Blade speed

Discussion in 'eXmark' started by Vibe Ray, May 26, 2002.

  1. Vibe Ray

    Vibe Ray LawnSite Senior Member
    Posts: 785

    From what I know, the fastest legal blade speed 4 a lawn mower is 19,000fpm, right? Then why are eXmark mowers only 18,500fpm and not 19,000fpm? Is there any reason? Thanx!
     
  2. awm

    awm LawnSite Gold Member
    Posts: 3,354

    dont know the answer from exmarks .
    but if my lazer runs 3600 rpm and puts out 18500 bladespeed. then i turn the kohler up to 3750 or 3800,,which i do.
    probably getting that 19000.
    long as it cuts good and the motor likes ithat rpm ,and it does. thats all that maters to me.
     
  3. awm

    awm LawnSite Gold Member
    Posts: 3,354

    u exmark guys gotta get over that memorial day weekend,:) went to the race huh, whew ,i been theire. now i watch it on the tele..
     
  4. TLS

    TLS LawnSite Fanatic
    Posts: 7,937

    Vibe Ray,

    Just wanted to chime in here.

    Where is it written that 19,000 fpm is the "highest legal speed"? I could never find it at OPEI, ANSI, OSHA, etc. So seriously, if you know where this is stated, then let me know.

    Another variable is engine speed (RPM). I will assume that Exmark quotes their blade tip speed at 3600 RPM's. My LC Lazer runs at 3760 RPM's free load, so how much over that "magic" speed are my blades!?

    All I know is that this Lazer is the BEST cutting deck out there. I've tried many of the rest, now I have the best! :D
     
  5. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    Vibe Ray,

    Here is the reason for this, itÂ’s all about safety and meeting the Standard. Blade tip speed is factored by engine rpm, pulley size and angle of V groove, and blade length. The short version of this is, how fast is your spindle turning and how long is the blade determines blade tip speed.

    By keeping our blade tip speed slightly lower than spec it gives us some breathing room. An example of where this can make difference is if the belt seats into the deck pulleys further than it does on the engine. Also if a person jacks up his engine RPM it will change his blade tip speed. An after market or the incorrect belt could also change this if the conditions were right.

    When it all comes down to it there are many factors that cause this to vary so we play it on the safe side. Until the Standard changes we will remain a little on the low side.

    Thanks, Fred.
     
  6. TALLEY-HOE

    TALLEY-HOE Guest
    Posts: 0

    ALTERING MFG. CONDITIONS IS A BIG--NO! NO! IF YOU DON'T BELIEVE ME JUST ASK YOUR FREINDLY INSURANCE REP. THEY MAY NOT PAY OFF IF THERE IS AN ACCIDENT. YOUR BEST BET IS TO THINK-----SAFETY ALONG WITH PRODUCTIVITY.
     
  7. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    TLS:

    You were asking where it was specifically stated that 19,000 fpm was the highest legal blade tip speed, so here ya go.

    In section 8.1.4 - Blade tip speed - of the ANSI/OPEI B71.4-1999 Safety Specifications for Commercial Turf Care Equipment, it states that "the maximum tip speed of any blade shall be 19 000 ft/min."

    I just wanted to make sure that we were all on the same page. ;)

    Hope this helps,

    Dustin
    Exmark Customer Support
     
  8. TLS

    TLS LawnSite Fanatic
    Posts: 7,937

    Thanks Dustin!

    I really thought that it was just a manufacturer (DC bragging gimmick) type thing.
    In the past I was up, down, and all around the ANSI site and could find nothing about lawnmower blades, etc.

    Sorry to make you have to post just for my "Doubting Thomas" curiosity!

    Thanks Again
     

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