How much blade speed would I lose?

BustedKnuckles · Dec 8, 2013

Hey guys and gals,

I have a Toro Proline 52 that I just bought with a blown trans. I thought I got a good deal until I discovered the electric pto clutch has been monkeyed with and welded on. The pulley diameter is 7" but I have a good clutch with a 6" pulley. I have the belt tension covered but would it create a noticeable decrease in blade speed? There's probably a formula for this but I'm not a math guru. All help is appreciated.

KennyV · Dec 8, 2013

you will Loose just a little Over 14 percent...
:smile:KennyV

BustedKnuckles · Dec 8, 2013

Easy enough. So I just had to divide the smaller diameter by the larger diameter.

Opinions? Is it worth a shot? A new clutch is more than I paid for the whole mower and I'm trying to justify the project with parts on hand.

BustedKnuckles · Dec 8, 2013

KennyV said:
you will Loose just a little Over 14 percent...
:smile:KennyV

Thanks for the reply by the way.

KennyV · Dec 8, 2013

It will likely work just fine...
Most mowers are intended to have the engines running at 3600 rpm.... but a lot of folks run below W.O.T. so your end results will be like running the factory clutch with the engine running around 3100, it will make some difference on most grasses it won't be that noticeable ... :smile:KennyV

tybilly · Dec 9, 2013

you could always put a wider series belt to add to your blade tip speed.

BustedKnuckles · Dec 9, 2013

It's already got a 5/8" belt so I believe I'm good there. I'm gonna roll with it and worst case, I have to suck it up and buy the $400 clutch in the spring if it needs it.

Thanks for the replies guys.

BustedKnuckles · Dec 11, 2013

Here's my solution.

I started with the tensioner in the old belt guide location (see hole to the right) with a 6" idler pulley. The belt would jump off as soon as the blades were engaged. I ended up at the current location (in a lower part of the deck stamping) with a 4" idler and belt guides off of a Craftsman rider. The arm came off of a Cub Cadet commercial walk behind and I can't remember where I harvested the spring.

I had no idea how a 1" smaller pulley would affect the belt tension and it was quite loose. This mower never had a tensioner but my contraption works quite well.

Save old parts! You never know when they will be needed. This was my most ambitious project to date: A long forgotten Toro Proline 52 walk behind that needed an engine, trans and pto clutch replacement. As soon as the trans arrives it'll be ready to mow!

Carscw · Dec 11, 2013

You will loose blade speed but the pro is it will hold the blade speed better when cutting tall thick grass

BustedKnuckles · Dec 14, 2013

Carscw said:
You will loose blade speed but the pro is it will hold the blade speed better when cutting tall thick grass

That's a good point too.

I'll never find out though, it went to a new owner today and the mower turned out to be rather nice when I finished it.

How much blade speed would I lose?

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BustedKnuckles

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