I'm curious - Is the conductor outside for the rule (protection in a reverse move) or just to prepare for the stop to cut off the helper power? Nice capture Sean.
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Third unit from the rear the Engineer seems to be there. So in that aspect, yes the conductor is there for the protection.
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| Posted by Gary on November 20, 2015 | |
9 units on the head end must be close to the capacity rating of the first knuckle!
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An amazing location to catch, and no doubt, listen to trains. Wild!
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| Posted by Dana M. on November 20, 2015 | |
Awesome catch Sean - wonderful description and thank you for waiting to get this photo. I believe the Conductor is preparing for the cut off when they've reached the cut-off point. I will also add my "two-cents" here as well, I suggest that this is another reason for why locomotives should be equipped with ditch lights on both hood ends - for situations just like this one.
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The first knukle of the stacks is being forced with the same strenght no matter if is pulled by 1 or 9 locomotives, the strenght on that knukle is being ruled by the grade and total weight tonage of the train (rolling stock).
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I agree with Dana about the ditch lights. Impressive photo, Sean. It's been a while since I've seen this many locos leading a train. The longest I remember was during my childhood in Northern Utah with 11 locomotives on the lead or head end on a Union Pacific Train. This is too cool. Thanks for posting.
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Nice shot!
Really shows how steep the grade gets just before the crest.
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| Posted by Gary on November 21, 2015 | |
SBC-GP40.
I disagree. For every ton of train weight there is a force of 20 LBS acting on the first coupler to roll back down the hill on a 1% grade. Thus, for a train weight of 15'000 tons there is a force of 300'000 LBS acting upon the first coupler to roll it back down the hill. That is before any locomotives have been added to pull the grade. You will need a force of 300'000 LBS at the first coupler just to hold that train on the grade. On a 1.5% grade that figure goes upto 450'000 LBS! Couplers are rated at 390'000 LBS. Thus IF there were no units on the rear, the train would break in two.
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GARY I totally agree with your comment and that is a totally true fact or example , but how do you know that train weights? i dont think that train could make that mountain with only 2 units as a fact i didnt becouse is being assisted with those helpers, they just wouldnt try to pull it up being assisted with the helpers if the coupler was close to the limit of bracking on of the first car, your first comment was "9 units on the head end must be close to the capacity rating of the first knuckle" how do you know how much train weights to make that comment? and yes couplers are rated to 390,000pounds but railroads will never put that strenght on it , as far as i know they only give them a maximum of 280,000 for safety reazons, Saludos!
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I would estimate the tonnage being around 5,000 tons, but that's a pretty crude estimate. The grade here is 2.2% as well. As far as the force on the coupler, pretty much all railroads have limits on how many units they can put on the point of a train. I assume at least 4 or 5 of the units here were isolated. In a similar situation in the winter a year or two prior, a train had stalled below Motanic with 4 units on the point, and 2 units came down from Kamela to give them assistance, put they had to isolate one of the units.
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I agree with Sean's last comment. They can add as many units as they want but the force on that first coupler remains constant, unless rough train handling becomes a factor. The local RR (CN) have rules restricting their crews on the number of traction motors they can use on a given distance of track, to prevent damage to the rails on heavy pulls.
If a knuckle was to fail it probably would have happened earlier in the trip. Also it is not often the first, but some other knuckle farther back in the train that fails.
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By looking the smoke it seems that locomotives 2,3 and 4 are working in this lashup (from back to front).
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How do the railroads determine how many units they will power a train with? Here in Ohio I watch NS pull intermodal, coal, oil, mixed consists with 3 units like AC-44s or SD70's.
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The number of units we see on a train often has little to do with the power requirements to handle that train. Most railroads use a formula to determine a HP/Ton ratio. This can vary from location to location depending on grades, track conditions, weather etc. The number of units is a different story. Extra units are often added because they are in the wrong location and need to be moved to another terminal. Also some managers who may have extra units waiting for work in their area of responsibility will send them out on a train to make their statistics look better, to increase their chances of getting a bonus on their salary. A train may also have bad order units that are being hauled to a major shop for repairs. The real power supply comes down to how many units are actually working and how many of their traction motors are cut in to supply the necessary power.
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On a certain route there is always going to be a ruling grade no matter if you are going North, South, East or West, the percentage of a grade(A 1% grade means every 100 hundred feet you will climb 1 foot, a 2% means every 100 feet you will climb 2 feet) will tell you how many horsepower per ton you will need in order to climb that ruling grade and also at what speed you will need to climb it becouse DC locos need a certain speed in notch 8 in order to not burn the traction motors (Minimum Continuous Speed), On an AC loco that does not apply . Normally a 1% grade requires 22 LBS per ton, with an AC locomotive lets say an AC4400CW you will get 375 LBS for every horsepower at a speed of 1 MPH so you will do this if you want to climb a 2% grade at a speed no less than 12MPH and know how many tons you can drag per Locomotive and at what speed ,375LBSx4400HP=1650000 than 1650000/12MPH=137,000 LBS of tractive effort so 137,000LBS/44=3125 (44 is the sumatory of 22+22, remember 22LBS is what you will need per ton on a 1% grade) so for every AC4000CW you can drag 3125 TONS at a speed of 12MPH over a grade of 2% so if you have a 6000 TON train you will need 2 AC4000CW or equivalent horsepower units to go over at a speed no less than 12 MPH. Saludos from Mexico!
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