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

[4570Man]

I’m betting this generator head powered with a 40 hp diesel will stomp all over the efficiency of a regular person grade pto generator. This head is a quality piece that is probably more efficient than the much smaller and cheaper head. There’s no parasitic loss to a gear box if it’s direct drive. There’s no parasitic loss to the tractor either. And retaining the use of the tractor counts as useful.

 

[ptsg]

And if the DPF light comes on, you can simply provide power to the neighborhood for a while just to load the tractor enough for a proper DPF cleaning action.

 

[radios1]

I am curious, though. it was never mentioned, but the second picture shows the proper diesels to mount the heads on, THAT would have been best.. and as far as efficiency goes, neither a gasoline nor a diesel gets more than a few percent efficiency!. but there are aircraft APU's that get 40% to 70% efficiency, the only problem is you'd need to remove the generators from them, since they are 400 cycle units, and mount your gen head to it, the other problem is, you'd have to make an interesting muffler, since the APU's are small Jet Engines..

 

[TheFarmerInAdell]

Speaking of diesels, you could look into a old box van with a 4BT Cummins in it. Or an old school bus with the 6BT (same as the Dodge cummins). Then you could turn 1800 RPM direct drive. And you would have a nice place to store it and keep it covered!

BTW, why did you say "Jeep" when it's only 2wd? At least you admitted that it wasn't a real Jeep. :laughing:

 

[KubotainNH]

It's not a "real" Jeep as it's only 2WD unfortunately. I'm not sure how the Jeep will react to having the weight of a small car sitting in the back seat, but I imagine it will at least squat a bit. The rated payload is 1488lbs, so I would be exceeding that by 300lbs if I just crammed in. But I would be removing seats, carpets, misc creature comforts which might bring it down to within its payload range.

2WD Jeep is blasphemy! That said, I've had 3 XJ's and none like too much weight in the back but that is easily fixed with some steel seeing this isn't a road beast anymore. The leaf springs on these are made for comfort not extra weight. The 4.0 has plenty of low RPM torque to run this setup, it would be great if you could gear it to run so the motor is at 1800 RPM or half the speed the gen head needs.

 

[BigBlue1]

2WD Jeep is blasphemy! That said, I've had 3 XJ's and none like too much weight in the back but that is easily fixed with some steel seeing this isn't a road beast anymore. The leaf springs on these are made for comfort not extra weight. The 4.0 has plenty of low RPM torque to run this setup, it would be great if you could gear it to run so the motor is at 1800 RPM or half the speed the gen head needs.

Doesn't sound like it is really THAT much extra weight that would be going back there anyway. I mean if a Ranger can carry this boulder then a Jeep can carry a generator...

 

[strantor]

I知 betting this generator head powered with a 40 hp diesel will stomp all over the efficiency of a regular person grade pto generator. This head is a quality piece that is probably more efficient than the much smaller and cheaper head. There痴 no parasitic loss to a gear box if it痴 direct drive. There痴 no parasitic loss to the tractor either. And retaining the use of the tractor counts as useful.

I cannot find published efficiency numbers for this head. Heads this "small" are apparently sold exclusively coupled to Cat engines, and the only efficiency-related data Cat publishes is the overall efficiency of the genset (engine + head), and fuel consumption data for various load from 25% load to 100% load. Caterpillar publishes much more detailed specs on their larger units, and they are typically 89% - 94% efficient at 25% load, and 95% - 97% efficient at 100% load.

The head is going to be less efficient at lower loads, as parasitic loss constants will occupy a bigger piece of the pie. I'm thinking that at any given percent of load, there will be the (more or less) fixed combined loss of generating the rotating field current, plus the load of spinning the fan, plus bearing losses, air drag of the spinning rotor, etc. I will be operating the head exclusively below 15% its rated load, usually 10% or less. So in order to estimate efficiency below 25% I've just taken the numbers from the larger generators and calculated the waste kW @25% load as a fixed parasitic loss, which looks like this:
...90% efficiency at 25% load, that's:
210kw * 0.25 = 52.5kw generated @ 25% load.
(1/0.9) * 58.33 kW mechanical
58.33kW - 52.5kW = 5.8kW (7.7HP) waste

So that's 7.7HP (conservative/worst case) just to spin the thing, with no electrical load.

If I were to utilize this thing at 10.5kW (5% rated load), powering my house, and there was 5.8kW tacked on top, that's only 64% efficiency. BUT...

I've done the math already on the field current generator and that's 1HP/746W.
Maybe another 1HP for the bearings, rotor drag, etc.
So I think it's reasonable to assume the big fan accounts for about 5HP. It's a pretty big fan.
That fan is designed to move the waste heat of a 210kW load. At 95% efficiency, that's 11kW of waste heat the fan is responsible for getting rid of. I won't be dissipating anywhere near that. I'll have the heat generated by field coil (746W) plus whatever inefficiency of generating 25kW max, so maybe 2kW.
I think I can ditch the fan, or at least shave the blades so that they don't throw nearly as much air.
I think I can this beast within the 95%-97% efficiency realm at my max load, with a single easy modification.

 

[strantor]

BTW, why did you say "Jeep" when it's only 2wd? At least you admitted that it wasn't a real Jeep. :laughing:

2WD Jeep is blasphemy! .

You think I would turn a REAL jeep into a home appliance? Come on!

 

[4570Man]

I cannot find published efficiency numbers for this head. Heads this "small" are apparently sold exclusively coupled to Cat engines, and the only efficiency-related data Cat publishes is the overall efficiency of the genset (engine + head), and fuel consumption data for various load from 25% load to 100% load. Caterpillar publishes much more detailed specs on their larger units, and they are typically 89% - 94% efficient at 25% load, and 95% - 97% efficient at 100% load.

The head is going to be less efficient at lower loads, as parasitic loss constants will occupy a bigger piece of the pie. I'm thinking that at any given percent of load, there will be the (more or less) fixed combined loss of generating the rotating field current, plus the load of spinning the fan, plus bearing losses, air drag of the spinning rotor, etc. I will be operating the head exclusively below 15% its rated load, usually 10% or less. So in order to estimate efficiency below 25% I've just taken the numbers from the larger generators and calculated the waste kW @25% load as a fixed parasitic loss, which looks like this:
...90% efficiency at 25% load, that's:
210kw * 0.25 = 52.5kw generated @ 25% load.
(1/0.9) * 58.33 kW mechanical
58.33kW - 52.5kW = 5.8kW (7.7HP) waste

So that's 7.7HP (conservative/worst case) just to spin the thing, with no electrical load.

If I were to utilize this thing at 10.5kW (5% rated load), powering my house, and there was 5.8kW tacked on top, that's only 64% efficiency. BUT...

I've done the math already on the field current generator and that's 1HP/746W.
Maybe another 1HP for the bearings, rotor drag, etc.
So I think it's reasonable to assume the big fan accounts for about 5HP. It's a pretty big fan.
That fan is designed to move the waste heat of a 210kW load. At 95% efficiency, that's 11kW of waste heat the fan is responsible for getting rid of. I won't be dissipating anywhere near that. I'll have the heat generated by field coil (746W) plus whatever inefficiency of generating 25kW max, so maybe 2kW.
I think I can ditch the fan, or at least shave the blades so that they don't throw nearly as much air.
I think I can this beast within the 95%-97% efficiency realm at my max load, with a single easy modification.

Maybe for the head itself. You’re taking a 2000 or more engine and gearing it down to 540 RPM and then putting it through another gear box to get it back to 1800 rpm plus any other loses that happens instead the tractor. Assuming the engine works at the same efficiency and the head works at the same efficiency a direct drive unit will be more efficient. Robs statement is blatantly wrong in an apple to apple comparison.

 

[strantor]

I got some bearings in the mail yesterday and I know I said I wasn't going to work on this for a while but seeing the bearings just sitting there is making me itchy. So I decided to get started machining the shaft adapter and bearing housing. For that I'm using this chunk of rusty steel which is a remnant of a project abandoned long ago. I was going to try to build a DIY lathe years ago, and this is what was supposed to be the spindle and chuck. It's a piece of 2" shaft that I turned down at the end and threaded 1.5"NPT and threaded this piece of 7.5" solid round stock onto it. I made it after hours on a lathe they had at a place I used to work (with permission, off the clock).

It's a good thing it has that shaft sticking out, because otherwise I wouldn't have had a way to chuck it up in my tiny lathe. It is requiring some creativity to machine it. I have arranged my tool holder in the most awkward and unorthodox way ever, and can just barely turn the OD.

 

[Sawyer Rob]

Maybe for the head itself. You羆*e taking a 2000 or more engine and gearing it down to 540 RPM and then putting it through another gear box to get it back to 1800 rpm plus any other loses that happens instead the tractor. Assuming the engine works at the same efficiency and the head works at the same efficiency a direct drive unit will be more efficient. Robs statement is blatantly wrong in an apple to apple comparison.

More lack of reading and comprehension going on here...

The OP SAID he wanted to take that mega head gen head and gear it to 540 to be run off his small Kubota... He said, he was going to use a car rear end to do it... Yes, that all was in his original posting.... and that is what "I" answered.

I also said it was going to be a big load for that small tractor and use more fuel than if he had a "properly sized" gen head...and it will... Now, that isn't blatantly wrong!

Now, have you considered a course in Hooked On Phonics?? lol

SR

 

[4570Man]

There was also mention of direct driving the head.

 

[strantor]

Well today was eventful. What should have taken until lunch took until dinner, and resulted in bloodshed and bruises. Machining that big chunk is more than my little lathe was built for. I had to cut the stub end off the rotor so the flange adapter I'm fabricating can mate up. It would have taken 5min if the bandsaw fit, but the space was too cramped. So I went after it with a cordless sawzall, which worked, but was taking forever. 4 batteries drained, 3 blades ruined, I gave up on the sawzall and put an old 14" chopsaw blade (worn to ~9") on the angle grinder and cut it off with that. At the end the blade pinched and pulled my hand up against something that took a big chunk out of my hand.

After a successful fit test I put the adapter back in the lathe the other way and tried to remove the old rusty tapped stub with the parting tool, which snagged and popped the whole 40+ lb adapter blank out of the chuck and slammed it down on the back of my other hand. I called it a day after that. Had a chili's burger for dinner, it was excellent.

 

[Industrial Toys]

Hope you budgeted for a pack of bandaids.

 

[texasranger556]

I've done some sketchy stuff, but I don't think I'd attempt that cut off wheel setup. Glad to hear you didn't fare worse!

 

[KWentling]

Just a clarification on the captured bearing. The bearing itself is just a common ball bearing, not a thrust bearing of any kind. If it's captured the housing the bearing fits in has only enough width for the bearing and is captured by the bearing cap allowing no axial movement. The end opposite the engine in the original use was likely a floating setup. It too is probably just a common ball bearing, but might also have been a straight roller bearing with a separate straight inner race. In the ball bearing case, the float would be in the housing being wider that the bearing and allowed to move axially as needed. That housing would not necessarily have a bearing cap.

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.[/QUOTE]

 

[strantor]

Just a clarification on the captured bearing. The bearing itself is just a common ball bearing, not a thrust bearing of any kind. If it's captured the housing the bearing fits in has only enough width for the bearing and is captured by the bearing cap allowing no axial movement. The end opposite the engine in the original use was likely a floating setup. It too is probably just a common ball bearing, but might also have been a straight roller bearing with a separate straight inner race. In the ball bearing case, the float would be in the housing being wider that the bearing and allowed to move axially as needed. That housing would not necessarily have a bearing cap.

Does this look right? I spent most of the day planning it out and machining it. Cut two disks out of scrap 3/4" plate with an acetylene torch. The plate on the outside is machined with a outer recess to nest into the bellhousing opening, and an inner cutout to for the bearing to nest into it. The other plate goes inside the bellhousing and isn't machined (yet, might just leave it that way) except for having 4 tapped holes. It's only purpose is to give the bearing and outer flange something to bolt to. The fit is pretty good; not a press fit, but close. Maybe 2 or 3 thou of play total (before tightening the bolts)

 

[KWentling]

Does this look right? I spent most of the day planning it out and machining it. Cut two disks out of scrap 3/4" plate with an acetylene torch. The plate on the outside is machined with a outer recess to nest into the bellhousing opening, and an inner cutout to for the bearing to nest into it. The other plate goes inside the bellhousing and isn't machined (yet, might just leave it that way) except for having 4 tapped holes. It's only purpose is to give the bearing and outer flange something to bolt to. The fit is pretty good; not a press fit, but close. Maybe 2 or 3 thou of play total (before tightening the bolts)

Looks like that should work.

 

[strantor]

After a month of dormancy I decided to make some time to work on this. The shaft adapter that I made previously was a good fit for the shaft, I guess because things were hot from machining and now that they're cool, dimensions have changed. My shaft is now a sloppy fit for the hole. I don't have a way to precisely (down to thousands of an inch) hold two pieces of metal concentric for welding. So I opted to knurl the end of the shaft and then force it into the adapter with a hydraulic press. It worked, but not very well. There is about .003" of runout right where the bearing will ride, which is probably borderline OK, however out at the end of the shaft where I plan to put a coupler, there's about .015" of runout. I will need to be creative with my coupling solution or else it might rattle itself to death.

I went ahead and did a fit test after welding and it looks like I'm going to have to machine that haggard acetylene-cut plate inside the bellhousing because it collides with the shaft adapter right before the bellhousing gets snugged up.















P.S. The pictures show the shaft adapter held on with a janky bolt/washer setup. That's NOT how it's going to be. That was just a quick fix to make it stay put for the fit test.

 

[LouNY]

Have you considered chain couplers for a coupling, they will accept some runout.
Chain Couplers | Shaft Couplers | Power Transmission | www.surpluscenter.com