Seat time

[ethiojazz]

Re: Seat time / B7500 MMM streaks

The Blades have to line up ???? No wonder I was not getting the cut that I expected. I had assumed that the blades should not be lined up so that they create a constant air movement, but I guess that makes sense.

Will try changing the alignment this weekend.

Thanks for the heads up. /forums/images/graemlins/smile.gif

 

[DougM]

Re: Seat time / B7500 MMM streaks

The Blades have to line up ????
As far as I know the blades will move out of alinement each
time u mow...
they are set on the belt not gears....

Doug

 

[Anonymous Poster]

Re: Seat time / B7500 MMM streaks

Not sure myself. Are you aligning the blades by sliding against the belt until they are lined up from side to side(blade tip to blade tip /forums/images/graemlins/confused.gif)???
It makes no difference if they are lined up like that or not. They will never stay in alignment anyway.
DaveL

 

[theboman]

Re: Seat time / B7500 MMM streaks

I'm no engineer, but they do stay in alignment. They may give a bit, and if you mow stumps and rocks they'll be pretty darn close to the way you put them on. I mowed for 4+ hours now and the streak I was getting is completely gone.
And I bet (if gambling was legal) the blades are exactly the way I aligned them.
Get the middle blade and align it with the left one and tighen them down, and then align the right one with the middle blade and tighten it down.
It's all about airflow and the blades lift the grass to cut, When the blades were not aligned there was not enough lift on the side where only blade was out of alignment.
I'm sure they were aligned when I first removed the blades, and remember spinning that one pulley without moving the other two, so when I originally put on the blades I had them exactly as the original blades but that one pulley had been turned without moving the others.
Now the outside blades will align with the middle blade and it cuts just as it did when it was new.

 

[ethiojazz]

Re: Seat time / B7500 MMM streaks

I agree with you. The belt is supposedly rotating all the blades at the same speed and therefore the number of revolutions that each blade goes through as well as the speed of each blade should be exactly the same. Unless one blade was slowed or stopped, they should remain in alignment.

It has been too wet to try that change but I will let u know if it is different when I go out to mow.

 

[heith]

Re: Seat time / B7500 MMM streaks

couldn't they individually slip.

 

[DK35vince]

Re: Seat time / B7500 MMM streaks

</font><font color="blue" class="small">( couldn't they individually slip. )</font>

Yes

 

[Anonymous Poster]

Re: Seat time / B7500 MMM streaks

Thats what I was trying to say (sorry if I was a little short with you folks). Unless the belts and pulleys are cogged to assure alignment (like a timing belt on an overhead cam engine) or the driveline is geared, each time you start the mmm the blades will slip a little bit as they try to come up to speed due to inertia. Also, even a miniscule difference in pulley diameter will equate to a very large relationship change between blades at the speed they are turning. They will never stay in postion relative to each other using a v belt drive, and were never designed to do so. Yes, if inertia and tolerances were not an issue, you would be right. But that is not the case here, unless the b7500 mmm has cogged belts or a gear drive (in which case I'm all wet).
DaveL