Sounds like you know your JD mower decks... Why would my JD 48C/'04 GX335 cut/mulch/bag so much better in reverse? It's set up to spec, it's WOT all the time and blades are kept sharp. Just wonderin' if I got the deck on backwards... (wish I could!:))
How is your deck level set? You might be raked too low in the front, which is mashing the grass down more than usual. This will limit airflow up the bagger and will keep the grass from being pulled up and cut as cleanly as it should. I have seen rare instances where a reverse rake in the deck (1/8-1/4" higher in the front) gives a better cut sometimes. Grass is weird stuff at times, and how a deck performs can vary across the season due to internal grass moisture, cut height, growth rate, etc.
 

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All of my tractors are pre 1992 John Deere and the cut quaility is awesome. My experience has been that a high lift blade (I like Gators) works the best. I also think I remember reading that the blade tip speed was lowered for residential use at some time due to safety reasons. Is this true? Adam
 

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I reset my deck last week with 1/8" forward rake as the book sez... Cut yesterday first time and it's really even and cutting clean (w/Gators). My observations about the air flow started when handling leaves/spruce needles on the driveway. If I back up over them the PowerFlo will bag them just fine. Going forward most of them will just scatter.

The dealer had installed a little "lip thing" back of the front edge of the deck, not the bigger "anti blowout kit" for doing leaves, but a thinner one. I'd hate to think what it would be like without it. When I get ready to grind up my leaves I attach a piece of 1¼ pvc well line under the right front lip of the deck. This holds back most of the leaf chips and I get a far better result.

My observation is that way more air is entering the back of the deck than the front, and the excess that doesn't go out the chute goes out under the front right side of the deck. Clean bagging on pavement, you gotta go backwards. I'll bet this deck mounted backwards would be as good a cut as any mower can get.
 

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\ I also think I remember reading that the blade tip speed was lowered for residential use at some time due to safety reasons. Is this true? Adam
I am trying to find this answer too. Just curiosity.

The blade tip speed is limited to 19,000 feet per minute by American National Standards Institute (ANSI). But it does not differentiate between Commercial vs Resident
 

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JD used to set the blade tip speed to whatever worked best for the decks. This was residential or commercial. Everything cut great, and the commercial 7-irons mowed as fast as anyone else. Problem was, competitors would advertise being at the fpm limit just to have a cool spec to brag about (even if they cut like crap, "faster is better" right?). So, JD upped the commercial decks to 18,000 fpm for comparison purposes. Cut quality was still good, but fuel economy and power went down, sound went up. But hey, they could advertise the magic 18,000 fpm now. :banghead3

For residential mowers, JD still doesn't publish the spec. It's fast enough.

Go mow with it. Proof is in the pudding. Don't get hung up on the blade tip speed thing.
 
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