MARC To Purchase Siemens Chargers?

[MCL1981]

I get everything you just said other than load balancing propulsion. How does having two MP36s not dramatically increase the propulsion power?

[F-line to Dudley via Park]

I get everything you just said other than load balancing propulsion. How does having two MP36s not dramatically increase the propulsion power?

No. The MP36's rate of acceleration is capped by the gearing, not the power plant. And the MP36 has pretty crummy starting acceleration compared to the GP40's they replaced. The difference is once they get to a certain speed they kick into high gear and run at much higher top speed, which the Geeps couldn't do. You could lash up 4 of them together and the wheels on the traction motors wouldn't spin any faster any sooner than one MP36 does now. You can re-gear them for more nimble acceleration out of a dead stop--that matters a lot more at commuter rail stop spacing--but it comes at the trade-off of lowering the top speed. You've got one performance range to tweak around with, and that's it. The Chargers, being way more powerful, are *supposed to* (<-- emphasis on the unproven) be able to rev up faster. Which is why MARC is buying them instead of clogging the Penn Line with more MP36's. But it's still a far cry from what an HHP-8 can rev.

The "more power" issue is all about HEP. You can pull a monster consist weighted down with standing room-only human flesh just fine with the propulsion...if the passengers don't mind sitting in the dark with no climate control. The horsepower is overkill for propulsion alone. But the more of that horsepower that gets siphoned away as HEP by the electricity demands of all those coaches, all those HVAC units heating/cooling stuffed cars with frequent door openings, all those gadgets plugged into the electrical outlets...the more the propulsion suffers by having its share of the total power infringed on. The double-loco boosts the HEP so the propelling loco can single-task, the HEP loco can single-task, and the whole consist wastes less energy compartmentalizing the relative strain that gets put on the power plant(s). It doesn't make anything go faster. It prevents performance degradation when a single engine is so overloaded pulling out of a dead stop that it nearly has a heart attack. But it's not like lashing up a freight consist where there's no HEP anywhere and each extra loco is pure, unadulterated propulsion power. Albeit, unadulterated propulsion that serves the same "it's not faster...it's just less slower" purpose under escalating load.

[electricron]

No. The MP36's rate of acceleration is capped by the gearing, not the power plant. And the MP36 has pretty crummy starting acceleration compared to the GP40's they replaced. The difference is once they get to a certain speed they kick into high gear and run at much higher top speed, which the Geeps couldn't do. You could lash up 4 of them together and the wheels on the traction motors wouldn't spin any faster any sooner than one MP36 does now. You can re-gear them for more nimble acceleration out of a dead stop--that matters a lot more at commuter rail stop spacing--but it comes at the trade-off of lowering the top speed. You've got one performance range to tweak around with, and that's it. The Chargers, being way more powerful, are *supposed to* (<-- emphasis on the unproven) be able to rev up faster. Which is why MARC is buying them instead of clogging the Penn Line with more MP36's. But it's still a far cry from what an HHP-8 can rev.

The "more power" issue is all about HEP. You can pull a monster consist weighted down with standing room-only human flesh just fine with the propulsion...if the passengers don't mind sitting in the dark with no climate control. The horsepower is overkill for propulsion alone. But the more of that horsepower that gets siphoned away as HEP by the electricity demands of all those coaches, all those HVAC units heating/cooling stuffed cars with frequent door openings, all those gadgets plugged into the electrical outlets...the more the propulsion suffers by having its share of the total power infringed on. The double-loco boosts the HEP so the propelling loco can single-task, the HEP loco can single-task, and the whole consist wastes less energy compartmentalizing the relative strain that gets put on the power plant(s). It doesn't make anything go faster. It prevents performance degradation when a single engine is so overloaded pulling out of a dead stop that it nearly has a heart attack. But it's not like lashing up a freight consist where there's no HEP anywhere and each extra loco is pure, unadulterated propulsion power. Albeit, unadulterated propulsion that serves the same "it's not faster...it's just less slower" purpose under escalating load.

All what you stated applies to a locomotive - like Amtrak's Genesis- where propulsion and HEP are powered from the same diesel and generator/alternator. But does it apply also apply where propulsion and HEP are powered from different diesels and different generators/alternators within the same locomotive - like what I believe a MP-36? I don't think so.

[F-line to Dudley via Park]

No. The MP36's rate of acceleration is capped by the gearing, not the power plant. And the MP36 has pretty crummy starting acceleration compared to the GP40's they replaced. The difference is once they get to a certain speed they kick into high gear and run at much higher top speed, which the Geeps couldn't do. You could lash up 4 of them together and the wheels on the traction motors wouldn't spin any faster any sooner than one MP36 does now. You can re-gear them for more nimble acceleration out of a dead stop--that matters a lot more at commuter rail stop spacing--but it comes at the trade-off of lowering the top speed. You've got one performance range to tweak around with, and that's it. The Chargers, being way more powerful, are *supposed to* (<-- emphasis on the unproven) be able to rev up faster. Which is why MARC is buying them instead of clogging the Penn Line with more MP36's. But it's still a far cry from what an HHP-8 can rev.

The "more power" issue is all about HEP. You can pull a monster consist weighted down with standing room-only human flesh just fine with the propulsion...if the passengers don't mind sitting in the dark with no climate control. The horsepower is overkill for propulsion alone. But the more of that horsepower that gets siphoned away as HEP by the electricity demands of all those coaches, all those HVAC units heating/cooling stuffed cars with frequent door openings, all those gadgets plugged into the electrical outlets...the more the propulsion suffers by having its share of the total power infringed on. The double-loco boosts the HEP so the propelling loco can single-task, the HEP loco can single-task, and the whole consist wastes less energy compartmentalizing the relative strain that gets put on the power plant(s). It doesn't make anything go faster. It prevents performance degradation when a single engine is so overloaded pulling out of a dead stop that it nearly has a heart attack. But it's not like lashing up a freight consist where there's no HEP anywhere and each extra loco is pure, unadulterated propulsion power. Albeit, unadulterated propulsion that serves the same "it's not faster...it's just less slower" purpose under escalating load.

All what you stated applies to a locomotive - like Amtrak's Genesis- where propulsion and HEP are powered from the same diesel and generator/alternator. But does it apply also apply where propulsion and HEP are powered from different diesels and different generators/alternators within the same locomotive - like what I believe a MP-36? I don't think so.

It adds considerable weight and fuel consumption to the locomotive as a direct tradeoff, and reduces the size of the fuel tank. The no-generator version of the MP36, the MP36PH-3S, weighs 280,000 lbs. and has a 2500 gallon tank. The MP36PH-3C clocks in at a morbidly obese 295K (I think only the dual-mode ALP-45DP is heavier) and loses 750 gallons of fuel storage while consuming a lot more fuel. Its tweaked cousin, the MP40PH-3C, does 4000 HP, is geared to accelerate faster, and sort of splits the difference on fuel capacity...but its top speed is capped lower. The lineup is boxed in to this narrow performance range because of all the power consumed lugging its own bulk around. Tweak the gearing to accelerate better...but forget about running on Class 6 track, or accelerate like a staggering drunk but hit triple digits. Right now the MP36 is is the highest-speed diesel on the market that meets TIer 3 compliance and has a generator. All of the known Tier 4's in development are alternator-based. All of the >4000 HP locos are alternator-based. All of the locos that do 110 MPH or better are alternator-based. I don't think there are any generator-based Tier 4's of equal-or-better power in development that will be available for order before 2020.

So no...there is no way to take a pick-your-poison choice of 1) mediocre accelerating, or 2) mediocre top speed and make it high-performance through power chaining. The gearing sets the parameters for everything you attempt to chain, and it's a narrow range of parameters because of the bulk and all the components competing for more share of that bulk. The Charger--an no-generator make--is only supposed to weigh 264K for its 4400 HP prime mover, very large 1000 kV HEP output (12 Amfleets), 2200 gallon tank, 125 MPH top speed, and zippy acceleration that blows the '36 away. MPI's alternator-based HSP-46 manages 4600 HP (1000 more than a '36), 600 kW of HEP, a 2000 gallon tank, and way zippier gearing for a 90 MPH max speed (i.e. a much wider range of starts vs. max speed gearing configurations to play with vs. very limited range with the '36s). The HEP output is overkill on these makes despite presence of the alternator, but if you have a consist so gargantuan as to require a double-draft it'll cost less and lug less deadweight to lash up two of those vs. two obese generator-equipped units. It's not clear if you can really raise the ceiling on HEP generator makes and hit that Tier 4 compliance with the inferior weight and fuel consumption bogging everything down, and accomplish all that while raising the bar netting high-performance acceleration and top speed. The '36 is the best it gets in the generator dept. for anything that's going to be available the whole rest of the decade. And it's not good enough to do what's being asked these last few posts re: chaining for higher performance. It's not a high-performance locomotive. It's too bloated to be one, boxed into too many tradeoffs to be one. That's why MARC's buying Chargers for the Penn Line. It'd be a lot less stupid if they bought Sprinters, but at least they aren't klutzing up the NEC with slovenly '36s for the next 20 years and making the despairing Amtrak dispatcher start drinking on the job.

[chrisf]

Right now the MP36 is is the highest-speed diesel on the market that meets TIer 3 compliance and has a generator. All of the known Tier 4's in development are alternator-based.

What? EMDs have used alternators since the GP/SD40 series was introduced in the late 1960s. Do you mean DC traction motors vs. AC traction motors? Edit: maybe you mean HEP inverters vs. standalone HEP alternators? There's a whole lot of this post that makes no sense whatsoever.
The MP36PH-3C does not use a generator either for traction or HEP.

[chrisf]

The double-loco boosts the HEP so the propelling loco can single-task, the HEP loco can single-task, and the whole consist wastes less energy compartmentalizing the relative strain that gets put on the power plant(s).

In general, this is incorrect. When two, properly functioning passenger engines are on an Amtrak train, for instance, one provides HEP+traction and the other provides traction. One isn't simply there to provide hotel power to the train.

[Backshophoss]

Both versions of the MP-36 use a AR-10 based Main Alternator,you lose HP to the rail with static inverter for HEP
generation,with the separate HEP (Cat powered Genset)almost all the power from the Main Alt goes to the rails.
Sometimes it depends on how the Prime Mover is setup and Fuel used(regular diesel or Bio-diesel blend).

[chrisf]

I get everything you just said other than load balancing propulsion. How does having two MP36s not dramatically increase the propulsion power?

It would, significantly. The engines would be MU'd together, same as freight engines. There's no "load balancing" going on.
Amtrak isn't sending 15-16 cars on the California Zephyr over the Rockies with only one engine pulling.

[F-line to Dudley via Park]

Right now the MP36 is is the highest-speed diesel on the market that meets TIer 3 compliance and has a generator. All of the known Tier 4's in development are alternator-based.

What? EMDs have used alternators since the GP/SD40 series was introduced in the late 1960s. Do you mean DC traction motors vs. AC traction motors? Edit: maybe you mean HEP inverters vs. standalone HEP alternators? There's a whole lot of this post that makes no sense whatsoever.
The MP36PH-3C does not use a generator either for traction or HEP.

I'm talking about both and probably not separating them out well enough, which is why it may be confusing (sorry...not a born gearhead, just stayed at a Holiday Inn Express last night trying best to accuracy-check those posts using the board search function ).

1. AC traction motors, not DC
+
2. HEP inverters vs. standalone HEP generator
+
3. What's available or in development now that meets Tier 3/4 regs
=
The MP36PH-3C and MP40PH-3C are currently the most powerful passenger diesels on the market or in (known) development that have a separate HEP generator (Cat C-27...only the MP36PH-3S omits that). All upcoming product with more horsepower and/or more wattage of HEP power to give like the Charger, HSP-46, F125 are inverter/no-generator. Nothing generator-based has so far been rumored in development, so from now through at least until 2020 the MPxxPH-3C is the highest-performance make a commuter rail operator can buy that has a separate generator. The Tier 4 regs contribute to that situation; trying to get around the weight and fuel consumption penalties of carrying around the separate generator has manufacturers going inverter-only as path of least resistance.

The MPxx's performance range is gearing-related; MPI offers them with gearing configurations for zippier acceleration at penalty of lower top speed (GO's order of MP40's), or higher top speed but clunkier acceleration (MARC's order of MP36's). Because they are so heavy, it's hard to wring more performance out of them by simply packing more raw HP into the prime mover or raw output into the generator; something has to give to make it fit. As is, the generator vs. no-generator and 3600 HP vs. 4000 HP variants trade off higher vs. lower fuel capacity to stay within weight. So MARC doesn't have a lot of swell options for Penn Line-appropriate power if they insist on the separate generator, because they already have the make that's as good as it's going to get. Their wiggle room for making those things perform any better is limited to changing the gearing...i.e. forgoing triple-digit speeds to accelerate faster out of a dead stop.

Double-drafts and multiple lash-ups aren't going to do the trick making everything go faster when the wiggle room is gearing. Until some builder figures out a cost-effective way to shed a few dozen tons of bulk by other means there's not going to be a purchase option that meets all of the following--1) accelerates faster, 2) does >100 MPH top speed, 3) has more total HEP output, 4) has league-average or better fuel tank capacity, and 5) meets Tier 4 regs--that retains the separate HEP generator. So MARC's buying Chargers--alternator-only out of the factory--and not fussing around with more MP36's for the Penn Line.



^^I dunno...does that--missed left turns in Albuquerque and all--get to the original question well enough?

[dowlingm]

Here is GO 647, their MP40 repowered/reworked into an MP54AC with the HEP generator replaced with inverter HEP.
https://www.wabtec.com/uploads/MP54_QuickSpec_B.pdf" onclick="window.open(this.href);return false;

[MCL1981]

I'm still lost on this.

The way I'm reading this, an MP36 has so much power, that it's already accelerating as fast it possibly can. As such, lashing up a second MP36 provided no increase in acceleration at all. That would tell me that an MP36 running alone with no cars at all will accelerate just as fast as a fully loaded 8 car Penn Line train at rush hour. Really? How is this different than a freight train that has 4 to 6 locos dragging it around???

Slightly unrelated question, can two locos supply HEP at the same time? I'm guessing you can't just parallel two 480v generators and call it a day, so how does it combine HEP power, if it even can?

[Backshophoss]

Only 1 MP-36 can supply HEP,there's no proven method to sync multiple inverters or HEP gensets together
at present.

[MCL1981]

Only 1 MP-36 can supply HEP,there's no proven method to sync multiple inverters or HEP gensets together
at present.

I didn't think so. So why then would there ever be more than 1 MP36 on a Penn Line train? If it can't add more acceleration, and it can't add more HEP, what is it besides dead weight???

[electricron]

I didn't think so. So why then would there ever be more than 1 MP36 on a Penn Line train? If it can't add more acceleration, and it can't add more HEP, what is it besides dead weight???

It adds more horsepower so the train can have more cars.
I'm not familiar at how much longer Penn Line trains are in comparison with Camden Line trains - but I'll assume those it more than one locomotive are longer.
A MP-36 has an EMD 16-645F3B diesel with 3600 horsepower, and a MP-40 has an EMD 16-710G3B-T2 diesel with 4000 horsepower, capable of pulling 12 double level coaches (per GO Transit).

As an aside, the F59PH GO is retiring has an EMD 12-710G3A diesel with 3000 horsepower, which GO reports was capable of pulling 10 double level coaches.

Taking those data points further, does that mean a MP-36 can pull just 11 double level coaches?

Don't confuse pulling power with acceleration or speed.
A Mack semi tractor truck with 605 horsepower can pull 40 to 50 tons of weight in its trailer, but that doesn't mean it accelerates faster or runs at a faster speed than a Chevy pickup truck with just 420 horsepower.

[MCL1981]

I'm still not seeing how going from 3600 HP to 7200 HP doesn't allow it to accelerate faster. Each one has half as much weight to accelerate from a stop.