how do the railroads decide which engines to use and how many,and how do they decide what engines are facing which direction.for example if you have a manifest train going to wherever usa there might be fourengines and onemight be facing one way the others another way how do they decide this?is it just random or is there a method for this.i know it may be a dumb question but hey we all gotta start somewhere and ive always been curios about it
how do they decide what engines to use
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actually, the dead power isn't THAT common, it's more to allow for the train to be split and head to 2 different cities independently.
You're right Ken, I forgot about splitting the consist.
When I mentioned the dead units I had VIA's Churchill train in mind as they often freeze up and have problems in the winter.
Actually not only ALCO but EMD as well.
UP ran the GP7s long forward...at the time it was thought to be for safety reasons for the crew in the cab. Take note of the steam engines cab in the back for some of the o'l timer hogs this was a natural thing when the diesels came on the scene to run long hood forward. (but then there was this steam engine...Baldwin had the SP AC12 Cab forwards...lol...an odd ball...what fun!)
nope, and remember, there are no stupid questions. We've had a few stupid answers over the years, tho.........and more than a few from me probably....
unlike a car, the power and/or speed of a locomotive isn't any different going forward or backward. A car is geared so that reverse is very low, you just can't go (well, normal folks can't) 70mph in reverse. A locomotive doesn't have the gearing issue since the traction motors (electric motors on each axle) have the same power regardless of which way they turn.
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kenw
5th Generation Texian
often the last unit is rear-facing so that it can lead on the return trip. If it isn't the rear unit, at least one in the consist will usually be rear-facing so that it can be moved (via passing sidings or whatever to the front on the return trip.
I once watched a crew take a SD40T-2 out of the middle, take it to a not-too-distant wye and turn it simply because it had the only working air conditioner in the bunch.
I once watched a crew take a SD40T-2 out of the middle, take it to a not-too-distant wye and turn it simply because it had the only working air conditioner in the bunch.
Rico
BN Modeller
Josh and Ken are both right.
The railways use a formula to match the right HP with the tonnage. There is a rating to ensure the power can pull above and beyond the load and also handle any grades or sharp curves along the route. There is a combined tractive effort that comes into play: let's say one loco can pull 50 cars, two together may be able to pull 120. Sounds weird doesn't it?
As for the type of loco sometimes they use whatever is available and sometimes they add locos that are headed to the same destination. I've seen -9's on branch service pulling four cars as that was all that was available. We've all seen six or more locos on short freights as some were in transit and handled dead in the consist.
Direction usually doesn't matter on a mainline between larger cities as long as the lead loco faces forward. On a branch without a wye one usually has to face the opposite way for the ride home but there are exceptions. It's not uncommon to see a single loco running in reverse, I've done it but it's a bit of a pain in regards to visibility.
Passenger trains often run elephant style (all facing forward) so that a dead loco can be swapped out if need be. Amtrak or VIA rail is a prime example, again there are exceptions.
The railways use a formula to match the right HP with the tonnage. There is a rating to ensure the power can pull above and beyond the load and also handle any grades or sharp curves along the route. There is a combined tractive effort that comes into play: let's say one loco can pull 50 cars, two together may be able to pull 120. Sounds weird doesn't it?
As for the type of loco sometimes they use whatever is available and sometimes they add locos that are headed to the same destination. I've seen -9's on branch service pulling four cars as that was all that was available. We've all seen six or more locos on short freights as some were in transit and handled dead in the consist.
Direction usually doesn't matter on a mainline between larger cities as long as the lead loco faces forward. On a branch without a wye one usually has to face the opposite way for the ride home but there are exceptions. It's not uncommon to see a single loco running in reverse, I've done it but it's a bit of a pain in regards to visibility.
Passenger trains often run elephant style (all facing forward) so that a dead loco can be swapped out if need be. Amtrak or VIA rail is a prime example, again there are exceptions.
NYC_George
Well-Known Member
RS-3's long nose facing out
When I worked for the railroad in the late 60’s and early 70’s all our RS-3’s both freight and passenger were run in pairs long noses facing out. The Harlem Division was considered a branch line to the Hudson so RS-3’s were the biggest freight engines we had. If there wasn’t enough FL9’s to go around for passenger service and you had only one, the whole train would just go around the loop at Grand Central Station.
NYC_George
When I worked for the railroad in the late 60’s and early 70’s all our RS-3’s both freight and passenger were run in pairs long noses facing out. The Harlem Division was considered a branch line to the Hudson so RS-3’s were the biggest freight engines we had. If there wasn’t enough FL9’s to go around for passenger service and you had only one, the whole train would just go around the loop at Grand Central Station.
NYC_George
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kenw
5th Generation Texian
actually, the dead power isn't THAT common, it's more to allow for the train to be split and head to 2 different cities independently.
kenw
5th Generation Texian
As has been pointed out, how many engines is determined by the weight of the train and the terrain it needs to traverse. As far as direction, it's largely determined by which way they were facing when needed. The exception would be the first and last engine in a set......and then only if the train is going "out and back" in which case having a cab forward engine on each end makes things nicer for the crew. I was on a tour of MRL facilities a few weeks back, and watched them turn an engine on their turntable to hook to the end of a helper set headed for Bozeman pass. They obviously wanted it facing a certain direction.
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Rico
BN Modeller
You're right Ken, I forgot about splitting the consist.
When I mentioned the dead units I had VIA's Churchill train in mind as they often freeze up and have problems in the winter.
Alcomotive
Grandson of an ALCO Builder
Actually not only ALCO but EMD as well.
UP ran the GP7s long forward...at the time it was thought to be for safety reasons for the crew in the cab. Take note of the steam engines cab in the back for some of the o'l timer hogs this was a natural thing when the diesels came on the scene to run long hood forward. (but then there was this steam engine...Baldwin had the SP AC12 Cab forwards...lol...an odd ball...what fun!)
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i know that was probably a stupid question as there are a ton of experianced railworkers on here but i was always wondering that,to be honest i figured the number of units had something to do with weight,grades or even adding extras just to have more braking but i thought direction had something to do with some traction ormula or something
Direction doesn't have anything to do with any formula used to calculate how many engines are needed on a train. The direction the locomotives face in a consist are given in many of the answers above, most of which are for the convenience of the crew or for safer operations when the train would be involved in dropping off or picking up cars. You need as many engines (or horsepower) to move a train regardless of which direction the cabs are pointed.
kenw
5th Generation Texian
nope, and remember, there are no stupid questions. We've had a few stupid answers over the years, tho....
.....and more than a few from me probably....unlike a car, the power and/or speed of a locomotive isn't any different going forward or backward. A car is geared so that reverse is very low, you just can't go (well, normal folks can't) 70mph in reverse. A locomotive doesn't have the gearing issue since the traction motors (electric motors on each axle) have the same power regardless of which way they turn.
Laidoffsick
3 Railer
Well on the BNSF, the Power Desk takes care of that. They tell us exactly what units and how many units to use on each specific train. FRA inspection comes into play as far as where the engine needs to be for its inspection, and then if an engine is due for a major service, it goes to wherever the GE or EMD service facility is. In southern CA, its either LA or Barstow.
Number of units is based on HPT (horse power per ton)For example a Z train is usally rated at 3.5-4.0 HPT (again determined by the power desk)so divide the train tonage by availble horsepower.
Dash 9's = 4400 horse power
train tonage for example 5000 tons
So.... 4 units = 17600 horsepower/ 5000 tons = 3.52 HPT
Now if you want to know your speed up Main 1 in the Cajon Pass....
6.23 x 3.52 hpt = 21.9 mph .... so if you're under 22 mph (which is great speed) then 1 of your units is weak
The engineer is responsible for maintaining that scheduled HPT. So lets say you make a setout along the way and now your train is only 3400 tons and your still scheduled for 3.5 HPT, you have to do the math and isolate units accordingly to maintain the schedule HPT for FUEL CONSERVATION. Isolate 1 unit in this case and you will be at 3.8 HPT. IF not, you're at 5.1 HPT which will get the crew in trouble if OPTS tested by the roadforeman.
You probably didn't want to know all that but thats how it is done these days.
The "powers that be" decide for us what units, and how many for each train.
Now when business is booming like a few years ago, you get what you get for power.
Oh and for direction...............well thats up to the crew that built the consist. The easiest, quickest possible way to build it. No ryhme or reason other than ease for the crew. Now if you have a 2 engine consist for turnaround service, such as Needles to Ash Hill and back, then obviously you have to have an east and a west facing unit. Other than that, whatever direction the units are facing, thats how they are going.
Number of units is based on HPT (horse power per ton)For example a Z train is usally rated at 3.5-4.0 HPT (again determined by the power desk)so divide the train tonage by availble horsepower.
Dash 9's = 4400 horse power
train tonage for example 5000 tons
So.... 4 units = 17600 horsepower/ 5000 tons = 3.52 HPT
Now if you want to know your speed up Main 1 in the Cajon Pass....
6.23 x 3.52 hpt = 21.9 mph .... so if you're under 22 mph (which is great speed) then 1 of your units is weak
The engineer is responsible for maintaining that scheduled HPT. So lets say you make a setout along the way and now your train is only 3400 tons and your still scheduled for 3.5 HPT, you have to do the math and isolate units accordingly to maintain the schedule HPT for FUEL CONSERVATION. Isolate 1 unit in this case and you will be at 3.8 HPT. IF not, you're at 5.1 HPT which will get the crew in trouble if OPTS tested by the roadforeman.
You probably didn't want to know all that but thats how it is done these days.
The "powers that be" decide for us what units, and how many for each train.
Now when business is booming like a few years ago, you get what you get for power.
Oh and for direction...............well thats up to the crew that built the consist. The easiest, quickest possible way to build it. No ryhme or reason other than ease for the crew. Now if you have a 2 engine consist for turnaround service, such as Needles to Ash Hill and back, then obviously you have to have an east and a west facing unit. Other than that, whatever direction the units are facing, thats how they are going.
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