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sampler
01-16-2010, 11:01 AM
I have seen manufacturers blade tip speed ratings from 18,000 to 19,000 fpm.

Is that significant in how the mower cuts and the lawn looks after mowing?

topsites
01-16-2010, 11:26 AM
No, not really, at least not on a new mower, and I say I don't think so because they all say that,
way I see things it's meaningless technical jargon designed to make lookers go 'wow look' which
then that's supposed to make you reach for your wallet and start throwing money at them.

Which...
Did it work? :p

Odd, aren't the nerves of the eyes connected to the hand reaching for the wallet?

And it's not that all specifications are BS but this fps blade tip speed is certainly not one
of the specifications I care a whole lot about, as one might have gathered.

dbear
01-16-2010, 12:03 PM
Generally speaking, the faster the blade tip speed, the faster the unit's cutting ground speed. Something that seems to be important in this industry. So BTS is not entirely BS.

kenneth meals
01-16-2010, 12:16 PM
Blade tip speed has alot to do with the productivity of the mower and quality of cut. Also helps with to distribute clippings more evenly.

jkilov
01-16-2010, 12:27 PM
Like the guys said: higher blade tip speed allows acceptable cut quality and discharge at faster mower speed - equals better productivity. BTS is by no means a substitute for deck design.

Drawbacks: louder deck noise and poor fuel economy.

Lordtimothy
01-16-2010, 12:37 PM
Blade tip speed is also a safety thing. ANSI standards require all machines that are certified to be below a certain point. You also have European standards ect ect to follow if you want to sell in other countries.

Faster you spin the blades more chance of something going horribly wrong so that apparently was decided to be the safety threshold. Not just blades and items coming apart from the deck it also affect rocks and any item you hit.

More I think about it there maybe a point of diminishing returns on how fast the blade turns. But all in all one thing you can be certain of it is a safety thing. That is why it is limited to 18-19k. Protects the companies from lawsuits due to the industry accepted standard.

Timo

Valk
01-16-2010, 01:08 PM
Then there are certain conditions that require a lower BTS to perform the given task optimally. I've found leaf mulching to sometimes work best at reduced BTS/throttle...and also in certain moist grass situations.

There's only so many variables we have control over (clean deck - blade choice/sharpness - discharging/mulching/bagging - etc) and engine speed->effecting BTS is yet another.

As usual, your mileage WILL vary...but you'll never know if reduced BTS will be a benefit unless actually powering down & trying it.

mowerbrad
01-16-2010, 02:05 PM
Like others have said, the faster blade tip speed, the faster the unit can mow (ground speed wise). But you also need to look at the deck. Certain decks have higher capacities and can handle larger amounts of clippings than others can. Decks are designed with a blade tip speed in mind, so the tip speed and the deck are matched together to have the best performance out of the deck.

MikeKle
01-16-2010, 02:30 PM
Also not mentioned is the faster the blades are turning, the more suction/vacuum that is created, and that means less non-cut grass left behind.

Kutz Lawns
01-16-2010, 06:51 PM
You can also put smaller pullies on the spindles for a higher tip speed!

OH NO, not again!

MikeKle
01-16-2010, 09:34 PM
You can also put smaller pullies on the spindles for a higher tip speed!

OH NO, not again!

There is so many threads on this, has anyone ever actually tried installing smaller pulleys? I am curious if it will result in higher blade speed. In theory it should work, but who knows for sure?

NEWGUYRI
01-16-2010, 10:46 PM
is 17,300 fpm an acceptable speed?

dishboy
01-16-2010, 11:06 PM
is 17,300 fpm an acceptable speed?



NO! 17,305 is a minimum.

Kutz Lawns
01-16-2010, 11:39 PM
There is so many threads on this, has anyone ever actually tried installing smaller pulleys? I am curious if it will result in higher blade speed. In theory it should work, but who knows for sure?

Personally I've never tried it but thought about it but mine mows fine, stripes fine & performs fine, so why F__K with it! Just another added expense for no good reason!

I think most people on here who ask these type questions are just asking questions to ask questions and no real purpose & I think most are really just talking to themselves but it's no big deal, it's entertaining!

Don't take it the wrong way either, it's just MHO

Yea, it's winter!

Ooomwizard
01-26-2010, 02:03 AM
A while back I calculated tip speed to be around 200 mph at around 18k - 19k rpm, depending on blade length. I think govt. folks limit tip speed to under 200mph so that items being discharged will not be at a deathly velocity like a gun bullet.

Makes sense to me.

dbear
01-26-2010, 10:49 AM
A while back I calculated tip speed to be around 200 mph at around 18k - 19k rpm, depending on blade length. I think govt. folks limit tip speed to under 200mph so that items being discharged will not be at a deathly velocity like a gun bullet.

Makes sense to me.
I recall an episode of mythbusters (3 way ricochet) where I think they said something like a small projectile had to be a touch above 300mph to be lethal 100% of the time. If so, it stands to reason that what you say makes sense. Sure at 200mph it'll hurt like hell and probably break the skin, but it shouldn't kill you.

Maple Wood
01-26-2010, 10:57 AM
I was having trouble cutting a commercial property. It was weedy crab grass with a small infestation of fescue. They switched to every two weeks.

Any way I decided to see what more blade tip speed would do. I cranked the high idle stop up to 4200 rpm from 3600 rpm. MAN!!!!!!!! did my mower cut like an animal. It blew that crap 15-20 feet. I loved it, but was afraid what that would do to my engine. So....I turned it back down:cry: