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NPR radio each week has Car Talk which has a puzzle for listeners to solve and send in answers.  Last week May 10th this was the (railroad related) puzzler:

 

RAY: Imagine, if you will, a long freight train. It's pulled into the train yard and all the workers get out to go to the bathroom. They get back in and the engineer opens the throttle and the train starts to pull away from the yard, when they realize the caboose has a problem. The brake is frozen on one of the wheels of the caboose. The wheel is being dragged and there's sparks and smoke.
TOM: Yeah.
RAY: And someone standing there says, "Stop the train." So, they manage to signal to the engineer to stop the train. They can't fix it, so they just cut the caboose loose. They remove it and they give him the go ahead. He gives it the throttle. The train doesn't move. He gives it more throttle. It doesn't move.

What's happening is the train isn't moving, but his wheels are spinning. The cars aren't moving. There's nothing wrong with any of the remaining cars and there's nothing wrong with the engine, but there is something wrong with the engineer.
TOM: Wow. This is good.
RAY: The question is, what's wrong?

*****************

This week May 17th, answer was:

RAY: When a locomotive is pulling cars, each car is attached to the one in front of it and behind it by a coupling, but the couplings aren't rigid. They are, in fact, sloppy. When a long freight train pulls into a yard, before it takes off, it will frequently back up to compress all the couplings and then when it takes off, one car at a time begins to move and it's quite a while, in fact, before the caboose begins to move.

But in this situation, the train was stopped. He did that backing up thing. I failed to mention that in the statement of the puzzler.
TOM: Another form of obfuscation, and nicely done, I thought.
RAY: The train is halted because the brake is stuck and because it's stuck, the caboose is in a sense pulling the train from the other end. So, now all the couplings are all stretched out. They remove the caboose, but the guy doesn't back up.
TOM: Right.
RAY: They give him the go ahead. He says, "OK. I'll go ahead."
TOM: So, now he's going to pull all 750 cars --
RAY: At once. He's going to try to move the last car while he's trying to move the first car and the train is just too heavy. He doesn't have enough friction between the wheels and the track to accomplish this.
TOM: So, a train can't really pull from a dead stop all the cars that you see behind it sometimes.

*************

When they said they cut the caboose loose I figured someone forgot to close the angle cock so all brakes were still on (fail safe).  Their answer makes no sense, as I thought only steamers did the backup to gain slack, not modern diesels with computerized wheel slip etc.  Now this has me puzzled.

 

But of course I am only an armchair railroader.  Feel free to chime in.

Last edited by rrman
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So many things wrong...so little time. 

 

750 cars? No way. The longest train ever run was somewhere around 500 cars, if I recall. And the railroad involved (C&O? N&W? I can't remember.) quickly decided it was not worth the effort. A 750 car monster would be all but impossible to move over the railroad and it would require multiple sets of distributed power.

 

If all the slack was stretched, how did they uncouple the caboose? If the brakes were stuck on the caboose, they would have HAD to take slack to uncouple it!

 

Diesels will occasionally have to take slack to start a train. It depends on a lot of variables. Train weight, grade profile, stopped going uphill or down...lots of variables.

Originally Posted by OGR Webmaster:

So many things wrong...so little time. 

 

750 cars? No way. The longest train ever run was somewhere around 500 cars, if I recall. And the railroad involved (C&O? N&W? I can't remember.) quickly decided it was not worth the effort. A 750 car monster would be all but impossible to move over the railroad and it would require multiple sets of distributed power.

 

If all the slack was stretched, how did they uncouple the caboose? If the brakes were stuck on the caboose, they would have HAD to take slack to uncouple it!

 

Diesels will occasionally have to take slack to start a train. It depends on a lot of variables. Train weight, grade profile, stopped going uphill or down...lots of variables.

It was the N&W which ran the 500 car monster coal train.  It had nine SD45s to haul it, three on the front, three mid-train, and three pushing the rear.  It also had several break-in-twos along the way.  It was never meant to be a regular operation, just a "let's see if it can be done" test.

 

Stuart

 

I love the car guys and their puzzlers - I listen for it each week.  It's never bothered me that puzzles often have slightly unrealistic numbers: many of these problems are really cool despite that, this one included.  I got this one almost immediately - I recall my uncle talking about how important this was when starting a long train.  When they broadcast it, I thought of sending in the answer - but I won the weekly contest years and years ago and my wife insists anyone who has won once should let others try, and not enter again. 

Originally Posted by RickO:
Originally Posted by Hot Water:

750 cars????  How did those idiots come up with THAT?

Their "car talk" guys, not "train talk". Having said that, their "car talk" can be questionable as well.

Really? Car talk answers are questionable?  RickO, you just shattered my full trust and faith in Car talk guys answers.

Actually every Saturday, I'll say to wife, "well time to listen to the village idiots again"   The way they laugh so much, makes me wonder if they let these loonies out once a week then lock them up again for safety.

Still good for morning listen while having coffee......

 The N&W train in question in one of the reply's, had six SD-45's,500 loaded coal hoppers and a caboose.Three units on the headend,three in the middle.

 It ran from Williamson,WV to Portsmouth,Ohio.

 I have worked with three of the five crew members in my career.Sadly all five crew members have passed on now.

 I was told the train started out pretty easy and ran down the road fine.But when they brought it to a stop in Portsmouth they busted five knuckles,and had Portsmouth tied up for hours !

 I think Australia holds the world record for tonnage and amount of cars now.

 

 I have started trains out of Kenova going up the East Leg by setting a little air shoving the slack then starting out with them just like Wyhog mentioned.

 

 Now on the flat and mostly level like leaving Williamson,I've had no problem in the past starting out with 272 loaded coal cars and three SD-40's.Actually done that once with three four axles there in Williamson.Didn't make it too far because the lead engine burnt some modules out. 

 With these newer engines I've had 200+ and only two motors and ran fine.

Last edited by mackb4

To add to what mackb4 offered, back in 1962, when I was working with the new N&W GP30 units out of Portsmouth, Ohio, The N&W was regularly operating 275 to 300 empty hoppers out of Portsmouth back to Williamson with just 3 GP9s. Two new GP30s would handle 230 to 240 loads from Williamson to Portsmouth (normally 23,000 to 23,500 tons). 

 

While I wes there, the Trainmaster tried a 300 car empty train out of Portsmouth, and surprisingly it had no trouble at all getting back to Williamson. The next week, a 350 car empty was tried. That didn't work out very well, what with broken knuckles and such. They returned to running the "normal" 275 empties back to Williamson.

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