what is the most number of loaded cars can be in a train before coupler drawbars start breaking?
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It is more about trailing WEIGHT and less about length.
Originally Posted by Hot Water:
It is more about trailing WEIGHT and less about length.
Hot is right. Impossible to say. Sorta like how high is UP?
EdKing
They're right about weight and length (and the amount of tractive force used), plus every train that you watch has numerous couplers and knuckles with hairline cracks caused by the rough service (and sometimes abuse) of railroading. Any of them, depending on future events, may have a long service life or a short one, as the defects themselves almost never cause a draft gear failure. For each, its day will come, when it no longer has the strength to endure one more hard pull. Clean breaks are rare.
Originally Posted by Number 90:
They're right about weight and length (and the amount of tractive force used), plus every train that you watch has numerous couplers and knuckles with hairline cracks caused by the rough service (and sometimes abuse) of railroading. Any of them, depending on future events, may have a long service life or a short one, as the defects themselves almost never cause a draft gear failure. For each, its day will come, when it no longer has the strength to endure one more hard pull. Clean breaks are rare.
Analysts would look at the coupler and analyze how much of the break was new and how much was old. One conductor tried to get past them claiming that a knuckle failure was "100% old break". Yeah. Right.
The design strength of an "E" coupler was, if I remember correctly, 350,000 pounds. I saw a guy open up a knuckle one day with six GP units. I didn't check how much was old break . . .
EdKing
Train length is a local balancing act. It depends on available power, curves, grades, speed limits/restrictions (slow orders), even weather. Yard capacity is anothe factor. In theory, a Multiple Unit Consist could pull a train that stretches to the horizon, but breaking up a train of that length in a yard or running it through a loader/unloader would take too much time.
Unit trains are run point to point. Length is determined by loading/unloading and running time. Fuel costs are climbing so loocomotives have to use fuel efficiently, not roar along in Run 8 (full throttle).
Train length is a lot more complicated than using a MU consist to clean out a yard in one train.
GOOD QUESTION! I look forward to reading more replies.
Come to think of it, a question in a recent thread applies here: Did the B&O run ore trains? ANSWER: Yes, but ore was loaded in coal cars (hoppers), not in ore cars. Ore is heavier (more dense) than coal, so the level of ore in hoppers is well below the tops of the sides. An overhead photo shows that clearly.
EXHIBIT A is a Mt. Carmel ore train between Northumberland and Mt. Carmel. A pair of Pennsy 2-10-0's pulled and another pair pushed to keep from breaking couplers and knuckles with all that weight.
Wyhog, Thanks for those links, they have good concise info.
The use of distributed power is becoming more common so that drawbar loads can be moderated and train handling improved.
