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Lawn Mower Blade Questions

Discussion in 'Lawn Mowing' started by pclawncare, Jan 31, 2007.

  1. pclawncare

    pclawncare LawnSite Senior Member
    Messages: 991

    I am just curious and have never asked, but what is the reason for high lift, med lift, and low lift blades. I understand that the high lift generates the most lift for the gass towards the deck, will these high lift also be the best as far as moving the grass towards that exit of the deck. The mower inquestion is a grasshopper with a 60" deck. I run gator blades now, but at almost twice as much i am looking to change to the straight blade set. Since i dont mulch with this machine just blow i dont see the advantage of the gator blades. The only reason why i was running them is because when i first bought the machine i intended to mulch with it, but was not happy with the mulching performance. Anyway i mow in fairly sandy condions and i was wondering if the low lift blades would reduce wear on the underside of the deck.
  2. Mike M

    Mike M LawnSite Bronze Member
    from usa
    Messages: 1,988

    I found that my mower (exmark 48 15hp) with low lift blades mulches better than the gators. I have less blow out and cleaner cuts, less grass stuck under the deck, etc. When you lower the lift, you increase the power. That makes a big difference for my particular mower.

    Lots of stuff on here if you search blades, also, look in the exmark forum for blade info., they do a nice job describing benefits/conditions for blade types.

    You may like your mulch-cut better without those gators.

  3. pclawncare

    pclawncare LawnSite Senior Member
    Messages: 991

    Thanks mike for the input i think since my particular machine has a 23 hp so its not a huge motor, but it seems like the gators cause alot of extra drag on the blade reducing blade speed i noticed at least on my john deere walk behind that i have i am thinking about trying any of the lift blades gators are over rated
  4. mowpart rep4

    mowpart rep4 LawnSite Member
    Messages: 27

    i have heard that the high lift blades were better in wet conditions lower lift were better in dry condition

    WWW.MOWPART.COM try us out for your blade needs also check out our
    green book for help on trading ztr mowers
  5. pclawncare

    pclawncare LawnSite Senior Member
    Messages: 991

    question to the mowpart rep i assume that they charge shipping on the blades correct? Is it a flat fee or is it by the blade?
  6. txgrassguy

    txgrassguy LawnSite Gold Member
    Messages: 3,083

    To understand mulching performance and the impact different blade designs have on mulching, you first have to realize about airflow.
    With a contained baffle system common to most mulching designs, a high lift blades creates a very turbulent airflow condition with-in the contained area.
    Think of this as if you placed an empty 5 gallon bucket on the ground then introduced a high volume of air underneath the bucket.
    It is inevitable that the large volume of air is directed downwards and this re-directed airflow disturbs the laminar flow characteristics that a rotating blade produces behind the foil or raised wing area on the rotating blade.
    The turbulent flow creates an exponential drag problem as the higher the rpm, exponentially, the turbulent flow creates additional drag hence the increased fuel use and wear on the machine not to mention that the grass blades are not being cut uniformly as the blades of grass are bing displaced due to the volume of the turbulent flow.
    This is principally why low lift or the stepped design is necessary on a mulching type blade to minimize the impact of the turbulent flow on both the blade, the grass and in the contained area of the baffle.
    To understand different blade designs in an open discharge deck, here the grass type and predominant soil condition will dictate blade use.
    The resiliency and turgor of the different species of turfgrass mandate a different blade design to achieve a uniform cut.
    Generally, a good rule of thumb is that the cool season, or C3 turfgrass, has a markedly more thin leaf tissue construction meaning the resiliency and turgor have different characteristics than warm season, or C4 turfgrasses.
    At the higher height of cut common to C3 turfgrasses, a greater volume of air is needed equating to higher lift in order to obtain adequate airflow across the trailing edge of the blade to minimize turbulent flow.
    C4 turfgrasses are generally mown at lower heights, the resiliency and turgor of the turf is different meaning less airflow is needed to achieve an adequate cut. However, the aerial density of the C4 turfgrass mown typically mean more material is being cut from the turfgrass, equating to an increase in the effect of the necessary laminar flow by the interference of the clippings themselves. To minimize this effect, one has to experiment to find the best height of the foil on the blade to adequately cut the leaf tissue of the grass blade with out introducing increased turbulent flow which would create discharge problems, increased fuel problems and shorten the life of the machine and blade.
    Now, if all of this isn't enough, different soil conditions, turf types and environmental factors all combine to through a wrench into blade design and adequate mowing performance.
    Unfortunately, due to the myriad of variables in mowing conditions, etc - there doesn't exist a "perfect" blade which will work in all conditions.
    So you need to experiment based on the conditions common to your area.
  7. mowpart rep4

    mowpart rep4 LawnSite Member
    Messages: 27

    thanks for asking the shipments are charged by the weight
  8. lawnprosteveo

    lawnprosteveo LawnSite Bronze Member
    from Tulsa
    Messages: 1,930

    I run mulching kits on my mowers. I think the mulching type blade does the best. Especially on leaves. It seems the hi-lifts did better when I was side discharging....I'm only basing this on my mowers and yards...dont know how it would do for others..
  9. 1grnlwn

    1grnlwn LawnSite Bronze Member
    Messages: 1,261

    To answer your question. Yes high lift blades move the material out the shute faster and farther. And yes flatter blades are more economical in sandy soils. Laminarly speaking!:dizzy:
  10. LandscaperPro

    LandscaperPro Sponsor
    Messages: 461

    LandscaperPro has a HUGE assortment of Blades for nearly EVERY Commercial size unit out there.


    Flat Shipping fee, not by weight.

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    ***use the Coupon Code "LAWNSITE" when checking out to recieve an EXTRA 5% OFF, just for being a Lawnsite member!

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