Picked up half a megawatt worth of Caterpillar power, think I'll make a PTO generator

[strantor]

I spent 20+ years as a machinist in an electric motor repair shop. We made housings and mandrels to balance and test run alternators and generators so what you are trying to do is certainly doable.

To adapt the pto clutch you could machine a "spacer" to sandwich between the stator housing and the clutch housing, with a 20.128 bore and the appropriate bolt pattern.

Generators and alternators always have one insulated bearing to break the "circuit" through the rotor to prevent arcing through the bearing. Your's likely already has one. The end you build may need to be a "captured" bearing set up to control the location of the rotor. You'll need to see how the existing bearing is set up. One end needs to float.

A timing belt is another option for speed increasing, but they are expensive. I do think you need some kind of clutch set up to give it a soft start and stop feature.

It sounds like you have the voltage/ windings conversion under control. We did that conversion to a 480v 3-phase 40KVA for a home back up system. Had a 4BT Cummins.

It will be interesting to see how this works out.

Thank you for the validation and for the tips. I decided to go ahead and get the Detroit Diesel SAE #1 engine-side (flywheel) bellhousing over the PTO bellhousing because I don't currently have the capability to machine a spacer that large. The engine-side bellhousing already has the appropriate gender and bolt pattern. The 6" hole in the bellhousing is small enough to be in my realm of my 9"lathe's machining ability and I think I can machine a bearing housing to fit that hole.

The guy pulled a fast one on me though. His listing included multiple bellhousings for Detroit Diesel engines and it simply said "$200." When I showed up he told me it would be $300. I had his listing already pulled up on my phone so I opened it up and showed him where he clearly listed it for $200 and he said "that's the starting price. For the bellhousings that go on smaller engines." He seemed unwilling to negotiate but when I started to leave he loosened up. He "made me a deal" for $260. I paid it and took the bellhousing but not without a bad taste in my mouth. $260 is still half the price I can find for a PTO bellhousing of these dimensions.

I was going to go ahead and order a bearing for the end so that it's already here when I get ready to move on this project again, but then I remembered what you said about the captured bearing. I need to check out the existing bearing and see if it has any thrust support built in. If not then I might need to go with a pair of opposing tapered roller bearings on either side of a flange to keep the rotor from walking around in there.

 

[Industrial Toys]

Looks like you might need a pump too!

I messed around with a Deutz off a Compressor, trying to put a Rockford clutch on there. I too had to get the SAE adapter, and that's just another project not finished.

 

[strantor]

The end you build may need to be a "captured" bearing set up to control the location of the rotor. You'll need to see how the existing bearing is set up. One end needs to float.

I was going to go ahead and order a bearing for the end so that it's already here when I get ready to move on this project again, but then I remembered what you said about the captured bearing. I need to check out the existing bearing and see if it has any thrust support built in. If not then I might need to go with a pair of opposing tapered roller bearings on either side of a flange to keep the rotor from walking around in there.

Spent a couple of hours last night in bed not sleeping, thinking about how I would build a double tapered roller bearing setup in such a way that it could be easily assembled, and I think it's more complicated than it needs to be. I think that this simple insert bearing with set screw locking collar would do the trick. what do you think?

One reservation I have about that style of bearing (211-32 bearing), is that I cannot find a speed rating for any version of it from any manufacturer. Some bearings are rated for <1800 RPM, especially the larger ones.

Looks like you might need a pump too!

I messed around with a Deutz off a Compressor, trying to put a Rockford clutch on there. I too had to get the SAE adapter, and that's just another project not finished.

Not sure what you mean by pump. But the flywheelbellhousing does have a hole to mount a starter, and I'm thinking that might be my solution for getting the genny up to speed before engaging the PTO. Mount a Detroit Diesel engine flywheel inside the bellhousing it was born be in, with the starter to match.

 

[texasranger556]

I think he meant it looks like you've gotten a lot of rain recently judging by the puddles

 

[strantor]

I think he meant it looks like you've gotten a lot of rain recently judging by the puddles

Oh, HAHA! The thought didn't even cross my mind. I'm so used to the standing water it doesn't even register anymore. It's been like this for months.

 

[Industrial Toys]

I can find you a 6" pump with a Cat motor!

 

[LouNY]

One other thing to consider you are wondering about getting the head up to speed without tearing up your pto, I would add an over running clutch to your tractor end pto for shutting down. You might not find the starting load to be that much if you leave the excitation off till you are at speed.
Good Luck with your project.

 

[strantor]

One other thing to consider you are wondering about getting the head up to speed without tearing up your pto, I would add an over running clutch to your tractor end pto for shutting down. You might not find the starting load to be that much if you leave the excitation off till you are at speed.
Good Luck with your project.

Never heard of that, looked it up. That's absolutely a good idea and I hadn't even considered a need for something like that. I would hate to put in all that work for a solution to get head up to speed without damaging the PTO clutch, only for it to be destroyed by an unexpected shutdown of the tractor. Thank you very much for the suggestion! I will do it!

 

[strantor]

I can find you a 6" pump with a Cat motor!

I was thinking more along the lines of 1,200 (+/- 200) electric 1/4hp submersible pumps buried in a grid across the property, powered by an unreasonably large generator head. :laughing:

 

[texasranger556]

I was curios about this so I ran some numbers to compare how much energy it would take to spin up your proposed generator vs a 6 foot brush cutter. Had to make a lot of assumptions, but here goes:

Calculate the moment of inertia for your estimated 600 lb rotor with a 20" diameter, works out to 208 lb*ft^2. You need to run it at 1800 RPMs, so once rotating at that speed, it would have roughly 3955 Joules of kinetic energy.

Then consider a 6' brush cutter with a 6' steel blade 4" wide and 1/2" thick (I know blades are 3 piece, but for the sake of argument...). That is roughly 41 lbs of mass. The moment of inertia comes out to 125 lb*ft^2. Assuming a nominal blade tip speed of 15,000 ft/min, that is 800 RPM. Kinetic energy of the spinning blade is 468 Joules. That means the rotor would take roughly 8 times the energy to bring up to speed vs the 6' brush cutter.

This does not account for driveline loss, wind resistance, magnetic fields, etc. which could be significant.

If the rotor is actually 18" diameter, that drops the MOI down to 169 lb*ft^2, and the kinetic energy to 3200 J. Still a lot. I attached an excel sheet so you can play with the numbers (highlighted yellow).