Locomotives in front vs. back of a consist.
- Thread starter Xengeance
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jadebullet
might be back?
Yes, when you are pushing a string of cars into a stub ended piece of track with no runaround.
cascaderailroad
New member
As a test, I once pushed a 100 car train uphill, at 45 mph, using 6 pusher locomotives on the rear end, on a 2.5% grade on my Horseshoe Curve route, with no locomotives on the head end...and it didn't derail.
The helpers automaticly follow the same speed as the lead driving locomotive. And helpers on a rear end can not over shove, and bunch up a train off the track, like it would in the real world of trainhandling.
So it seems to make no difference, unless drerailment realism & realistic drawbar physics rules are enabled.
The helpers automaticly follow the same speed as the lead driving locomotive. And helpers on a rear end can not over shove, and bunch up a train off the track, like it would in the real world of trainhandling.
So it seems to make no difference, unless drerailment realism & realistic drawbar physics rules are enabled.
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Michael_Evans
thread killer
This practice is beneficial on local freight trains. The locals in my area use a locomotive on the front and rear so they don't have to runaround at every siding. It is also beneficial when a train is a point to point and there is no wye or runaround.
magickmaker
New member
In flat terrain, it's better to keep the power at the front, since the slack motion (play between the cars) isn't going to be that much of an issue. This is double for short trains, since spread out over the length of the train it never builds up much.
The problems begin when one of three factors are added in. They are length, grade, and weight distribution.
With length, you start reaching a critical mass around 100 to 150 cars. Anything over that (save for a car or two) and you start placing a great strain on the lead cars couplers. In these cases, many railroads will try to ease off the pressure by placing a mid train helper. Really, when you get down to it, this locomotive is just there to take the weight off the lead ones, keeping the pressures on the cars to a minimum.
With grade, it becomes a problem of pulling power. In these cases, Railroads will typically spread the power out, placing a locomotive or two or three on the front, possibly one in the middle, and one or two helpers on the rear. In many cases, the rear end helper actually is not "coupled" to the train, but rather will "cut off" of it on the fly when the other train reaches the summit that it was seeking. This is a current BNSF practice, using a rather curious computer based system. In steam days, some railroads (NW for example) placed outdated but powerful locomotives at long grades and designated them "helpers." These helpers had no front coupler, but instead had a heavy iron plate which was used to push the other train up the hill. The NW turbine engine Jawn Henry, lived out its days in this manner.
Lastly is weight distribution. With weight distribution, the problem becomes one of control. The locomotive on the rear may not be there so much as to provide power to push the train up the hills, as to provide added braking power. Acting much like a british "Brake" van or a caboose from days past, the locomotive uses its weight and brakes to keep the tension and slack of the train down enough so whatever weight in the train doesn't cause it to derail or telescope into the rest of the train. You'll rarely see this done, due to modern braking, but in the past this was a common practice on many railroads. PRR was one of those that comes to mind.
The problems begin when one of three factors are added in. They are length, grade, and weight distribution.
With length, you start reaching a critical mass around 100 to 150 cars. Anything over that (save for a car or two) and you start placing a great strain on the lead cars couplers. In these cases, many railroads will try to ease off the pressure by placing a mid train helper. Really, when you get down to it, this locomotive is just there to take the weight off the lead ones, keeping the pressures on the cars to a minimum.
With grade, it becomes a problem of pulling power. In these cases, Railroads will typically spread the power out, placing a locomotive or two or three on the front, possibly one in the middle, and one or two helpers on the rear. In many cases, the rear end helper actually is not "coupled" to the train, but rather will "cut off" of it on the fly when the other train reaches the summit that it was seeking. This is a current BNSF practice, using a rather curious computer based system. In steam days, some railroads (NW for example) placed outdated but powerful locomotives at long grades and designated them "helpers." These helpers had no front coupler, but instead had a heavy iron plate which was used to push the other train up the hill. The NW turbine engine Jawn Henry, lived out its days in this manner.
Lastly is weight distribution. With weight distribution, the problem becomes one of control. The locomotive on the rear may not be there so much as to provide power to push the train up the hills, as to provide added braking power. Acting much like a british "Brake" van or a caboose from days past, the locomotive uses its weight and brakes to keep the tension and slack of the train down enough so whatever weight in the train doesn't cause it to derail or telescope into the rest of the train. You'll rarely see this done, due to modern braking, but in the past this was a common practice on many railroads. PRR was one of those that comes to mind.
Thanks for all the info guys, it may come in handy some day 
. Although with what Magicmaker was talking about with using locomotives at both end on steep grades, in times before the advent of computers, how were they able to syncronize each engine's speed/braking, as I would assume too much or too little power on one side would snap the train in half like an overstretched rubber band?
. Although with what Magicmaker was talking about with using locomotives at both end on steep grades, in times before the advent of computers, how were they able to syncronize each engine's speed/braking, as I would assume too much or too little power on one side would snap the train in half like an overstretched rubber band?In the UK, the London(Waterloo) to Weymouth line used this push-pull method (as it is known here). A powerful 4-coach EMU pushed 1 or 2 4-coach trailer units to Bournemouth where a diesel locomotive hauled the coaches to Weymouth and then pushed them back. The EMU then pulled them back to London. Before this, the allowed limit was two coaches, so was confined to slow speed branch lines. It was only approved after tests up to 100mph. It was superceeded when the Bournemouth-Weymouth line was electrified and normal EMUs were used.
Thanks for all the info guys, it may come in handy some day
They used whistle codes
British Rail introduced High Speed Train (HST) sets in the mid 70s which consisted of 2 lightweight power cars at either end of a rake of 7 or 8 coaches. The locos were built solely for high speed passenger use and are still in use today which is a feat in itself given that they were desinged as a stop gap measure and BR wasn't best known for reliable traction.
These HST sets have an in-service speed of 125mph (can actually reach speeds of 144mph).
Push/pulls were commonly used prior to the introduction of the HSTs. These consisted of a loco at one end and a driving brake (DBSO) at the other, converted from a standard coach. This meant that there was a driver's cab at either end and the train could run point to point. A modern high speed version of this method is still in use in the UK (class 91 and mk4 DVT) and also in Ireland.
These HST sets have an in-service speed of 125mph (can actually reach speeds of 144mph).
Push/pulls were commonly used prior to the introduction of the HSTs. These consisted of a loco at one end and a driving brake (DBSO) at the other, converted from a standard coach. This meant that there was a driver's cab at either end and the train could run point to point. A modern high speed version of this method is still in use in the UK (class 91 and mk4 DVT) and also in Ireland.
The main benefit of having power at different points of the consist is the limits of the coupler drawbar force. You can learn a lot from this site:
http://www.alkrug.vcn.com/rrfacts/rrfacts.htm
ARR Coupler
Drawbar pull tractive effort rated with a minimum strength 350,000 pounds (160 t) for general service coupler made of Grade B steel. Grade E knuckles may have an ultimate strength of 650,000 pounds (290 t).
http://www.alkrug.vcn.com/rrfacts/rrfacts.htm
ARR Coupler
Drawbar pull tractive effort rated with a minimum strength 350,000 pounds (160 t) for general service coupler made of Grade B steel. Grade E knuckles may have an ultimate strength of 650,000 pounds (290 t).
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An example of what Michael says was Conrail operations on the NEC. Amtrak owned the rails so whenever they said, "clear the track," Conrail had to. Having an engine at each end when serving local customers made it faster to provide service while keeping Amtrak happy by giving them clear rails.
jammydodger
New member
Let's spend a few million pounds on an outrageous tilting train!
*later.....*
NOOOOOOOOOOOO! Ha well, we'll just have to scrounge some more money, eh? Harrison! Raise all the prices on the East and West Coast services by 25%, and all commuter services everywhere by 30%! All dining car costs go up 15%! Snack trolley up by 10%! Buffet car by 15%! Make everyone pay a penny before they can use an on-train loo!
Ah, now to sit back and watch my company fall apart whilst trying to make money..... Tea! Get me some tea and a packet of Bourbons!
That'll be £7.29, Sir!
NOOOOOOOO! I DON'T HAVE ANY CHANGE!!!!!!!!
yeah, actually it does help. uprr runs many trains distributed power. what that basically is is the helper on the rear or midtrain is controlled by the engineer on the headend. i see KCS uses them too as well as bnsf. don't know that much about it seeing as im on flat ground but apparently it helps in mountains or hills.
True & after all that is the way the European high speed commuter rail has been run since it's inception but other than shunting work in a siding or railyard you don't generally see that many loco's pushing a consist in these parts.
They run these all the time from Ft. Worth west. I live about 3 blocks from the tracks here and I see them every day.
In my part of the world, I see quite a number of unit coal trains on both BNSF and UP. Both railroads typically operate the 110 car trains with two units at the head end, and a single unit on the back end of a loaded train. Empty, it is not uncommon to see the trains running "backwards", with a single unit at the front, followed by the empties, and two units at the rear.
ns
on the hill (donner summit, 2.6% ruling grade) where i grew up, the sp used mid train helpers as standard practice on long freight trains all the time. head end kept control of the air. in steam days, with the cab forwards, which were the standard power on the hill then, they used TWO mid train helpers in two different postions. one 40 cars back from the head end and the second 20 cars ahead of the caboose. (yes trains were typically that long in 40ft car days, 80 cars considered a 'short/light' train, and 125 or so not at all unusual)
cascaderailroad
New member
On the Blue Ridge Subdivision (The old Clinchfield) they now usually have 2 ES44AHs in front and 1 in the back, I can hardly see anything else along that line nowadays!
That's what is great about Trainz...do alot of research on a particlar line, that is now almost defunct...and recreate it wayback in it's hayday of yesteryear.
My favorite era, and speciality of study is, from the Canal Period (1790-1815) up through the Diesel Transition era (1956).