MarkAlert,
You finally made me get out of my easy chair and go across the house and dig out my old but not very recently used Detrit Series 92 Service Manual. Carrying that load of bricks across the house was my exercise for the day.
From it I can tell that yours is an automotive engine, starter and oil cooler on opposite sides, left turning when viewed from the front end of the engine.
I can't find the designator for the specific model (the last 21) but I doubt that is important.
It was an interesting read that brought back good and bad memories. But, it is only a service manual and not an application guide so it did not specify rated HP's for the nose shaft.
What I did notice is that the only users of the front end of the crankshaft ever referenced in this manual were the fan, the alternator, and the A/C compressor. (The air compressor is gear driven on the other end of the engine in automotive engines - does yours even have an air compressor?)
Accounting for the HP's involved, I estimate (without any real mental effort or research - I'll leave that to you to chase up) ~ 25-30 HP for the fan, ~ 5 HP for the alternator, and ~ 10 HP for the A/C compresor.
I would note that it would be rare for all of those loads to be maxed out at once, although the larger 2 might - the A/C compressor and the fan might be working hard on a long hill climb for a truck or bus.
That said, being conservative, I make the nose shaft good for ~50 HP. But as I noted above, the last several Detroits I dealt with pulled 2 large fans, radiator and AC Condenser, an A/C compressor that was the size of small car engines (V-6) and an alternator as big as a WWII depth charge (well overstatement there, but it was 300 amp, however and the fan motors for the AC evaps were 80 amps each for two, so the constant electric load was significant) through a gear box that wasn't frictionless either, so I am sure those engines could have easily doubled the loads of the 3 mentioned above. As well, all those loads are 'soft start' meaning that they aren't instant on. Plus the coupling is rubber bushed further protecting the nose shaft from shock loads.
My gut tells me that your well drilling rig requires much more power than the designed 50 HP or even the 100 estimated HP on the coach class engines or someone would have selected some toy engine much smaller than this beast for the job. This is not a small engine. And, my gut also tells me that you are driving it all off the front of the engine.
I noticed something else. If you look at the two ends of the crank, the business end is a heck of a lot beefier than the nose shaft. That is for a reason. The flywheel end of the crank is designed to transmit HP's in the hundreds, well a couple or three maybe and the tiny nose shaft is good for a fraction of that or about 50 - 100 HP. The business end is also designed for someone dumping a clutch with a 80,000 lb load and the crank surviving even if it kills the engine.
If someone has applied this engine to drive a high HP load and maybe a high impact load off the nose end to keep from having to design a coupling for the flywheel end, or buy an opposite turning engine, then they have have done you a big disservice. And I believe that is what is going on here. Otherwise your engine code would have indicated a stationary engine designator.
If I have sized it up right, I believe you can continue to plan on broken cranks. Sorry.
rmw
