why not frieght locos??

[UPRR engineer]

I was talking about SD70's and GE AC's from like a few years ago, the regular freight gearing wont hold you back from being able to reach high speeds.

[carnej1]

I've heard of super speed freights, usually intermodals like the Super-C, so I'm guessing that there are freight engines that can give a good run with speed.  The lower gear ratio is for I guess the term is lugging. 

 You're right...in fact both ATSF and UP had significant numbers of secong generation road units geared for high speed fast freight service. Santa Fe bought F45s (SD45 with an aerdynamic cowl) specifically for that kind of train.

[trainfan1221]

I've heard of super speed freights, usually intermodals like the Super-C, so I'm guessing that there are freight engines that can give a good run with speed.  The lower gear ratio is for I guess the term is lugging. 

[UPRR engineer]

A passenger locomotive and a freight locomotive of approximately the same horsepower will have the following differences:

Different gear ratios, freight power will generally have lower top speed....

Just because the gears are different, doesnt mean road units wont go really fast. Dont go thinking they wont get up above 75 because of it. I've had a broken speedometer a time or two and ran her as fast as she'd go, thats how i know they'll do it.

[wjstix]

Pulling the train isn't really the issue, technically any engine could be used to pull a passenger train (assuming it could go fast enough to meet the schedule.) As has been mentioned it's really an issue of being able to supply head-end electrical power or in older times steam to the passenger cars. Even in steam locomotive days, not all steam engines had the connections to supply steam to the passenger cars, only engines used in passenger service (although some switchers had steam connections so they could provide steam to warm up cars before the road engine was coupled up).

Steam was used for heating and cooking in the cars...electricity was from batteries carried by each passenger car. So when passenger diesel "E" units came along in the 1930's, they had steam generating boilers in them so they could provide steam for the cars. F units could be ordered with steam generators, usually in "B" units. Many early F units were built as A-B units with a drawbar between the two units, since the B unit didn't have a cab it had room for the boiler and water tank(s).

E-units could be used on freight service, such as fast freights. But because their center axle was an "idler" (unpowered) they weren't very good at slow speed / heavy drag freights, they were designed for high speed operation.

Great Northern and other roads developed "heater cars" that could be used to provide steam heat to passenger cars, both as a supplement to existing passenger engine's steam heat, and so that a non-boiler equipped engine could pinch-hit on a passenger train.

[CSSHEGEWISCH]

In the pre-Amtrak pre-HEP era, it was not unusual for an otherwise standard freight locomotive to be equipped with a steam generator and signal lines for occasional or regular passenger service.  N&W and GTW both used GP9's regularly on their mainline passenger trains and D&H had RS2/3's pulling their passenger trains.  Rock Island used to have a real hodgepodge pulling its suburban trains, RS3's, BL2's and H15-44's among other things.  Monon had two of its C420's equipped with steam generators to handle the Thoroughbred in its last days.

In the mid to late 1960's, there were several passenger locomotive designs that were little more than modified freight locomotives.  GE had the U28CG and U30CG, EMD had the SDP35, SDP40, SDP45 and FP45, and Alco offered a steam generator option in the C420, C628, C630 and C636.

[trainfan1221]

EL put displaced E units into freight service, I think they had to be re-geared.  Generally a passenger locomotive is one a little more streamlined but that is not always the case.  NJT has GP40s with generators added and lets not forget the monstrous U34ch, which was a freight locomotive used on commuter trains but set up so it could be converted to freight use.  In steam days passenger engines had larger wheels so they could have more speed, I think the trade off was less power or torque fron the smaller wheel radius on freight engines.

[daveklepper]

A passenger locomotive and a freight locomotive of approximately the same horsepower will have the following differences:

Different gear ratios, freight power will generally have lower top speed, also lower minimum speed, and consequent higher tractive effort before electric motor overload.   The frieght locomotive can start a heavier train and the passenger operate safely at higher speed without motor damage.

The passenger locomotive will have head-end power capability, supplying electricity for passenger train heating, air-conditioning, and lighting.   Possibly cooking and refrigerating as well!   The freight locomotive will not have this equipment.  In the old days it was steam producing boiler that heated and in some cases even powered air-conditing, but that is history except on tourist operations.  In those days some railroads did buy locomotives with steam boilers intended for both services, the Boston and Maine and the Norfolk and Western are too excellent examples.   B&M GP-7's and RS-3's, and N&W GP-9's and GP-18's.

The passenger locomotive will be equipped with some communications between a conductor in the coaches and the engineer.  The freight locomotive may possibly be equipped with radio control of distributed power, a remote control locomotive or locomotives somewhere in the middle of the train.

[carnej1]

back in the day (1950s) they did use e and f units for freight service didnt they??

 EMD sold F units for both freight and passenger service from the introduction of the FT(day one). The E units were designed and marketed as passenger engines but by the 1960's/70's there were a number of railroads which would press them into freight service if they were short on power (Erie Lackwanna comes to mind). Bt then there had been significant declines in passenger service so in some cases the E's were surplus power.

[ndbprr]

The eaasiest explaination is trucks are trucks and cars are cars.  Can you haul stuff with cars? Yep.  Could you ride in a semi?  Yep  Do you want to do that? Nope.  Same with locomotives to a degree.

[UPRR engineer]

I'll have look next time i see it.

[Dakguy201]

The UP has several cars fitted with generators to supply head end power to its passenger fleet -- one goes with each consist.  In general, it will be the first car after whatever engine they are using, but anytime you catch an office special standing still, you will be able to identify which car has the generator by the noise and the large vents along the side of the car.

[UPRR engineer]

where???

 http://cs.trains.com/forums/ShowPost.aspx?PostID=1427814

Right there, if thats what ya ment. 

 

[UPRR engineer]

Any kind of locomotive can move a passenger train, theres something called HEP, headend power, which sucks electicity from the locomotives to power the cars. I dont know how they get power to the cars on something like the UP passenger specials, must have some kinda MU cable that plugs into the unit and then into the car, or maybe they get power themselves as the wheels roll using a generator????

[wisandsouthernkid]

where???

[wisandsouthernkid]

back in the day (1950s) they did use e and f units for freight service didnt they??

[UPRR engineer]

Reason i was asking, your air brake question, "....in great detail". One guy did some typing about how it works, i found you a good place to get information.

[carnej1]

 Amtrak bought a large fleet of SDF40s early in it's existence(1970's). These were essentially SD40-2s with aerodynamic cowling. They had a series of derailments (at the time blamed on the six axle trucks though since then other theories have gained credibility) and all were retired very early.

 The simple answer to your question is that locomotives are designed for the service they will be used in and what works well for a light,short,fast passenger train may not be the best thing for a long heavy freight train.

 There are exceptions though. The Alaska RR uses it's SD70MAC's to pull seasonal passenger trains. Also during the 1960's a number of railroads bought essentially standard road units with steam heating equipment for passenger service (SDP35, SDP40, U28CG). They did this knowing that the locomotives could be used in freight service with little or no modification once passenger service ended....

[wisandsouthernkid]

sorry never got stopped for that, now i will yes! thanks for the catch, sorry everyone

[UPRR engineer]

Are ya gonna thank us if we answer your questions? Noticed your not too good at doing that, least ya could do, i think.

[wisandsouthernkid]

why cant they use freight locomotives on passenger lines like why cant amtrak use an sd40 instead of an f40 or something of that nature and why not an e9 for freight use??