I've been experimenting with the HEP and its effect on loco and passenger cars. It doesn't seem to have any effect, on or off, other than running sound. According to F40 manuals, isolating HEP or turning it off will put loco into variable RPM mode based on throttle.. the F40 is always in this mode. When HEP is activated and with Long Hood mode and AC on.. the loco should operate on a fixed RPM mode, with lever changing the electrical load not the RPM.. Also, with HEP off, there are still lights on in the passenger cars, and there is no indication that it's off at all.
You‘re talking about the classic F40s which used the prime mover for HEP generation. Both F40s in the game (Caltrain and MBTA) have separate HEP engines in addition to the prime mover.
Ah ok, that makes sense in how it operates. I was looking at the early model specs as well the the -2D for Via Rail, and they both had prime mover powered HEP, so assumed. Also, the versions for MBTA on the F40 wikipedia page mention only 2C, but in more detail on MBTA page, indeed shows 3C as rebuilt from 2C, which they originally used. Thanks for clearing it up. Now am curious to find correct manuals, if possible.
However, shutting down HEP ought to kill the lighting and A/C in the coaches, but apparently it doesn't.
Actually, I was going to update this, noting that it does seem to work. The interior lights do go out with HEP disconnected by either the AC on/off or shutting down generator. Can't vouch for the A/C temperature But, apparently there are small lights for the outside steps by the doors, which must be on an emergency or battery circuit on the cars, because these always stay on.
I think what AP is referring to is the fact that the early FP40s with prime mover-powered HEP had to keep the huge 645 running at 900 rpm just to keep the passenger lights and a/c going, even stopped in a station, and that turbocharger really does scream! With an HEP pony engine they can drop the big boy to idle.
Yea, the need for constant RPM on those was actually to maintain the constant AC 60Hz frequency for the house load. Any basic AC generator needs constant RPM. Big engines like that have very flat power curves, so can work find at constant RPM, losing just some efficiency. The power output is managed by fuel (as throttle in diesels is actually fuel increase not air).. so akin to giving less gas in your car on flats, and more on uphills while staying at same speed and gear. Keeps constant RPM.. With a separate HEP engine, the big mover can lower RPM when low load to get more efficient, lose less heat to friction and such and power up when more is required.. this akin to downshifting in your car on uphills for higher rpm where there's more power, and downshifting to lower the engine speed when not needed. More efficient. It's just that initially, all the documentation I found on the F40PH indicated a HEP generator connected to prime mover engine. Later was told here, about MBTA, and realized they mounted a Cummins genset behind the main engine for the rebuild of the 2C to 3C.
