The loading rate is governed by how fast the diesel engine handle increasing fuel rates. A four cycle with a free wheeling turbo has terrible turbo lag. You have to very gradually increase the fuel to allow the turbo to keep ever so slightly ahead of the load without smoking.
The two cycle EMD isn't as slow because it's turbo gets a boost from the gear drive - actually, the exhaust energy at the lower notches isn't sufficient to provide enough scavenging air for the engine. It HAS to have a gear driven blower. Still, it's about 20-25 seconds to full load from idle.
I have heard that nuclear power plants using Alco engines to run emergency cooling pumps can get up to full load in about 15 seconds. They used stored compressed air to spool the turbo up.
The practical limit on acceleration on a passenger train is 0.1G. For locomotive hauled trains this is rarely a problem since the locomotive's adhesion won't allow acceleration that great with more than a couple cars at any speed or horsepower.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
I was aware that the Metra F40CH-2 was programmed to load slowly until the train speed increased to where tractive effort no longer exceeded the adhesion limit. This was to prevent damage from wheel slip and keep a constant engine speed for hotel power. I was told the loading took 30 seconds.
The constant-speed engine would not work with a slip/adhesion control.
The calculations Paul M made for a 410-ton, 4,300-hp train resulted in a speed of 58 mph after a minute and tractive effort of ~27,000 lbs. The train attained 17 mph after 12 seconds before maximum tractive effort fell below the adhesion limit of 72,000 lbs. Taking a minute to load up would reduce tractive effort and acceleration appreciably, resulting in a much lower speed and distance after a minute. The lower speed would allow more than 27,000 lbs starting TE.
Someone may ask why not load up faster? On level track, 15 seconds may be possible; but even flat-land railroads have slight grades and the occassional hill. Being the standard system power that can be assigned to mountain-crossing trains, a much lower load-up is a practical compromise.
I very much agree that a light weight locomotive is needed for fast passenger train service. Mechanically the LRC was the equivalent of the MLW C-638, yet weighed under 240,000 lbs, similar to the EMD F-series. One source quoted only 210,000 lbs.
Notwithstanding crumple zones and safety cages, I'd prefer to see a raised cab like the Turbo Train, early City of Denver, Danish and Japanese regional trains.
That a locomotive can take 60 seconds and not even be close to full HP is something I had never accounted for in simulations I hade run. That GE units were that slow to load is something I was not aware.
Why I had originally asked the question is that in response to one of the proposals for LD service, I remember a friend in an advocacy group reacting to "only one locomotive on a train." I got to wondering whether Amtrak was putting more power on trains as an engineering factor-of-safety to compensate for their level of failures on locomotives, rather than in response to the type of simulations Don Oltmann is talking about.
Metra runs 11-car commuter trains with a single F40, but it seems an 11-car train on Amtrak runs with a pair of P42's. about double the tractive effort and 3 times the HP. Did Amtrak ever get any "unit reduction" with the higher HP P42's, say, a pair of P42's replacing 3 F40's in the Mountain West?
I am not talking about underpowering train or overloading locomotives, but when a "standard" corridor consist has a P42 and 4 Horizon cars, you are talking 1000 HP/car which is Japan Bullet Train level of HP (OK, the Bullet Train is MU so it doesn't have the weight of the locomotive and NPCC unit, but 4000 HP on a 4-car train is a lot of power).
If you have a pair of P42's on an LD train, from a HP perspective that is like a brace of 5-6 F units. Do they really need that much power since apart from AutoTrain Service, 12 cars is a common LD consist? Or is the second locomotive and "insurance policy." And if they need that much insurance against breakdown, what does that say about the locomotives or their maintenance procedures -- a Diesel-electric locomotive is mature tech by now.
If Amtrak needs a minimum 2 locomotives on an LD train, if they need a locomotive at one end and an NPCC on the other end for corridor trains, perhaps if they ever shop for new locomotives, they should look for something in the 2000-2500 HP range. Perhaps something like an 8-cyl GEVO, and perhaps something a lot lighter weight for reduced axle loading so it could be run faster on tilt trains without spreading the rails, which limits speed on the F59's used with the Cascades Talgo. I am thinking along the lines of the original LRC locomotive or the FM Speed Merchant as a lower-HP lower axle-loading unit.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
I think the only way to accurately assess HP requirements for train service is to do a series of simualtions over the route and compare running times. Then, plug the various running times into the ridership model for the route and equipment utilization and employee productivity models for the service and see what the overall effect is.
There is certainly a point of diminishing returns, but it is likely route specific.
One thing not talked about much is the speed which the locomotive loads. On a LD train, with stops every 40 miles or so, it doesn't matter much if the locomotive gets to full load in 20 seconds or 90 seconds, but for shorter hauls, it can be a factor. GE locomotives can take up to a full minute before they are even at 1/3 of max HP. EMDs are typically at full HP after 25 seconds or so.
HarveyK400 I ran across something years ago that referred to Amtrak performance standards for acceleration and braking. I remember an acceleration curve where a train would attain roughly 75 mph in a mile on the way to at least 125 mph for both diesel and electric. Because of the distance covered at faster speeds, ~95 mph was reached in 2 miles and ~110 mph in 3 miles. This is pretty quick and explains the seemingly extravagant use of power as a general practice, and the number of units at least previously "required" for a train. How arbitrary is such a standard; and what went into it? More relevant, is this rate of acceleration justified for most regional "day train" services, or can a significant fuel savings be obtained? It's not just recovering speed after station stops, but after curve and zone reductions, and after meets. By comparison, I think it was Paul M that calculated a P42 with six Horizon cars could attain 110 mph in 4-1/2 miles.
I ran across something years ago that referred to Amtrak performance standards for acceleration and braking. I remember an acceleration curve where a train would attain roughly 75 mph in a mile on the way to at least 125 mph for both diesel and electric. Because of the distance covered at faster speeds, ~95 mph was reached in 2 miles and ~110 mph in 3 miles. This is pretty quick and explains the seemingly extravagant use of power as a general practice, and the number of units at least previously "required" for a train. How arbitrary is such a standard; and what went into it?
More relevant, is this rate of acceleration justified for most regional "day train" services, or can a significant fuel savings be obtained? It's not just recovering speed after station stops, but after curve and zone reductions, and after meets.
By comparison, I think it was Paul M that calculated a P42 with six Horizon cars could attain 110 mph in 4-1/2 miles.
Your comments about needed acceleration and attainable speed is a good question. It is a reason why I am not that rah rah in favor of many calls for high speed rail. Too often it is over kill when there are numerous stops in short distances. Commuter rail is certainy ruled out but that's where you hear the cry for speed most often.
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Back to the years of the HEP changeover 75-80 roughly Amtrak used converted baggage cars with two Detroit V-12 71TT (Twin Turbos) rated at 750 HP Each if old memory serves me right they were rated at 550 KW each unit, two to a baggage car and were designed to phase both gensets to feed power to the train. We also had a few E-8-E-9 Locomotives equipped with the same HEP power packages. I was standing in New Haven, Ct. station when a broken down E-60 electric hauled by a hijacked Conrail SW-1500!!, arrived with an Amtrak train of 18 new Amfleet cars....temp outside was 5 degrees above zero...off came the dead power. Train was WAAAAY behind schedule...in backs two E-8 locos of which only the rear engine had operational HEP both of which were running with the power circuit breakers open. Coupled to train and hooked up HEP and the Electrician closed the breaker which showed only 300 KW's on the meters on the control panel. Both engine blew copious amounts of blue smoke until the combustion chambers warmed up under load (common). The electrician noted until the train started to depart the Kw's increasing as a single brakeman on the train started at the rear of the train and walked car to car turning on the hvac heating system on each car which is the overhead heater/AC units one to each end of each car. By the time the train was on the old NH Shoreline he reached the last car and turned on it's heating system. The turn on one car at a time was to avoid overloading the generators. Each Amfleet car could pull on power up a continuous 85 Kw's per car at maximum draw quickly overloading the HEP generator breakers.Once power was up and the cars systems turned on slowly as the systems powered up and reached operating temperatures the current demand dropped off.
I used to work train 60-61 The Montrealer Penn station to New Haven off the spare board and while checking the HEP car before departing Penn Station one night Noted an average of 225-2275 KW's power flow to the train combo amfleet/Heritage cars totaling 19 cars that night running on ONE generator...the other generator was shutdown but serviceable.
The MBTA in Boston used to use ex GM&O F-3 locomotives rebuilt as FP-10's with a Cummins 450 HP 6 cylinder engine hooked up to a 335 KW generator...back then it was SOP to turn the heating system on each car one at a time by one crew member to avoid triping out the HEP. Once all were on there was no problem unless the HEP failed.
Amtrak F-40PH's the first 30 units numbered 200-229 had 500 KW HEP installed which drew 700 HP off the prime mover leaving 2300 HP for traction to move the train..roughly the power of an E8. Later ones have as stated before 800 KW HEP units installed which use at max load 1100 HP off the prime mover. keep in mind this HEP load varies constantly. As an Engineer myself if I needed an extra 700-1100 HP to get over a mountain POOF!!! Off goes the HEP until I get to the top at which point a push of the button restores power to the train.
Another point where Amtrak over designs is the air compressor on each EMD engine. They use the optional 6 cylinder 400 CFM compressor, the standard is a 3 cylinder 254 CFM unit which is more than enough. The E units used a 2 cylinder 90 to125 CFM compressors on each engine. The 400 CFM unit was a lot of extra weight and Normal 0 MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} unnecessary capacity. Amtrak trains use a train lined main Normal 0 MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} reservoir air line but remember the HEP..turn it on and the prime mover winds up to 897 RPM and the air compressor is driven of the crankshaft
The only locomotives Amtrak had that "disobeyed" the one loco per HEP rule were the P30CH's. They had a pair of engine gen sets in each and could train line to other units. The trick is to bring the gen sets online in phase with the other already on line. Lots of icky electrical gear, particularly back in the "old days". If you bring the generator online out of phase - BANG!
I once saw a pair of P30s hauling an excursion of 19 Amfleet around the Horseshoe Curve.
jkeatonisn't there also the issue of how many HEP cars each HEP locomotive can supply?
Somebody said in the US an 18-car passenger train has always? had to get all its HEP from one unit, even if the train has two or three units. On rare occasions F40s have pulled 18-car trains-- to Seattle Seahawks games, if nowhere else-- so maybe 800 kW is enough. But HEP demand will depend on weather...
Here are two a sample videos of LIRR with two locomotives on seemingly short six-car trains.
http://www.youtube.com/watch?v=-_QhDyFYW34
http://www.youtube.com/watch?v=u6ZX3IdzqPE
Oops, and did I say pantographs and LIRR? I meant to say "I am stupid." And I don't really think of "locomotive" to be exclusive of electric service.
With HEP, isn't there also the issue of how many HEP cars each HEP locomotive can supply? When VIA is running the peak season Canadian (or specials like its Veterans Train of three years back), there is a 8 cars per F40 limit, and a maximum train length of 24 cars and three F40s, due to HEP power requirements and the limits on how much pass-through current each car can carry.
I know the export equivalent of the F40 that EMD sold to Ireland's railways has had a dismal failure rate, mostly due to HEP problems, and those engines have been repeatedly derated, from seven to six to five HEP cars per engine.
Jim in Ottawa
European freight trains are also appreciably lighter than comparable North American equipment. A European freight train of 2500 tons is considered heavy.
Maglev "North American railroads need heavier engineering than European designs" That is because our trains run into cars all the time! And most of that danger is from idiots, and apparently there are fewer of them in Britain.
"North American railroads need heavier engineering than European designs"
That is because our trains run into cars all the time! And most of that danger is from idiots, and apparently there are fewer of them in Britain.
Never too old to have a happy childhood!
No, I didn't realize the DM30s were at each end of the train...only zipped by them a few times. I have ridden behind the diesel single units from Babylon/Patchougue to Montauk, Ronkonkoma to Greenport, Huntington Sta. to Port Jefferson, LIC to Jamaica (Lower Montauk train: best railfan ride in NYC), and Jamaica to Oyster Bay.
henry6I don't believe the LIRR is doing that today...nor did they do it before.
The LIRR used to run 17 car trains on the North Shore with a single 2400 HP CLiner - albeit some of the coaches were 60 footers. Every day. Day after day. On time.
I don't believe the LIRR is doing that today...nor did they do it before. They did have a locomotive, usually on the east or outbound end of a train, with a control cab dummy (unit with only controls, no eingine or traction motors) on the other, west or inbound, end of the train. But that was back in the late 60's into the 80's in general. Today, there may be some circumstances when two units are on a train, but rarely. Electric service does not need a locomotive unless dual powered diesels from non electrified terminals like Port Jefferson and Montauk. Most diesel trains have but one unit in regular service today.
I think it's notable that the LIRR often uses two locomotives, one on each end of the train, on its electrified routes. I'm not sure if it's to avoid turning at Penn Station, for horsepower reasons, for reliability reasons, or to avoid "gapping." In the videos I see the pantographs are up on both locomotives.
Maglev "North American railroads need heavier engineering than European designs" That is because our trains run into cars all the time!
That is because our trains run into cars all the time!
Not quite, at least not the whole reason. Basically our system developed with heavier horsepower, higher speeds, larger demensions and weights in the course of time, plus the safety issues. This just adds up to heavier specifcations in the long run. At least that's the way it was explained to me.
That is because our trains run into cars all the time! And most of that danger is from idiots, and apparently there are fewer of them in Britain. The doors on the Intercity 125's were manual, and open outwards. There is not enough crew to watch every door at stations, so impatient pasengers sometimes swing the door open and jump onto a crowded platform from a moving train. In some societies on this planet, the population knows how to look out for itself!
A note on HEP -- the AC on the Intercity 125's seem prone to failure or (efficiency / laziness shutdowns...); but it was usually sufficient to open the Dutch door window. The Southwest Chief does not have this option for cooling!!
"Make no little plans; they have no magic to stir men's blood." Daniel Burnham
I had a conversation about a year ago with a vice president ot Ahlstom and asked about such technology here. His reply was that North American railroads need heavier engineering than European designs and much cannot be economically applied here. This included diesel multiple unit as well as dual mode locomotives. That is one reason why we don't have such equipment, trains, or service here.
While traveling Britain, diesel multiple unit trains were a very common consist. The idea of "a locomotive in every car" is another modest, inexpensive, off-the-shelf solution. These trains often ran at 70 mph, which is after all the Acela's scheduled speed on the NEC.
Didn't the British HST have a mid-train locomotive, turbine power, and tilting? None of it worked.
Indeed , I brought up the Intercity 125's because I think they would be a good solution for American trains. Keep it simple, without fancy tilting mechanisms or some unproven propulsion; keep it lightweight; and add the reliability of two locomotives. Also, since our trains keep running into things, maybe the idea of a locomotive at each end is good for safety? Aren't two low-horsepower prime movers safer in a crash than one big, heavy engine?
Part of it is locomotive reliability, part is Amtrak's skimpy maintenance, and part is HEP. Figure HEP is consuming about 700 - 800hp. on bigger trains like the EB, CZ, or SWC. Also all P42 have a common gearing, good for 110 mph. This is good on the few routes where it can be utilized, but less than ideal on western transcon services. Also on many services if you lose the power on your only locomotive you lose the heat in winter and cooling in summer for your passengers, could be dangerous. Having to add freight locomotives to replace failed Amtrak locomotives is guarranteed to loose time due to slower speed gearing, very rare for a freight locomotive to be geared higher than 70 mph.
The "best" diesel-locomotive hauled passenger train I ever rode was powered by two locomotives, one at each end of usually five to seven-cars. They were called "Intercity 125" for the railroad and maximum speed, and operated over much of British Railways at over 100 mph schedule times.
I realize that there is a lot more to the planning and execution of a corridor train service than train sets, but were Amtrak to go with something like the Intercity 125 (that is, a low weight, low air drag Diesel train based on off-the-shelf technology) for the next generation of corridor fleet, I think it would help the cause and long-term growth of passenger service immensely.
Keep in mind that the crown jewel of the British HSR effort was the APT (Advanced Passenger Train) to which the HST (High Speed Train) -- the Intercity 125 -- was only meant as an interim measure. The APT ran into a slew of teething problems with its active tilt suspension, and the HST proved to be "good enough" to be the premier train and to cancel the APT.
Of course, there are probably a number of ways to mess up the acquisition of such equipment, foremost being the FRA strength requirements. The other way to mess this up is the "shame factor", that we would be implementing the technology of Mother England from 40 years earlier. This business of feeling shame for what the Japanese were doing led to the Metroliner being overspeced (i.e. made overweight, overcomplicated, and over prone to mechanical failure) for 160 MPH operation when it would realistically do 120 MPH in service, followed some years hence with a similar exercise in national pride and design-by-committee with the Acela.
locomotive gearing may be a factor for the higher the gearing the less torque. Now that may be less for ac traction motors but that is out of my area of knowledge. Any one have infor??
DMUinCT In the interest of Long Locomotive Life, where goverment funds for replacements may not be coming --- Is it better to use One locomotive running at 100% of output or Two locomotives running at 50% of output on a train? From a useful life, Two would be better, drawbacks, more maintenance checks and a little more fuel used with Two.
In the interest of Long Locomotive Life, where goverment funds for replacements may not be coming ---
Is it better to use One locomotive running at 100% of output or Two locomotives running at 50% of output on a train? From a useful life, Two would be better, drawbacks, more maintenance checks and a little more fuel used with Two.
Of course in normal operations a single unit operating at 100% with a 0% failure history and designed for the train at hand is ideal After that it is what the masters decide will do the job with what they have.
The "best" diesel-locomotive hauled passenger train I ever rode was powered by two locomotives, one at each end of usually five to seven-cars. They were called "Intercity 125" for the railroad and maximum speed, and operated over much of British Railways at over 100 mph schedule times. By using two relatively light-weight locomotives, the trains had extra acceleration out of staions and faster speeds on hills. I read recently that a replacement for these trains was unpopular, and that the old trains were back in service.
From Wikipedia:
"...Experience with the high-speed Class 55 Deltic locomotives had shown that a low axle weight was essential to avoid damage to the track at sustained high speed, and that high-speed engines were the only way to provide a good enough power/weight ratio for diesels. To power the HST at up to 125 mph, each locomotive had a new diesel engine, the 12-cylinder Paxman Valenta, running at 1,500 rpm and developing 2,250 bhp. The 70-tonne weight of the locomotive gave it a 17.5-tonne axle loading.
The prototype train of seven coaches and two locomotives was completed in August 1972. By the autumn it was running trials on the main line and in May 1973 the prototype, now designated Class 252, set a world diesel speed record of 143.2 mph (230.5 km/h). The concept was proved during trial running between 1973 and 1976, and British Rail decided to build 27 production HSTs to transform Inter City services..."
Don U. TCA 73-5735
Yes, heaven forbid if an Amtrak train tied up a busy freight railroad so that merchandise get waylayed someplace short of its destination. But also, Amtrak does not necessarily have a full engine house at the other end of the run so there is no change of power, second locomotive is definitely needed in case of trouble. I would also add the lack of turning facilities at far end of trip but two unit Amtrak trains are often elephent style so that factor has to be discounted.
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