OT, Finish mower

[Terry Joe]

I was thinking of speeding my finish mower up about 10-20% by installing a smaller pulley on the bottom of the mowers gear box. Any ideas of how much smaller the pulley should be for a slight speed increase? The mower is a quality built machine and I am sure it could withstand a small speed increase. I like to mow in 3rd gear and the grass has a few blades of grass that didn't get cut clean.

 

[souNdguy]

i won't speak to the (lack of?) safety with over speeding the mower.. however as to the pulley, a lil bit of math will show you what the % increase in diameter does to the circumference of the pulley.

remember C = Pi * D

plug in different diameters to see what that does to the circumference, then compair % change

you might have to estimate pto speed, and it will help if you know blade tip speed.. etc..

soundguy

 

[Roger in Iowa]

To speed it up, I believe you will need a larger sheave on the bottom of the gearcase! Not smaller.

 

[Terry Joe]

Your right, don't know what I was thinking. I'm thinking of going 1 inch larger.

 

[gahorN]

The centrifugal forces on those blades will increase exponentially...not a safe thing to do at all...and not likely to improve your "cut" in 3rd gear anyway.

 

[Tom N MS]

I agree. Third gear is just for the road anyway..much too fast unless your lawn is as smooth as a football field..Nowhere I"ve ever had the privilege of cutting has ever been that smooth.

 

[Terry Joe]

3rd gear is not a road gear, not in my tractor anyway, and my yard is very smooth. Been mowing in 3rd gear for 10 years now with good results. When I built our house, I used my 8N and plowed, disced, and dragged the dirt in all directions until it was as smooth as a babys butt before I sewed the grass. I did all 5 acres this way.

 

[Paul in MN]

Does your tractor have a Sherman O.D. tranny? If so, you could set it in 2nd gear main shift with the OD of the Sherman engaged. This will give you about the same ground speed as 3rd gear, but the PTO is speeded up beyond the normal near full throttle 540 RPM. But there is one drawback, the hydraulic pump is also speeded up by the same ratio, and if it is worn, it may be destroyed. Now, if you throttle down in this 2nd OD, you still have good ground speed and probably are running the PTO at just a bit over the 540 which should be OK for everything.

Just a thought.

Paul in MN

 

[Tom N MS]

Sorry--forgot we were talking 8N