Stand alone power source for PTO generator

[Nicetoy]

I have a 80 something hp naturally aspirated Mercedes Diesel that is a miser fuel wise, and a **** good motor. I also have a 25K PTO generator. I typically run the generator off my Ford 1710, which works, however the tractor is slightly underpowered for the generator. Under heavy loads the tractor is strained to the point where the output voltage drops and some stuff doesn't run well, and puts a stress on motor loads in my house. That said, most of the time, everything works as it should and there is no problem. BUT. I am moving to a new property soon, and would like to keep my little tractor for doing strictly tractor related stuff. So i'd like to weld together a trailer and mount the Mercedes Diesel on it with a PTO shaft to the generator. My question to those smarter then I, What would I need to use in between the engine and generator to produce 540RPMs or 1000Rpms? I cannot just weld a pto shaft onto the flywheel and go, or can I? Any ideas?

 

[Mickey_Fx]

More important than how to mount a shaft to the flywheel, what are you going to do for a governor to control engine speed as loads vary?

 

[kevinwak]

You can get a bell housing to bolt to the flywheel that has a clutch in it and an output shaft for stationary use. That is how it was done on my Dads sawmill that I worked at growing up. You then connect to the input shaft of what you want to run with belts and pulleys in the right sizes to give the speed you are after. It might be harder to find one that bolts to a Mercedes engine, but they sure were easy to get and plentiful for the old Detroit diesels that we ran.

Sent from my iPhone using TractorByNet

 

[Nicetoy]

Like my tractor, I rev it up to a point where it is putting out the full 240V as tested on a meter, then just leave it running at that engine speed, there is no governor, and that is why I have a voltage drop when heavy loads are put to it because it is underpowered. To get full output, WinCo says you should have a 50hp tractor, so I'm thinking that with a 80-90 hp stand alone engine, even when loads are put to the motor, it should be way more engine then needed, and absorb those loads seamlessly.

 

[Nicetoy]

I know it can be done with belts and pulleys, I was trying to stay away from things that wear over time and crack.. Was looking more at some type of gear driven solution.

 

[Willl]

there is no governor

Sure about that ?

 

[Nicetoy]

I suppose I'm not sure, but there are no electronics of any kind on the tractor, so it would have to be something mechanical, likely part of the injection pump if anything, The mercedes also has zero electronics, and is 100% mechanical, which is why I want to use it.. Trying to keep this as simple as possible, something that can be parked in the barn, and pulled out and start right up.
.

 

[joshuabardwell]

I suppose I'm not sure, but there are no electronics of any kind on the tractor, so it would have to be something mechanical, likely part of the injection pump if anything, The mercedes also has zero electronics, and is 100% mechanical, which is why I want to use it.. Trying to keep this as simple as possible, something that can be parked in the barn, and pulled out and start right up.
.

Governors can absolutely be mechanical. Remember the two ball mechanism where as the motor spins centrifugal force raises them and conservation of angular momentum slows them down, and vice versa? I love that thing.

EDIT: This thing:

I'm not literally suggesting that such a thing is inside your Mercedes, just that an analogous mechanism could be.

 

[Nicetoy]

I have to imagine the mercedes motor has something built in already?

 

[unimog_jason]

There are couple engines I can think of that this might be:

OM312 - 6 cylinder truck engine, 5.1 litres displacement - very old engine, not likely.
OM314 - 4 cylinder truck engine, 4 litres displacement - somewhat common engine, used in vans, Unimogs, tractors and likely boats.
OM352 - 6 cylinder truck engine, 5.7 litres displacement - very common engine, used in Unimogs, MB trucks, tractors, boats, etc.
OM617 - 5 cylinder car engine - 3 litres displacement - common as dirt.

If you have one of the truck engines and it happened to come out of a Unimog or boat you're in luck, it will have the right governor and flywheel housing for your application. You can either buy an over center PTO kit and bolt it up to your engine and devise a system to step down the shaft speed to 540 RPM or remove the reduction gearbox from the generator and directly drive it (assuming you have a 4 pole generator that turns 1800 RPMs and not a 2 pole @ 3600 RPMs). Lastly you can look at buying something like this and bolt it directly to the engine:

Generator Alternator Head 184E 23KW 1 Phase 120 240V SAE 4 6 5 Stamford Type | eBay


If the engine came out of a truck or van it will have a different flywheel housing and the governor will not likely work very well for you. If it came out of a car your out of luck on both counts and you're likely better off looking elsewhere.

Jason

 

[Nicetoy]

The engine is a OM617 naturally aspirated from a 300D, I already have the WINCO 25K Pto generator so, I have both, I was thinking I wouldn't need the governor because the motor would be much larger then the max needed to run that generator so likely after the engine is set at the appropriate RPMs, any load change wouldn't have an effect on the motor that would drop the voltage enough to hurt anything. I could be way off here. All I was thinking was that if I have the engine running at 3000rpms, how do I step that down to 540 or 1000 rpms

 

[smiley]

I'd think about using a Mercedes transmission with belt/pulley or chain/sprockets on the output shaft. Standard trans in low gear would give you a huge reduction in rpm's and be more trouble free in the long run but Auto should work. There are cruise controls available that use a signal pickup on the driveshaft that should control rpm's within an acceptable range. I've got an old Rabbit diesel I've been thinking about for the same application.

 

[Mickey_Fx]

Like my tractor, I rev it up to a point where it is putting out the full 240V as tested on a meter, then just leave it running at that engine speed, there is no governor, and that is why I have a voltage drop when heavy loads are put to it because it is underpowered. To get full output, WinCo says you should have a 50hp tractor, so I'm thinking that with a 80-90 hp stand alone engine, even when loads are put to the motor, it should be way more engine then needed, and absorb those loads seamlessly.

You do NOT set engine speed for generator usage with a volt meter. Engine speed controls A.C. freq. Induction motors, what you will find most commonly around the house are sensitive to being run at correct freq. Conventional electric clocks will NOT keep accurate time if freq isn't correct. You also may have other things around the house that are sensitive to A.C. freq.

 

[RickB]

You do NOT set engine speed for generator usage with a volt meter. Engine speed controls A.C. freq. Induction motors, what you will find most commonly around the house are sensitive to being run at correct freq. Conventional electric clocks will NOT keep accurate time if freq isn't correct. You also may have other things around the house that are sensitive to A.C. freq.

In my experience, the frequency and voltage of most generators is more or less linear. Setting voltage will yield acceptable frequency, and vice-versa.

 

[zzvyb6]

If your motor and transmission was equipped with cruise control, then it could be adapted to deliver an engine rpm which produces the proper 'pto' rpm. I have a 3:1 gearbox that I use on my lawnmower to reduce the high speed pto down to 540 for my WinPower alternator.

You would just need a tailshaft-to-gearbox adaptor to complete the system.

 

[unimog_jason]

An OM617 won't work for you unless you can figure out a way to strap an external governor. Surplus Center used to have them but it looks like they sold out. Even with an external governor it may not work all that well, I've owned a great many OM617s and none of them had great throttle response. If you can't overcome that limitation you're going to see some pretty serious voltage and frequency drops when a big load kicks in.

Jason

 

[smiley]

You would just need a tailshaft-to-gearbox adaptor to complete the system.

I just used the transmission yoke and universals with a short piece of the drive shaft and turned a plug/ short shaft with sprocket in the back end, into a pillow block, for a skid steer I built years ago.

 

[BHD]

can the gear box on the generator be taken off and just direct drive it, (most likely it is a 1800 RPM generator), or contact the company and see if they will sell you a plain end plate with out the step up gearing,

most generators that bolt direct to the engine are called single bearing units, as they only have one bearing in the generator/alternator and the engine end of the unit is supported by the motor,
belt drive and PTO have two bearings, so there should be a shaft in or behind the gear box to direct drive (with out gearing)

modern generators, have voltage regulators, and adjust the input voltage to keep the output voltage at a given rate,
the cycles, HZ, is set by RP Ms, 1800 RPM for 4 pole, and 3600 for 2 pole, the governor is used to keep the engine running at a set RPM, (they can be mechanical or electronic) the range of droop should be with in 3%),


Many electronic items need to be keep fairly close to the 60 cycles or they may be damaged, (as time clocks and other things are many times work off the cycles, and motors need the cycles to keep the speed correct. under or over will create heat.

the generator in the picture, I made the bell housing to mate the generator to the engine, using a flex plate to drive it, (like a auto matic trasmision uses)

If a two bearing I would suggest most likely a chain coupling, or some type of coupling that alows some flex in it,

 

[joshuabardwell]

In my experience, the frequency and voltage of most generators is more or less linear. Setting voltage will yield acceptable frequency, and vice-versa.

They really have to be, right? Since you can't modify the spacing of the heads on the rotor. But I think the point is that most electrical equipment is more tolerant of variation in voltage than frequency, so if your generator is not perfectly calibrated to deliver exactly 60 Hz / 120 V, it's better to get the frequency dead-on than the voltage.

 

[RickB]

They really have to be, right? Since you can't modify the spacing of the heads on the rotor. But I think the point is that most electrical equipment is more tolerant of variation in voltage than frequency, so if your generator is not perfectly calibrated to deliver exactly 60 Hz / 120 V, it's better to get the frequency dead-on than the voltage.

My point was that Mickey was incorrect. His contention that setting output by measuring voltage would disregard frequency is flat wrong. Setting output with a simple VOM is far better than relying on a series of indicator lamps or an analog gauge on the generator head. Checking frequency establishes a finer level of accuracy, but is not independent of voltage.