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Gravely @ 7.8/hr v.s. Ferris @ 5.1/hr ...

Discussion in 'Starting a Lawn Care Business' started by CP Estates, Mar 3, 2006.

  1. CP Estates

    CP Estates LawnSite Member
    from North
    Messages: 45

    :confused: Why such a difference? The Gravely is a 60" with a 25hp and the Ferris is a 61" with a 25hp.
  2. jtkplc

    jtkplc LawnSite Silver Member
    Messages: 2,656

    2 things...

    The equation for finding acres per hour is "Ground Speed X Deck Width / 99 for 100% efficiency (which is impossible) or /120 for 80% efficiency."

    The Gravely goes 13 mph and the Ferris you mentioned only has a top speed of 10 mph. Ferris used 80% efficiency in their equation, while Gravely used 100% efficiency in theirs.

    13 mph X 60" deck / 99 = 7.8787...

    10 mph x 61" deck / 120 = 5.0833...

    Make sense?

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