As a new model railroader, please answer some questions for me. What does the term “varnish” refer to? What does it mean to “pull a drawbar”? Thanks much.
Back when passenger cars were made of wood, heavy coats of varnish were applied to the premiere cars to make them gleam and shine. Some old photos almost make them look like metal. Compare to boxcars and other wood cars that might have had a bit of shine when new but would get chalky and dull with time. The railroaders would refer to those premiere trains as “the varnish.”
I suspect but don’t know for sure, that the varnish was reapplied often to keep the cars looking nice. References to “the varnish” might in part have been to the smell!
The drawbar is what the coupler is attached to. It can swing from side to side a bit and there is slack in and out as well (less so for passenger cars); modern ones have cushioned springing action built in. If the train was heavy on starting up the weakest link was often the drawbar’s attachment to the car, so sometimes the whole thing would be yanked free – pulling a drawbar. It still happens from time to time. In the early days of PRR electrification, the immediate horsepower being applied from the electric locomotive was higher than with steam, and over time cars and drawbars needed to be beefed up as a result. Pennsy ended up converting some of their early electrics to pushers because they just kept pulling out drawbars.
Dave Nelson
The drawbar, as described is the portion of the coupler that fits into the car end.
It can break, either from wear and fatigue or from being rapidly or overly stressed. the engineer accelerates to rapidly or is going up a grade and there is too much weight on the drawbar (over 8000 tons) it can case it to fail. If an air hose bursts or the train goes into emergency the slack forces in the train can cause a weak drawbar to fail. Normally the knuckles fail before the drawbars.
The housing or center sill can fail and rip completely out of the car (known as “gutting” a car).
There is either a horizontal piece of metal (crosskey) or a vertical metal pin that keeps the drawbar in the center sill. If the parts that keep the crosskey or pin in place break and the crosskey or pin falls out, the drawbar will come out.
The danger of a drawbar coming out is that is a very large piece of metal and if the train runs over it, it can derail the train, or the coupler can drop and wedge in the ties and “pole vault” the end of the car up in the air, derailing the train.
A crew cannot repair a drawbar failure, that takes heavy equipment and welders (as opposed to a knuckle which the crew normally can replace).
If the drawbar fails in the leading end of a car, it is known as a “wrong end” drawbar because the train cannot couple back into the car to move it to a siding to set it out. The crew has to chain or cable the the damaged car to the train and move it to the siding, or a following train has to couple into the rear and set the car out from the rear. On the other hand a crusty old General Manager once pointedly told me there was no "right’ end to get a drawbar.
Just a “small” addition…
If a knuckle breaks or a drawbar breaks/pulls out…
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it won’t usually show up if the back part of the train is bunched up and “pushing” against the front part of the train… as when going down grade or slowing/stopping.
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when the train transitions from downgrade to level or up grade and/or from slowing to accelerating Or when the train is all being pulled… then the break will show up.
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It will show up by ceasing to do its job of keeping the train coupled together.
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As the train divides and space increases between the cars the coupled hoses for the automatic brake (in modern times an automatice air brake) will first stretch out… when they reach their length limit they will either be ripped apart or ripped from the end of the car with the weakest attachment. (This might not be the car with the bust coupling).
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As soon as the brake pipe breaks all the air in the automatic system will be dumped causing a full application of the breaks in all cars in the train. (An auto brake normally holds the brakes off to allow the car(s) / train to move… it automatically goes on if the air pressure falls too low… as when it all escapes through a broken pipe).
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The whole train should come to a shuddering halt.
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I say “should” because brakes, like engineers, do not stop trains.
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Only two things stop trains… (1) friction between the brakes and the wheels (or discs) combined with friction between the wheels and the rails. (2) anything larger and more solid than the train…
They won’t “rip apart”, they merely disconnect. The air hose connections are designed to automatically disconnect when pulled apart. Happens every time a car is switched from an inbound train.
Not in the US. Released train brakes will have no pressure in the brake cylinders. they apply when pressure is introduced into the brake cylinder and release when pressure is rreleased from the brake cylinder. The normal position of the brakes is released. The brakes are activated by the difference in pressure between the air reservoir on the car and the train line. Teh pressure in the line doesn’t “hold the brakes off”. Only direct air and vacuum systems did that but they haven’t been used in the US since the late 1800’s.
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The difference between all the brakes going on and the train coming to a stand (which also depends on the weight and speed of the train and whether it is going uphill or down) is what allows lumps that have fallen off a car’s drawgear to get under the wheels and derail the train or otherwise tip it off…
however, if the derailment occurs before the train has stretched out and any part of the train “lands in the dirt” (i.e. hits the planet) the detached part of the train will usually be slowed down enough to stretch out the break in the train and snap the air pipes… dumping the
Here is a gutted boxcar.
http://www.railpictures.net/viewphoto.php?id=244396&nseq=774
Kadee #500000000000000000008 conversion.
Wasn’t meant to be a tutorial. Was based on working experience (if limited in some respects). Sorry to offend you.
The one time I was close to a buckeye coupler failing the two parts of the train seperated very slowly (almost cartoon style) and the glad hands failed to part (sorry I thought that going into glad hands would be a bit too much)… the result was eventually an impressive bang as the metal pipe on one car snapped.
I did raise a query about whether a US train would be allowed to move at all with some defective brakes… But I’m left wondering how a defective car is set out without moving it if a train divides miles from the nearest spur or siding?
I would guess that ripped out drawgear was much more common in the early days when there were a variety of automatic brakes and (to soe extent) less rigid working methods. Isn’t this one of the many things that has lots of “era specific” elements?
Apologies for offense
[8D]
This means that if a train divides, can be hooked back together and the air brake can’t be made right through from front to back… it can still be moved… but the back part of the train will not be braked… This was less of an issue when trains had a caboose at the back. It may not be allowed at all now???
No offense. A bullet list seemed tutorial. If you were describing UK practices that wasn’t evident. I know a lot of things mechanical are different in the UK than in the US.
The pipe was probably defective. The first time a car is switched in a yard the air hoses part automatically . A major US class one might switch 100,000 cars a day so the air hoses have to separate that many times automatically. Add in every time a train makes a cut to set out or pick up, the air hoses part automatically. So its something that happens all the time. Damaging the cars is very, very rare.
100% of brakes have to be working out of origin. 85% of the brakes have to be working at any given point.
If the air brakes are inoperative you ca
[:O] WOW! Thanks for that explanation! Lots of stuff that’s very much the same but slightly different in there.
I think it’s probably best if I leave it at that unless anyone wants us to go into more details… then I can be vague or get things wrong and you can correct me! [;)] It’s a long time since I worked directly with brakes. Most of the time I just try to explain to completely non-rail people that if there is a problem on a train the brakes automatically come on in a “fail safe” manner… so long as the train has been put together correctly.
The risk of brakes leaking off is why we have schedules for how many cars in a cut left standing must have the brakes wound on by hand… naturally problems then arise when people don’t unwind those brakes before moving the cut, this (as Dave will know) is how cars get flat spots on the wheels.
At the car works near me they don’t just wind the brakes on but put wood wheelstops under the wheels at each end of any cut… some of the cars are probably there with brake defects anyway.
That gutted car http://www.railpictures.net/viewphoto.php?id=244396&nseq=774 is weird… How on earth did the centre sill get ripped out with no sign of damage to the sides? I can guess that it’s the sliding element of a cushion frame but it still seems weird to me. I’d guess that the cars brake pipes got bust somewhere underneath the car!
[8D]
The train line is attached to the sliding center sill. At some point there is a “branch pipe tee” where the line from the train line branches off to the brake valve (the branch pipe). On this type car that is a flexible hose. When the retainers that limit the travel of the sliding centersill fail, the center sill slides out and the flexible hose branch pipe is severed. So the train line isn’t damaged, but the branch pipe is. Well sorta. The trainline on the other end may be damaged where it was drug through the underframe.
Hopefully if your unlucky enough to have the trainling go bad on you, you have a run a round hose on your power. So that way you can cut the car out and just bypass that car’s section of the trainline with your run a round and continue on your way. Another nifty lil part is a trainline repair clamp I have one in my grip that will temp fix up to a 2" hole. Either way then just tag the car and put it on the airslip as cut out and when it gets to the next terminal you can set it out.
Dave the train asked: did raise a query about whether a US train would be allowed to move at all with some defective brakes… But I’m left wondering how a defective car is set out without moving it if a train divides miles from the nearest spur or siding?
In that case a car man would be called to fix the problems if we couldn’t.98% of the time we fixed the problem since most brake problems was a busted air hose.
Now looking at a busted draw bar-that seldom happen 99% of the time the coupler face would break before the draw bar since there is much more force on the coupler.
The risk of brakes leaking off is why we have schedules for how many cars in a cut left standing must have the brakes wound on by hand… naturally problems then arise when people don’t unwind those brakes before moving the cut, this (as Dave will know) is how cars get flat spots on the wheels.
Not always…Some times the brakes won’t release and the car is dragged…This is why the rear brakeman made a roll by inspection as the train departed the yard.Once on the main any crew waiting in a passing siding will make a roll by inspection and either radio you or give you a hand signal indicating you have sticking brakes.
Some roads may have used different hand signals, but one common hand signal for sticking brakes was to hold the hands together horozontally palm to palm and slide them together and then point to your body to indicate the location of the car in the train. Point to your head for the front, to your waist for the middle, to your knees for the rear of the train. Of course, at night it would be hard to see all this, so sometimes a stop signal would have to be given with a lantern.
Thank you. I was about to issue a similar correction. Saved me time and trouble.