Slow down to 540 rpm

[contaucreek]

Hi gang. Was at my local John Deere dealer picking up my new mower and I saw a used PTO genny sitting there, 10,000 watt requiring 540 rpm PTO speed. Was thinking of a driveshaft assy to feed it off the CS' crankend but dont know if the engine can safely be taken down to that rpm. Obviously my hp would be compromised and the resulting efficiency of the genny derated accordingly (2500 watts ?). Any thoughts on the speed change ??

              ps- no word from the engine shop yet re head and cylinder.

[oliver90owner]

Depends on efficiency of the gearbox.  Tractor driven, so not a prioity probably. 

540RPM is shown on the power graphs for the engine so no problems running at those speeds.

I have a 4kw (I think) unit which will be tagged onto the CS at some point.  I would not expect more than a couple kW at tops, as the engine would be down to less than 4 1/2 H at that speed and the gearbox losses will be about the same (as it is still at rated speed).

In your instance a 12kW (or more) box will be losing a large % of your power, so I wouldn't expect much more than 1 1/2 kW, especially running a 10kW genny at 15%, what with cooling fan losses, excitation,etc with it being way off it's most efficient mode of operation.

Those boxes are often grease lubricated, BTW

In a nutshell - a waste of time in my view.

Regards, RAB

[rcavictim]

In my limited experience the gearboxes on the tractor driven PTO generators are really lossy.  It takes an enormous amount of horsepower merely to spin one up to speed with no electrical load.  I have a 27 kW continuous rated Generac  job here that I am testing off my Changfa 1115 engine.  I am using V-belts.  The gearbox on this PTO (shud more appropriately be referred to as a POS) machine runs 160 degrees F hot even with thin 50 weight gear lube in it and the most power I've tried to get from it is about 4 kW.  I don't think most of these are made for the long haul either.  The only ones I've seen use a 2-pole, 3600 RPM head on them.  That design favours spinning itself to death early either into a fuzzball inside of exploded armature windings (Generac 's have a reputation of doing this and I've seen the results first hand), or bearing failure.

IMHO your efficiency will be higher with v-belt drive to an 1800 RPM, 4-pole head than to a PTO/POS drive 3600 RPM genny.

[contaucreek]

Hey victim, it is a 3600 jobby. Will I see you at any of the engine shows this summer??

[rcavictim]

Hey victim, it is a 3600 jobby. Will I see you at any of the engine shows this summer??

I rest my case.  Are you the fella from Marmora area I met at the Cookstown smoke show last summer?  I may make it to that one again this year but have no plans to attend any others.  I don't travel far any more and have to put all my meager resources into survival systems now like my wind turbine, not superfluous travel and vacation entertainment.

I just got the latest Ontario Hydro bill for my shop meter.  Last month (trying to conserve) I used a total of $20 worth of electricity.  On top of this O.H. is charging me $90 to deliver it and other fees for a total bill of over $120.  I am so angry I almost cannot speak.  I have had enough of this crap.  Those jokers should all be put in prison!!!!  I won't even mention the house meter.     Yes absolutely, my wind turbine is my numero uno priority project this summer.