60 MMM Streaking

[theboman]

I put new blades on my 60" MMM (B7500HST) and did them one at a time (one off, one back on). I could tell how the old blade was on the deck and put the new on exactly like the old one. I haven't had any problems. My grass looks great after cutting.

Now that I think about it seems like I checked my blades and they were exactly the same and there is now overlap of the blades on the deck. I got thinking how a mower can cut a 60" path evenly when the blades are space that way...then I realized I bought my tractor to mow the grass and I pay folks for things to work right and let them figure out the engineering.

It sounds as if one of the blades is on upside down, or you have set of mismatched blades.


</font><font color="blue" class="small">( Check your manual on that one. I just replaced the blades on my B7500's 60" deck and the blades are supposed to be in a certain alignment. The manual also says that periodically they should be repositioned back to that orientation. Now, why there would be a specific orientation on a belt drive system is beyond me and I doubt that no matter how they are positioned would have anything to do with striping. When I read this, the first thing that occurred to me was that it was more for balance than anything else......but I may be wrong.

That said, I also inadvertantly installed one of my blades upside down and it does a lousy job of mowing when you do something dumb like that! Fortunately, it was the one by the chute and I managed to switch it without having to remove the deck.

Jeff )</font>

 

[Egon]

On the three blade mowers the middle blade is set forward of the outside blades allowing for an overlap on the cut without hiting blades. Three blades on a straight line would require a positive positioning system a belt does not have.

Egon

 

[Jeff396]

<font color="blue"> I got thinking how a mower can cut a 60" path evenly when the blades are space that way </font>

I guess that's why they put the center blade further forward. That way the outside blades can be squeezed in just enough behind the center one to cut everything. Otherwise, they would have to use a gearbox to keep the blades ralationships constant to prevent them from hitting eachother.

Egon beat me to it...

Jeff

 

[theboman]

It's like a Thermous bottle sort of, a Thermous keeps hot things and hot and cold things cold and it don't have no temperature controls or nothing.

 

[Jeff396]

That's why I buy one Thermos for hot and one for cold and label them so I don't mix them up. Switching back and forth too often wears out the automatic hot cold mechanism doohicky. /forums/images/graemlins/smile.gif

Jeff

 

[sandyc]

You might want to make sure you are using enough RPM's to get a good cut.

 

[surfran]

Tom,

Here is a photo from under my new 60" MMM. You can see the tab facing up toward the deck.

Hope this helps for a quick look before removing. If they look like there installed ok, I would check the cutting edge carefully to make sure it is sharp.

 

[NY_Yankees_Fan]

Thanks for the picture it helps a lot. Will check it out and let you know. I am thinking they are installed correct, I have to check the size, it that is OK then the only thing it can be is the way they are positioned. Why is nothing ever easy!
/forums/images/graemlins/mad.gif

 

[Anonymous Poster]

Sounds like you might have a set of blades (or a mix) for a 54" mmm on your 60.
DaveL

 

[surfran]

If it's any help, they should be about 20 5/16" for the 60MMM. I had measured all three of mine last weekend and they are all the same length.