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telling the difference bettween Insta-Act power packs

Discussion in 'Fisher Engineering Discussion' started by NHresident, Mar 27, 2010.

  1. NHresident

    NHresident Senior Member
    Messages: 304

    Hi how can I tell the difference between a 2500 PSI Insta-Act for the smaller blades and a 4000 PSI one for the bigger blades.Is it as simple as looking to see which PSI amount is on the unit or some other way THANKS
  2. JFon101231

    JFon101231 Senior Member
    from CT
    Messages: 457


    Anyway to tell if it is off the truck and no stickers are left? Are the 2500psi substandard for a regular 8' HD? I saw on another post a guy had a 9' MC plow and he had that pump, which seems odd that the bigger plow would have the same pump as the smaller blades... Maybe it has to do with volume for the bigger cylinders rather than psi.

    Thanks, Jeff
  3. JFon101231

    JFon101231 Senior Member
    from CT
    Messages: 457

    Is there anyway to tell without a pressure gauge? What would happen if you use a 2500psi unit on a 8' blade, would it just move slower? I picked up one for a good price thinking they were all 4000 psi...
  4. JFon101231

    JFon101231 Senior Member
    from CT
    Messages: 457

    No replies - is the answer there isn't any way to tell without a gauge?
    I would have imagined someone else has had this issue before...
  5. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,415

    Contrary to popular belief, the 2500psi vs. 4000psi refers to the crossover relief setting... Not maximum pump output. Other than that setting, there is no difference in the pumps.

    The maximum pump pressure setting for all Fisher (and Western) straight blades is 1750 psi... with the pump against the pressure relief. The actual operating pressure is much less than that.

    As far as crossover relief settings, the bigger (MC series) blades use the 2500psi setting, and the smaller (HD and RD series) use the 4000psi setting.
  6. JFon101231

    JFon101231 Senior Member
    from CT
    Messages: 457

    For the benefit of others who may search and come upon this thread, the following is from a PM with cubicinches:

    "As I said, the operating pressure is the same on all pumps, so you'll see no difference in how the plow operates, as far as speed or power, etc. Crossover relief only comes into play when striking an object while plowing, and the angle cylinders have to relieve pressure... that's it. "

    Therefore, the normal up/down and left/right functions of the plow will be same regardless of which pump (2500psi on LD & MC, or 4000psi on HD and RD) is used.
  7. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,281

    Thats sad to think a 1200+lb MC blade uses the same hydraulics as a 6xxlb 7'6" blade.
  8. ChrisFromBoston

    ChrisFromBoston Junior Member
    Messages: 11

    Why sad?

    I think it speaks to a versatile design that was well-engineered. Especially for us end users it avoids having to keep a huge inventory of spare parts on hand.
  9. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,281

    Simple, time is money and if you're using a underpowered hydraulic unit to move a Municiple plow that takes nearly 10 seconds to angle from one side to another your wasting time. Its the exact reason why Fisher has seperate hydrualics for their Extreme Vee and XLS, competition was much faster. Its like saying a 4 cylinder used in a Chevy Cobalt would work fine in a 2500HD Chevy - sure it'll be slow as heck but it'll be versatile.
  10. bob00

    bob00 Senior Member
    Messages: 143

    ther is 2 inportant value in hydrolics psi and gpm

    psi pressure per squere inche
    gpm gallon per minute

    speed is base on gpm
    power on psi

    so i don t rember exactly how meny gpm fisher unit give out
    but if i recall right all insta act have the same gpm

    then any blade with bigger cylinder bore is slower then the one with smaller cylinder bore

    more psi wont make your blade faster

    and to know witch one is what i dnot know i think ist just setting in the relif valve both unit seem to have same part in them

    they all use 21501K as pump in the 2500 psi 9825-1 , 9835-1 and the 4000 psi 9840-2

    and cant find part diffrence in all the schemetic
    Last edited: Feb 12, 2012