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Re: In Which We See What The F125s Look Like...
Author: SP5103
Date: 02-01-2015 - 10:58
Some comments about this -
First, this is the first rail application I am aware of for the Caterpillar C175-20 engine though the C175-16 is used on the NS PR43C. This appears to be a new size/design of engine and not an upgraded 3500 series and way too small for a 3600. This will be a fertilizer engine using DEF/urea which isn't as big of an issue for a captive service locomotive. After the 20-645 fall from grace and the 20-710 not catching on (at least in rail service), one wonders if it is that wise to return to the 20 cylinder concept.
Another issue is that North American passenger/commuter locomotives have gotten "fat". The mandated buff buff and cab strength all add weight, as does the HEP system and now there is there is the emissions equipment. Most now have a dynamic brake section more typical of a 6-axle unit. The high speed dynamic brake uses something similar to extended range but instead of low speed it uses the extra grids and fan at high speed and to be able to self load at full horsepower. Weight has been an increasing issue with 4-axle units way back to Santa Fe's GP60M and all of 4-axle FP series resulting in those designs being limited in fuel tank capacity which now has to be split with DEF. And now the commuter agencies want AC drive with its attendant weight. It will only be a matter of time before they are forced into an A1A-A1A configuration or they wise up and put a smaller engine on each end which gives them some redundancy and solves the cab car issue.
The Wikipedia article is slightly misleading the weigh it is written suggesting that the F125 is something EMD offered and Metrolink is the first buyer. In fact it was put out to bid by SCCRA/Metrolink with the specification written by their consultant STV. It was to be one of the first Tier 4 commuter locomotives and the prime mover and horsepower rating were left up to the bidder/builder as long as it met the performance requirements. The F125 is based on a common design specification that most of the commuter agencies and Amtrak came up with a few years ago (its nickname escapes me something like Prius?) but is a custom design for Metrolink. I don't think they specified 125 mph except for the current HSR craze as Metrolink currently doesn't have anything over 90 mph and most of their track is far less. Most of the Amtrak or Metrolink units currently in service could be regeared to 110 mph so there really isn't that big of an issue.
Do remember that the tractive effort generated on a diesel-electric is in proportion to speed, so about a 20% increase in speed from 90 to 110 mph would require more than a 20% horsepower increase considering that train resistance also increases with speed.
And all of this is not cheap - and they are spending taxpayer (mostly federal grants?) money to do it. Several years ago an MPI MP40 went for about $3.5 million (with every order becoming more customized due to customer consultant demands). If you look at the Metrolink contract the F125s will cost them around $6 million dollars each. These aren't standard designs that can have the engineering costs shared over several orders, the customer pays for it.
First, this is the first rail application I am aware of for the Caterpillar C175-20 engine though the C175-16 is used on the NS PR43C. This appears to be a new size/design of engine and not an upgraded 3500 series and way too small for a 3600. This will be a fertilizer engine using DEF/urea which isn't as big of an issue for a captive service locomotive. After the 20-645 fall from grace and the 20-710 not catching on (at least in rail service), one wonders if it is that wise to return to the 20 cylinder concept.
Another issue is that North American passenger/commuter locomotives have gotten "fat". The mandated buff buff and cab strength all add weight, as does the HEP system and now there is there is the emissions equipment. Most now have a dynamic brake section more typical of a 6-axle unit. The high speed dynamic brake uses something similar to extended range but instead of low speed it uses the extra grids and fan at high speed and to be able to self load at full horsepower. Weight has been an increasing issue with 4-axle units way back to Santa Fe's GP60M and all of 4-axle FP series resulting in those designs being limited in fuel tank capacity which now has to be split with DEF. And now the commuter agencies want AC drive with its attendant weight. It will only be a matter of time before they are forced into an A1A-A1A configuration or they wise up and put a smaller engine on each end which gives them some redundancy and solves the cab car issue.
The Wikipedia article is slightly misleading the weigh it is written suggesting that the F125 is something EMD offered and Metrolink is the first buyer. In fact it was put out to bid by SCCRA/Metrolink with the specification written by their consultant STV. It was to be one of the first Tier 4 commuter locomotives and the prime mover and horsepower rating were left up to the bidder/builder as long as it met the performance requirements. The F125 is based on a common design specification that most of the commuter agencies and Amtrak came up with a few years ago (its nickname escapes me something like Prius?) but is a custom design for Metrolink. I don't think they specified 125 mph except for the current HSR craze as Metrolink currently doesn't have anything over 90 mph and most of their track is far less. Most of the Amtrak or Metrolink units currently in service could be regeared to 110 mph so there really isn't that big of an issue.
Do remember that the tractive effort generated on a diesel-electric is in proportion to speed, so about a 20% increase in speed from 90 to 110 mph would require more than a 20% horsepower increase considering that train resistance also increases with speed.
And all of this is not cheap - and they are spending taxpayer (mostly federal grants?) money to do it. Several years ago an MPI MP40 went for about $3.5 million (with every order becoming more customized due to customer consultant demands). If you look at the Metrolink contract the F125s will cost them around $6 million dollars each. These aren't standard designs that can have the engineering costs shared over several orders, the customer pays for it.
