Stub shaft for Yanmar with non-SAE flywheel

[dieselfuelonly]

Hi all, new member here thanks for approving my account recently.  I signed up a month or two ago about it looks like there was a problem with lots of bots so I'm guessing registration was put on hold.  I am purchasing a 10kW ST generator head from a member here to build a small diesel genset mainly for backup power for when a hurricane wipes it out for a week here in NC.  

I have a small Yanmar diesel out of a Thermo King TriPAC APU unit off of a Kenworth I used to own.  Ingersoll brands it as a TK270M, and as far as I can tell it is based off of the Yanmar 2TNV70 with some minor changes such as the flywheel and I believe the output is slightly derated as well as it is designed to simply run an A/C compressor and an alternator without the need to run the trucks' engine to stay comfortable.

The data plate on the engine specifies 7.5kW @ 2400 RPM.  I want to do a shaft coupling from the engine to the generator head which obviously means the output will be further decreased as the engine will only be running at 1800 RPM.

I emailed back and fourth for a while with someone from Hayes manufacturing about stub shafts and flywheel couplings and unfortunately the non-SAE flywheel would require them to make a one-off coupling for me at a cost of $938 which, let's face it, is way too much for this project I'm taking on mainly out of boredom.

Another option I have is I have found a flywheel off a similar Yanmar with a SAE bolt pattern that I could use with a Hayes stub shaft, but by the time I purchase the flywheel and stub shaft I'm sitting at close to $600 just to get things turning.

So right now I'm leaning towards creating my own coupling and was hoping to throw some ideas around.

Here is a picture of the flywheel, along with a crude drawing with the dimensions and bolt circles:






Here is the pulley that Ingersoll attaches to the flywheel to drive the alternator and A/C compressor.  It is 5" in diameter and pilots into the 70mm bore in the center of the flywheel after the flywheel is installed on the crank.  It is bolted to the flywheel using the 6 "B" holes on my drawing.






I am no machinist but know enough to get myself in trouble and can sweet talk the boss into letting me use the old wore-out lathe he bought years ago from a machine shop that closed down.  Here's my idea so far:

If I could find an appropriately sized shaft flange, like the one below, and some appropriately sized keyed shaft from Grainger, McMaster, etc., I could put that in the lathe and machine the back side of the flange slightly to create a lip like the original pulley to pilot it into the flywheel.  Then it's a matter of marking and drilling the bolt circle as I'm sure none of these flanges will end up having a 100mm bolt circle like my flywheel, installing a LoveJoy coupling in between my new DIY stub shaft and the generator and off we go.





I guess I could also purchase a short 1" or so piece of 5" round stock and weld a keyed shaft directly to that, but that is probably a bit out of my skill level when it comes to getting everything perfectly true on the lathe.

Thanks for any input and/or ideas.

[mobile_bob]

if you can machine the oem microgroove pulley to accept a taperlock bushing, then it would be a matter of getting a bushing to fit your shaft, however alignment is critical if you want to connect directly to the generator shaft?  now if you can mount a stub shaft in the taperlock and then couple that to the genhead with a lovejoy or similar rubber coupling then alignment while important is not as critical.  you could be off a few thousands, which is much easier to accomplish.

alternatively you might find a flex coupling to connect the genshaft to the face of the serp pulley you have illustrated, i have seen those made from everything from steel to plastics

multicylinder engine's are much smoother running and much easier on drive couplers, that is a plus.

i can think of another way, something like what i did on my s195 trigenerator setup,
basically you take two steel plates or hubs if you like one of which is sized and keyed to fit the generator shaft, bore them, thread one to accept bolts to bolt them together, and sandwich a rubber disc between the two plates, that is a slip fit into the serp pulley you have, properly aligned, then tighten the two plates together, which squeezes the rubber outwards and makes firm contact with the serp pulley interior bore,  make sure that the steel plate are somewhat smaller in diameter than the bore of the pulley, so that there is maybe a half inch of rubber all around? maybe less would do, having just a bit of flex here is all you are after.  well aligned and it works quite well.

bob g

[dieselfuelonly]

now if you can mount a stub shaft in the taperlock and then couple that to the genhead with a lovejoy or similar rubber coupling then alignment while important is not as critical.  you could be off a few thousands, which is much easier to accomplish.

I like this idea as I could use the pulley to drive a 12v alternator as the engine doesn't have it's own alternator bracket.  Though I would have to take it to a machine shop to have it milled for the taperlock, and that that point maybe it would be easier to just have the machine shop make a stub shaft that I could either pilot into the pulley or the flywheel.  One thing I would need to check would be the runout on the inside bore of the pulley since it was probably not designed with tolerances to have something else pilot inside of it.   Anyone know of a machine shop around NC that could make something like this for a reasonable price? 

[Henry W]

Welcome aboard dieselfuelonly, I think Bob G's idea is a good one. Bob worked couplings hard on the S195 and they held up fine. Looking at the pulley, an SK or SDS bushing might work. It would be easy work on a lathe.

Henry W

[mike90045]

Wow - that was really a back of the envelope drawing  !!

[dieselfuelonly]

So still waiting on a quote from the machine shop about the stub shaft but based on his initial reply I'm guessing it's gonna be out of what I want to spend on this project.  I picked up a stub shaft off of eBay from a Yanmar in a Deere mower that I can probably modify myself to make it work.  The seller told me the flange end of the shaft measures a little over 5", so that that's just a little bit bigger than the belt pulley is.  The back side of the flange end is stepped in so I don't see how I would go about piloting it into the center of the flywheel, so I will need to learn how to very accurately drill the bolt circle for the 4 bolts into the flywheel.  Hopefully I can make it work.  Alternatively, and maybe a better idea, is to drill new bolt holes into the stub shaft rather than the flywheel.  I still see it being a challenge laying this out by hand.



This one isn't the one I bought, but it is what the back side looks like.  I was hoping I could put it in the lathe and machine down the back side to fit the 70mm bore in the flywheel, but I don't think that will be possible.

[glort]

I am after a similar Stub shaft for my Kubota engines.

Anyone know of a source? I'm in Oz but are there any places like tractor joints or types of businesses likely to carry them.... at a reasonable rather than ridiculous price?

[Henry W]

What size engine do you have? Would you know what the engine was spec'd for? APU, Lawn care equipment ... ? Would there be a possibility knowing what manufacturer used the engine on their equipment. There are some large power equipment graveyards that might be able to help.

There could be a remote chance that I might be able to get in touch with the application's engineer in the US that works for Kubota. It's been over 7 year since I spoke to him but there is a possibility. If the engine is complete and original their should be a Spec number along with the serial number on a tag or sticker. It could be stamped on the block somewhere. This spec number should give some info of the OEM manufacturer that bought the engine set up for their application. In times like this it would be great to know some retired people that has a lathe.

Henry

[dieselfuelonly]

I picked up a few more parts from eBay, got a flywheel from a Deere with a Yanmar engine in it for real cheap.  Hopefully it will fit my engine, initially looking at the measurements it looks like it will, but won't really know until it shows up.  Picked up another stub shaft for the same model Deere so I'm hoping this could be a nice bolt-together setup.  Just waiting on parts to show up and we'll see.  By the time I'm all said and done collecting parts for this project I'll have enough to build two 

I am after a similar Stub shaft for my Kubota engines.

Anyone know of a source? I'm in Oz but are there any places like tractor joints or types of businesses likely to carry them.... at a reasonable rather than ridiculous price?

eBay has been where I've been having the best luck.  Since my engine is a Yanmar and many JD tractors had Yanmar engines it has been helpful to search for the Deere parts instead of Yanmar parts and that has opened up a lot more options.  If you could find out the applications your Kubota has been used in that may lead you in a good starting direction.  At least from what I've seen any dealer/manufacturer will charge a premium for parts like a stub shaft or flywheel... much much cheaper to go the used route or modify it to work if possible.

[Henry W]

Dieselfuelonly, that's great news! Let me know how it works out. I think there is a John Deere equipment graveyard on HWY 401 (Fayetteville Rd.) in Fuquay Varina. I was there years ago and they had everything imaginable. They did lots of work on compact tractors and turf equipment.
Having enough parts left over to build another one is good.

Henry W

[dieselfuelonly]

So if this information is useful to anyone, the engine I'm using is a Thermo King TK270M which is based off of the Yanmar 2TNV70 platform.  These are used in APUs on big trucks and can be got for pretty cheap used.  It seems that the John Deere part # AM875090 flywheel bolts up to either of these engines (the JD tractor this came off of had a 3TNA72 engine), and the stub shaft, JD part # M87178 _should_ be the perfect fit for this flywheel, will verify the fit and dimensions when it shows up.

Good news some of my eBay parts came in today and the flywheel will 99.9% be a perfect fit, will take it to work with me tomorrow where I have the engine and make sure.  But measured everything up for bolting the flywheel to the crank and it seems they are identical.  Ring gears have the same tooth count and I could even move the ring gear from my other flywheel to this new one if need be, but both are in good shape although the new one has slightly more wear.  New flywheel is thinner but that should make no difference for my application.





I ordered this stub shaft and realized afterward it's actually for something PTO related, but it looked nearly identical to the actual one I wanted so oh well.  The bolt circle and dimensions of it seem nearly identical to the actual stub shaft that is supposed to mate to the flywheel, although it has a machined area on the back where it must pilot into something for the PTO.  Looks like I could easily make it work, but the correct one is supposed to arrive by Wednesday so I will wait and see if that one is any different.  I'm hoping the mating surface is totally smooth so it completely sits down into the fingers on the flywheel that align it, which from the pictures on eBay I think it will, but its kinda hard to tell.

The outer end of the shaft is 1 3/8" I believe and the inner area with the keyway is 1 7/16".  I'd probably chop off the outer end of the shaft since the keyway doesn't run all the way down it.  However, I probably wont' end up using this one anyway.




Here are the pictures from eBay of the "correct" one I ordered.  Notice how the keyway runs the entire length and the mating surface of it appears to be totally flat without the piloting step machined into it.

If that ends up being the correct shaft, I will probably keep it at the full length as I could mount a serpentine pulley on the inner area to drive an alternator, etc., and use the outer end of the shaft to drive the LoveJoy to the generator head.  We will see what looks best when it arrives.

I'm pretty excited because it looks like this will all bolt up and end up being a LOT cheaper than having something custom machined.

It would also allow me to upgrade to the larger 3-cylinder Yanmar 3TNV70 / 3TNA72 (which the flywheel is from) / other similar engines which have more horsepower and could probably run the gen head at full output compared to my little 2TNV70 in the future if I wanted to.

[glort]

Contacted a place about a stub shaft for my Kubota. $239 + ( 10%) tax plus delivery.

I think I only paid $100 ea for the working engines. These things came with pulleys but you neve seem to find a used motor that still has them.
On top of this will be about another $100 For the taper lock pulley and then there are the belts.
Lot of money just for that side of things.

[playdiesel]

These type problems are why I own a lathe and mill

Good too see that you have sourced some usable parts. Used reefer engines are abundant, place near me has a semi trailer full. I am surprised that somebody has not produced a kit that converts them to other use such as you are doing.

[Henry W]

Contacted a place about a stub shaft for my Kubota. $239 + ( 10%) tax plus delivery.

I think I only paid $100 ea for the working engines. These things came with pulleys but you neve seem to find a used motor that still has them.
On top of this will be about another $100 For the taper lock pulley and then there are the belts.
Lot of money just for that side of things.

Everything went up in price. Not too long ago an SK style bushing could be purchased for around $20.00. Now it's at least double that price. That is a hefty price for a stub shaft. Kubota accessories and engine parts were cheaper than Cat or Perkins small diesels but they still cost  a good amount.

Paying a $100 for working engines is a bargain. If the engine is in good shape you will be saving lots. I think  purchasing a stub shaft for the price quoted is still ok since you paid a fraction of the price for the engines.

[glort]

Used reefer engines are abundant, place near me has a semi trailer full.

Wish I could find some at a decent price.  I'm really leaning towards the Kubota inline engines now which I think are all but the same as the Yanmars.
Just bought a little BX tractor with a Kubota and I love the thing same as the other one I have.  The engines alone fetch big money here but I'm thinking of trying to get rid of  a lot in the collection I have amassed over the years and put the money into one or 2.

I have a load of those garbage single vertical  Cylinder China copys of yanmars I bought cheap ( 8 of them I think) and I can't stand the racket they make and the ones I have had for some time have proven less than reliable and trouble free.  They do have a regular end crankshaft though which I spose is a Bonus but I can't think of much else to say for them other than I was able to pick them all up cheap.  I have some of the horizontal Cylinder Z type China engines and they are a world apart from the other Crappy Vertical Cylinder things but the ones I have are all aircooled. the Kubota singles  I have are watercooled but they are pretty noisy too by comparison to the inlines.

I have a couple of Ruggerinis, Lambardini's and a Hatz Verticle cylinder and they are all very good engines and miles away from the China vertical Crap.
When I do the big shed cleanout which I am preparing for atm, I think I'll pull them out and see what I can get for them. At least half the Chinas have never even been started up, still brand new.
They don't seem to be available on fleabay here now ( not much wonder why) so maybe, I might get something worthwhile for them?   I have a big 30 Hp aircooled twin ruggerini that's a real ball tearer with only 40 Hours on it but I would replace that with a Kubota too.  I was thinking of putting that in a small boat but I can't see that happening now and I have a 5 Cyl merc engine I was going to use for that anyway.

Spose I have really been gathering the engines waiting to see what sort of gen heads I can get but so far struck out on that front.
A 15-20 Kw 3 phase would suit me well.