High speed PTO design reference??

[CalG]

I'm starting in on mounting a Kubota G2546b snow blower on a Kubota B7200 HST.

The tractor has a two speed mid mount pto that outputs over 2100rpm at full engine speed. That's good, because the blower has a 5:1 reduction system feeding the impeller and auger ;-)

Building up the drive line, (**** the Kubota "special" 1 inch-10 spline pto) I'm concerned about driveline whip.

The "stretch" between the underside pto output stub and any bearing supported mid shaft might be up to 3 feet long. Kubota wants a pretty penny for those double ended intermediate shafts, and I have not seen anything longer than 14 inches (p/n 70060-02728)

Will a tubular pto shaft be required? Or will sold shafting between U joints be OK?

The entire mounting is scratch bult around the Kubota quick mount system. So anything is possible. Of course, there is no sense spending $$$ due to ignorance. ;-)

Any suggestions on "High speed pto driveline design"?

TIA

 

[bigdeano]

A 1" solid shaft should easily be good for 3 feet. They used to use solid driveshafts on vehicles. I have a crowbar made from a driveshaft from a 1927 Chevy truck. It measures 1.215 dia x 64" long. It probably turned faster than 2100.

There are undoubtedly engineering formulas you could use, but I don't know them.

 

[Dave M7040]

I'm starting in on mounting a Kubota G2546b snow blower on a Kubota B7200 HST.

The tractor has a two speed mid mount pto that outputs over 2100rpm at full engine speed. That's good, because the blower has a 5:1 reduction system feeding the impeller and auger ;-)

Building up the drive line, (**** the Kubota "special" 1 inch-10 spline pto) I'm concerned about driveline whip.

The "stretch" between the underside pto output stub and any bearing supported mid shaft might be up to 3 feet long. Kubota wants a pretty penny for those double ended intermediate shafts, and I have not seen anything longer than 14 inches (p/n 70060-02728)

Will a tubular pto shaft be required? Or will sold shafting between U joints be OK?

The entire mounting is scratch bult around the Kubota quick mount system. So anything is possible. Of course, there is no sense spending $$$ due to ignorance. ;-)

Any suggestions on "High speed pto driveline design"?

TIA

I am a mechanical engineer. Shafts have critical speeds.

2,000 is not fast. Most rear drive vehicles run the pto shaft at engine speed in top gear so with a gas engine you are talking 5-6,000 rpm. The distance between support bearings is much more than 3 feet.

The tolerances required to have the shaft centered at either end is beyond all but the very best machinists. Keeping the shaft straight when welding on either end is also difficult.

Last indexing of the joints on either end of your shaft is critical.

I am not certain if I understand fully your question. You cannot get the part you need, you don't want to pay for the part you need or, you doubt Kubota's shaft design.

Most Kubota and John Deere front mounted blowers are made by a Canadian company called Rad. They only deal with manufacturers not consumers.

Rad just changes the snow blower color depending upon which company wants a blower.

If you cannot find what you need at Kubota, find a good John Deere parts guy.

If you need a drive line made, seek out truck specialty shops which are shortening or lengthening truck frames constantly and will be able to make you a hassle free quality part.

Dave M7040

 

[zzvyb6]

I bought a JD front snowblower for attachment to my F-935 and along with it came some extra parts, including the front parts and shaft for attachment to a JD-955. The driveshaft is quite long and is hollow but substantial. My background is also mechanical engineering. The key ingredients to your snowblower setup are the phasing of the U-joints between the mid-pto and the front bearing at the radiator area front support bracket. Your snowblower will be raised and lowered through a rather large angular change of the driveshaft between the blower and the front spline stub shaft. This amount of angular change also begs for a CV joint or approximate CV joint here. A true CV joint can be made from a car's drive shaft or you can buy the double joint deal on ebay or from a dealer. You must take into account the length change, too. so the front shaft needs to be extendable. Mine is splined.

I can provide pictures of these shafts if you can't find one. Other than this consideration, you need to make sure your blower is geared for a 2100 rpm input. Mine is geared, some are done with sprockets and a chain. These two methods will also cause concern about what direction your final drive runs at, too. I needed a shaft reverser in the blower driveline because my PTO runs counter to the blower requirements. The shaft reverser + extra driveshaft combo was cheaper that a new gearbox, thanks to a garage sale.

 

[CalG]

I am a mechanical engineer. Shafts have critical speeds.

2,000 is not fast. Most rear drive vehicles run the pto shaft at engine speed in top gear so with a gas engine you are talking 5-6,000 rpm. The distance between support bearings is much more than 3 feet.

The tolerances required to have the shaft centered at either end is beyond all but the very best machinists. Keeping the shaft straight when welding on either end is also difficult.

Last indexing of the joints on either end of your shaft is critical.

I am not certain if I understand fully your question. You cannot get the part you need, you don't want to pay for the part you need or, you doubt Kubota's shaft design.

Most Kubota and John Deere front mounted blowers are made by a Canadian company called Rad. They only deal with manufacturers not consumers.

Rad just changes the snow blower color depending upon which company wants a blower.

If you cannot find what you need at Kubota, find a good John Deere parts guy.

If you need a drive line made, seek out truck specialty shops which are shortening or lengthening truck frames constantly and will be able to make you a hassle free quality part.

Dave M7040

Dave and all, Your replies are appreciated. Thank you all

I should have included a picture of the proposed layout. Front snow blower drives are done in three hitches for these applications.
The intermediate shaft is 1-10 spline to mate with Kubota pto and U-joint standards. This solid shaft is bearing supported on the subframe. More typical U-joint at both ends drive shafts convey power from the pto stub and then again to the blower input.
I agree, 2000 rpm is not fast , but it is four times faster than a typical 540 rpm pto. Where is the cut off between slow and fast? Where is the cut off between long and short? Where is the cut off between solid shaft application and tubular construction (automotive)? Where is the cut off when there is scant room to fit a compatible U-joint to the pto stub? Get my position?

This application is a "custom" fit. So no, I can't just buy the Kubota part. I did order the nearest part that will ease the refit. The bearing supported double spline solid element.
$160 is about the same money as it would cost to purchase the involute cutter to machine the splines (new cutter cost) add the cost of 4130 bar stock and heat treatment, and making one doesn't look like such a good deal. A custom shaft manufacturer quoted over $200 for a shaft splined both ends.

I am surprised that Kubota is the ONLY user of the 1 inch -10 spline for the mid pto. I searched the web extensively Bailey etc. as well. 1-10 spline is not an "off the shelf" configuration. 'Any alternate sources?

That "special spline" also makes it really tough to go to the local driveline shop and ask them to make a hassel free quality part. What are they going to work with?

I'm going to go with the drive shaft that came with the under belly mower. It's much too short for the snow blower frame, so will need to be lengthened. The sliding spline on that piece is "special" as well, it has a skipped spline to assure indexing. A great idea! But it makes replacement parts more difficult. It is only this proposed lengthened drive shaft from the mid pto to the fixed shaft that "might" get long enough to wobble. I sure wouldn't want it going to pieces while under load.