Don't think you have to log into Facebook to read this:
https://www.facebook.com/visitnctm/posts/742504241257321

They're basically going to turning it into a HEP cab car like Amtrak did for their 40th anniversary F40PH. Rumor is that Amtrak left the stack cover off and the engine seized up. Does make me wonder whether it would just be simpler to put in another 645 rather than gut everything and put in an HEP generator.

An actual and careful reading of the FB page explains that the purpose here is to provide head end power, and not propulsion. A 645 would be overkill; a skid mounted Cat or Cummins powered genset would be far more appropriate.

It depends on their needs and intentions.

Jim Wrinn and others were adamant, at the time it was acquired, that the F40PH needed to be saved as "representative American railroad history."

However, if NCTM needs a power car for its trips, and the 645 is damaged as alleged, it makes sense to retrofit a far more efficient HEP package rather than the one that was directly connected to the prime mover (and meant Amtrak and other F40PH's are remembered for HOWLING even as they sat in a station at what would otherwise be idle). The Grand Canyon Railway, the prime preservation user of F40PH's, have made this retrofit, along with freight gearing. I believe at least one outfit has made a HEP set that can be bolted right into the fittings for the 645.

The important question is whether they maintain the "original fabric" enough to restore it to more-or-less original condition later, or are they just going to "butcher" it? The former is a museum being practical; the other is a tourist railroad operation.

The F40PH does not run full speed in HEP mode, only HEP + traction mode. If they're not careful they're alter the weight distribution of the locomotive and make it ride real rough.

I don't think so. HEP at 60Hz requires that the alternator be turning at 720rpm (or equivalent) whether or not traction power is required. Since the diesel engine requires a considerable percentage of its fuel burn to maintain rotational speed, overall fuel consumption remains considerably higher than that of an 'equivalent' genset with a smaller modern high-speed engine. And not-so-incidentally this implies that the highest acceleration and load come with the engine governed at 720rpm -- notch access involving any higher engine speed than 720rpm is not available.

What is different is that the governor only commands fueling to hold the engine at 720rpm. If only the HEP load is imposed, the governor will only "add" fuel to hold the appropriate rpm as the electrical load changes.

It was fun to watch the governor adjust for commanded traction on the U34CHs at the end of a station stop -- the sound-pitch "note" of the engine would not change, but it would become deeper, throatier, and red laminar flame would rise up out of the stack... all at 720rpm.



There are actually two halves to this: that they'd change the weight distribution to load one truck 'unduly' more than the other, and that they'd reduce weight enough for the spring strength/rate or ride height to become 'improper'. (This latter point might be achingly familiar to those who owned 'Excalibur'-like conversions of Lincoln or Ford chassis -- which had a kidney-busting ride with very poor jounce response if the factory springs were left unmodified after the weight of the stock body components was removed.)

Both these concerns oughyt to be easily addressable if, as previously noted, the genset is built on a frame or skid corresponding to the 645 mounting points, and matches the balance fore and aft of the replacement -- easily enough approximated with four load cells under the corners of an assembled 645, if you don't have factory data.


On the other hand, presumably all the locomotives that were modified into 'cabbages' had these considerations taken into account in their rebuilding -- right??? -- and if NCTM wants some of the advantages of the 'extra carbody space' they could easily design the genset to fit in the rear of the carbody as some of the commuter railroads did, and use appropriate ballast elsewhere to balance the locomotive in the secondary springing.

I was right the first time. The F40PH has three modes of operation. The first mode NORMAL is the most familiar one, the locomotive runs the engine at full speed (893 RPM) It receives HEP power through the head end generator and controls train speed by varying the excitation of the magnetic field in the main AR10 generator. The second mode is STANDBY which provides HEP only and no traction, in this mode the engine turns at lower speed (720 RPM) and the head end power is generated by the main AR10 generator instead of the separate head end generator, while the F40PH is a DC locomotive the AR10 main generator is still a three phase AC generator It is just rectified using diodes for DC traction power. The last mode is ISOLATE where the locomotive runs like a standard freight locomotive where the engine speed varies with throttle position, in this mode a ultra low 260 RPM idle stage can be activated.

This arrives at a time when I am discussing the F40PH with several others who were involved in the original design and delivery. I might offer some comments later, or maybe not. Meanwhile, does anyone know the actual maximum HEP load of the museum train at their ambient temperature and passenger capacity extremes?

PC

If you removed the 645 and AR10 and all related machinery and put a typical commuter rail 500kW HEP set on the 645 engine mounts, the resulting unit would be about 55,000 lbs. lighter than an Amtrak F40PH, and could be up to 14,000 lbs. misbalanced front to rear (lighter on the rear truck) prior to making any weight distribution corrections. The weight of each machinery item is published in the service manual, and you can closely calculate the beam loading distribution from a general arrangement drawing with dimensions.

PC

A relatively cheap 'alternative kludge' would be to ballast the locomotive after the genset installation is done, using a couple of scales to watch the weight on each truck. I suspect the weights could be made using cement loaded with steel-mill-slag aggregate or actual scrap, in relatively impromptu molds not 'part of the historic fabric' other than proper anchoring.

Resist the temptation to go for lighter weight while forgetting that ride height affects coupler height.

Just to "complete the circle" on the F40PH, I am recording here that this evening I packed and addressed the last of the classroom reference notebooks prepared by two of the three EMD instructors who presented the F40PH classes to the customers. Those materials are being sent to the Barriger Library.

PC