Erratic performance from AC units on poor rail conditions? I never knew that.... With the craziness of Colorado's weather, (now knowing the above)I find it interesting that the Moffat Route is powered almost solely by AC locomotives. Thanks for a great explanation. I'll re-read it tomorrow, when my gray matter isn't quite as frazzled!
Since the higher factors of adhesion of modern locomotives are acheived by more accurate control rather than brute-force engineering, they're less reliable. (IIRC, simply rebuilding an old engine with microprocessor control - no change to the traction motors, engine, overall weight, or anything else relying on simple mechanics rather than information - increases its factor of adhesion, though not to the level of a new locomotive.) In short, the smaller the factor of adhesion you rely on when designing an engine, the more reliably it will perform as claimed.
I just caught a train at the New fallbrook yard that had something like 5 engines including at least one Gevo. Way overpowered. Maybe that's were the DPUs are. Overpowering tains from San Diego. Also, for the past month or two, the yard power here has been 2 GP60Ms and what looks like a Dash-8B though it's hard to tell. Seeing a high HP unit sitting around the yard occurs regularly, but not often. Usually it's GP30s,35s,39ms. Couldn't those units be used with a single DPU unit mid train? Seem like a waste of high HP units.
We had 8.1HPT on the SPOEVE today, boy did we fly over Stevens! There are lots of SD40's in storage in Seattle right now, so I do not think they are to short on power. Kevin
UP assigns GP60s to locals and AC6000s to rock trains. I think these are more signs of the disfavor these units are held in than of what service they're suited for. Downgrading engines often puts them in service they aren't adapted for. When I think this, I always think of PRR electrics. After experiments showed the O1 (2-B-2 wheel arrangement) was too slippery, their plan was to use the P5 (2-C-2) for passenger and the L6 (1-D-1) for freight. After making the P5s but only a couple L6s, they made the GG1s for passenger, pushing the P5s to freight. The P5's wheel arrangement was designed for speed, not adhesion. I don't know if this caused problems in service. The PRR had no large class of purpose-built freight electrics until the E44.
But BNSF also still runs those same GP60s out on the Transcon. Are the purging all the mid HP GPs? Those 60s have to be wasting more gas.
We still get the GP60/M/B on trains in the NW, they are normaly trailing units. They have a good rep (as most high HP 4 axle units do) for slipping but a old head engineer told me the other day as long as you have a 6 axle in front of it it will dry the rails for it and they work pretty good then. I have never been on a train where they gave us problems. Kevin
I feel like the Transcon guys down here liked them except for the rough ride. It's always interesting to read the various opinions on different types of units. As I've said before, sometimes the Yard will run them up front for old times sake. Back before the Empire (builder) ate up everything good an right in the southwest.
I've caught GP60s on BNSF rock trains theu Sherman- even got a GP60M-GP60-GP60M set on a NB empty. But, BNSF has a tendency to put whatever they can find on rock trains, from SD40-2s to Dash 9-44CWs to any 4-axle power. A rock train is a far cry for a Super Fleet-painted GP60M originally used on Transcon pig trains....... On CSX, C60ACs are used in just about every type train there is, except for locals- at least from what I've seen on the Fitzgerald Sub. On UP's Chico Sub (ex-RI) in Texas, GP60s have been used semi-regularly as rock train power.
