ST 15 on PTO with Belt Drive

[injin man]

The Head is a Brushed ST15.

I'm buying a friends project, he's rewired the head. It's got a cogged belt pulley
and PTO Shaft. To use the PTO I'll need the Speed increaser gearbox or a rig like
this one: http://www.youtube.com/watch?v=3w9aeHNAHGk&feature=related

What do you guys think it the best solution Belts vs Gear Box, the Pulleys might
cost as much as the $230 GB from Central Georgia.

[Henry W]

I like what the person has on You Tube.

Running an ST-15 at 1800 rpm I would run at least a two groove B type V belt set up.

Pulley sizes of:

Powered Driver Pulley Diameter 18.40"
https://www.surpluscenter.com/item.asp?item=1-2BKH190&catname=powerTrans

Driven Object Pulley Diameter 5.60"
https://www.surpluscenter.com/item.asp?item=1-2BKH62&catname=powerTrans

The pto shaft rpm will have to run at 528.324 rpm to run the generator head at 1800 rpm. That is very close to the recommended 540 rpm of most Tractor pto's. All you would have to do is throttle down the engine just a bit

Henry

[Crofter]

I rigged up a similar PTO drive running a flat multi rib belt off the outside of a mounted car tire and wheel as the large pulley. The difference in diameters gives a poor amount of wrap around on the gen pulley and requires an idler pulley to induce more wrap or slippage is a problem. I would go with the gear box reducer from Tom . More compact and much easier to safety guard!

[Henry W]

Here is the gearbax Tom sells.

http://cgi.ebay.com/GENERATOR-PTO-DRIVE-GEAR-BOX-540-RPM-1800-Rpm-/160508750261?pt=BI_Generators&hash=item255f1129b5

You will need to buy a coupling also to hook it to the Generator head.

[Henry W]

If you decide to run a belt setup than I agree with Crofter,
Running a V belt setup like the person posted should have an idler setup on the slack side. That is easy enough to do while laying it out.

Henry

[Henry W]

If you want a to run a belt setup I had time to think about it and what might be a good simple setup is to run a four pulley setup. Also this setup should not need an idler assembly.

Purchase the following pulleys from Surplus Center:

Qty-2   6.1" two groove B type V-belt pulleys.
https://www.surpluscenter.com/item.asp?item=1-2BKH67&catname=powerTrans

Qty-2  11.4" two groove B type V-belt pulleys.
https://www.surpluscenter.com/item.asp?item=1-2BKH120&catname=powerTrans

This would require a two shaft setup:

The shaft for the PTO setup requires one 11.4" pulley.
 The second shaft requires one 6.1" pulley that will be driven from the PTO shaft 11.4" pulley. And on the other end of the second shaft I would run the other other 11.4" pulley.
 The last pulley which is 6.1" goes to the generator head.

In the lawn care industry all the high powered Z-turn mowers up to 30hp use only one B type Kevlar V-belt on their drive unit to run the mower deck.

For $132.00 you will have a pulley setup that will hold up very well.

The advantage to this setup compaired to the two pulley single shaft setup is this setup will give a much better belt wrap which will help handle a much greater load and increase belt life.

Running the pto shaft at 540 rpm will run the generator head at 1884.288 rpm. With this setup the engine speed of the tractor has to be reduced slightly to bring the speed down to 1800 rpm.


Henry

[injin man]

I'll start looking at options from here, the Belts seem to me
to be smoother than the gearbox although not as compact.

[vdubnut62]

Belts seem to me to be smoother than the gearbox although not as compact.

And a hell of a lot cheaper to repair!
Ron

[injin man]

Belts seem to me to be smoother than the gearbox although not as compact.

And a hell of a lot cheaper to repair!
Ron

I'm with you, off the shelf (if there ends up being one) is the way
to go. Definitely cheaper to keep a set of spare belts than a spare
gearbox.

[Henry W]

This information should help you a bit if you decide to build a 4 pulley set up.

You have everything here to start laying out the PTO Genset.

11" Center to Center Distance on pulleys will give you about 3" clearance between the pulleys so the belts can be changed by sliding pillow blocks and/or generator head. The clearance from the widest part on either side of the  ST-15 Generator Head to the side of the second shaft (which I figured 1-1/2 dia. for the shaft) will give roughly 2-1/4" of clearance  (+/- 1/2").

With the info provided on which pulleys to buy at Surplus Center, a B or BX type belt 50" long will work perfect for this project.

P.S. I also posted some PDF files below from a Pulley and Belt Calculator.

Henry