Setting the Reverse Link While Steaming????

I've heard about setting the reverse linkage differently for running under different conditions, but I have never understood why or what it accomplished

For instance, I've heard that for high speed passenger running, you set the throttle wide open and place the reverse link to minimum stroke to save steam .... ? And at other times you would set the reverse link for max stroke and control speed and slip with the throttle ... ?

Then Watash mentioned in another post that while coupling to passenger cars, he closed the reverse link and "coasted on expansion", and that blew my mind

I realize that to understand this, I should have been sitting in the Engineer's seat for lots of years with someone like Watash at my shoulder beating some sense into me

Thanks for any help, Hank

 

Hank'
There is a whole lot of experience that goes into this. The basic simple answers:

With steam up, throttle closed, Johnson Bar (foreward/reverse lever) in centered notch, you are stopped. To go foreward, you shove the J Bar foreward all the way, and slowly just crack the throttle, and the steam under full pressure begins to fill the steam chest, valve chambers, and from there goes into the cylinders. There are ways of getting under way quicker, but that gets into experience. The engine will begin to move and is under full horsepower.You are starting to pull the whole train foreward, but slowly. To gain speed, you increase opening the throttle, and bringing the J Bar back toward the center position.

At full bore (Casey Jonesing it) 80+ miles an hour you have to have a great volumn of steam at pressure.

To prevent wasting steam, water, fuel, and over-working your fireman, you set the throttle at wide open and re-set the J Bar almost back on dead center, to what is called "The Company Notch". This allows a full horsepower to be available, but only enough steam to enter the cylinders to replace the pressure used, to be replaced. Steam expands around 7,000 to 1 so the expending steam also has pressure that will drive the engine too.

You can fill the steam chest with raw steam under pressure, close the throttle off, and just crack the J Bar and move the engine slowly foreward or in reverse quite a ways slowly, like to make a couple. This is "riding the expansion" (of the steam).

Steam is not compressable, so you wont coast at all. The only way you can actually coast, is with the throttle shut, J Bar centered, pet cocks open and no steam pressure in the cylinders, you are just "letting her breathe" and blow air out of the pet cocks as the pistons work back and forth in the cylinders. Your engine brakes are your only control here, risky.

We know that a couple is made at a speed of from a wheel rotating one revolution every two minutes, up to 2 miles an hour. At 4 miles an hour it is a collision! In an ideal situation you only want to couple onto a car and have the latch pins fall into lock position, but not move the car.

If you were backing with the throttle open, and the J Bar full in reverse, when you coupled into the car, the engine would continue taking the car with it. This is sometimes done in switching cars in the yards, but is hard on equipment.

That is very basically what happens. There is of course more to it than this. You can also toot the whistle!

 

Thanks Watash,
That's a great explanation of the basics, I wish magazine writers would explain things that clearly.

Based on what you said - when you have a heavy slow drag on an upgrade and need full power, I assume you would open the throttle wide and work the J-Bar to prevent slipping?

Thanks again, Hank

By the way, I WAS allowed to sit in the right seat of a B&M Consolidation and blow the whistle back in the late 40's

 

Yes Hank, if you are "chasing the grade" and say you have 18,000 tons trying to pull you back down, then you probably are doing both. You may have to sand the rails, hold the throttle "feeling" for slip, and have the J Bar up into the high notches. If the drivers do get away from you, they can spin so fast the friction can heat them hot enough to expand off the spokes, and you are on the ground tearing up Jake! If you are handling an articulated, you have tremendous horsepower and double trouble too. The front engine (set of drivers) have a little less weight on them, so are more likely to slip than the rear engine. This is more a problem when starting out from a stop, than while going up grade. I have seen Big Boys spin the front engine many times when starting a train a couple of miles long. That's impressive! Back about 1941 I was told the company lost $128.00 every time a driver slipped one revolution! It also "spalled" the rail head, and wore a groove in the driver tire. What is more scary is to top a hill and start down and find your drivers are turning at maybe 20 miles an hour yet your train is going 30 miles an hour! Your train has started a runnaway and you didn't set train brakes soon enough! The best thing to do in this situation, is to bend over, grab your ankles and kiss your butt good bye!

 

Watash, your explanations are great! Especially liked the last one. If you were rolling varnish with full throttle, what would happen if you had the J bar near full forward instead of the company notch?

 

Watash, I imagine that having 18,000 Tons pushing you down a hill can pull your pucker string up real tight

From your explanations, especially with running an articulated, you must be very good at rubbing your belly, patting your head, and dancing an Irish Jig, all while being stone-cold sober You make it sound like today's diesel drivers have it really soft

Thanks again for everything, Hank

 

I have heard Engineers complain about condensation causing wheel-slip,(from the steam exhaust?), and mention running an engine "skin -tight", especially the latter,could someone elaborate? Thanx, Bobby

 

Fitz, I don't know. I don't think anyone has ever lived to tell about it.

 

I read a story in Trains a few years back written by a retired Pennsy Engineer. He said he had to make up time and ran a T-1 at better than 100 mph for over an hour through parts of Indiana and Ohio. I assume he was very close to full throttle and full J Bar!

I've heard that the T's were some of the smoothest running locomotives ever. This could be why he was able to run that fast for that long. (of course, he may have burned up the auto-stoker and also his fireman )

Hank

 

A technical point. Steam expands to 1600 times the volume of liquid water, by far the greatest expansion of any substance changing from a liguid to gaseous state - which is what made it so useful to create power. The purpose of superheating steam was to keep it from recondensing into water. The superheater, which was entirely inside the locomotive, was one of the greatest advsnces in steam locomotive efficiency in the 20th century.

 

Gregg is correct and made me realize I meant to put about 1700 to 1 but I had posted 7000 to 1! HA! old age! Thanks Gregg.

Bos,
The condensation they were complaining about, is when an engine has been sitting, the steam will condense into hot water inside the cylinders. If you have say a couple of gallons of water in a cylinder, and you set the Johnson bar to go and start to open the throttle, the piston will shove the steam out easy, then try to compress all that water just as the valve is closing and you suddenly have a hydraulic lock because that water has nowhere to get out. So it stops the engine's wheels, or it blows the end out of the cylinder! That is why, before you ever think about moving a steamer that has set a while, you must open the cylinder cocks (pet cocks down on the bottom at each end of both cylinders) so any accumulated condensed water has a place to get out. Some amount of water will be blown up into the steam chest, but will run back down to the cylinders. You may have seen movies of great white plumes of "steam" blowing far out each side of a steamer just as it is starting up? That is what the engineer is doing, he is clearing all four chambers of his cylinders of water.

Say you slowly back into your string, and get coupled up. Your throttle gets closed, the J Bar is centered, engine brakes are set. The brakeman stiches her up (connects brake hoses between the string of cars and the engine), then signals for the engineer to make his brake check. Maybe he has to pump up the whole string, which is a lot of volumn, so could take maybe fifteen or twenty minutes more. All the while this is going on, water is condensing in the cylinders, and the last charge of dry steam is still in the cylinders with the valves shut. The full horsepower of that engine is just sitting there trapped, waiting for a valve to open even a little bit to let that dry high pressure steam excape along with the steam that is now expanding in the cylinders.

All you have to do, is forget to open the cylinder cocks!! Because if you do, when you first begin to move the J Bar, that is shifting the valves and all that pressure will suddenly try to get out at the same time the full boiler pressure of dry steam will try to go into the cylinders, and your wheels are going to go crazy! Your engine has either kicked the cars behind, or tried to drag them off down the track.

If you have bunched your string, and you get too much speed while the slack is being taken out of each pair of couplers, when it gets to the caboose, you can kill your conductor! He will have been sitting still and in less than a second his caboose is going 10 or fifteen miles an hour while his body is remaining still, until the rear caboose wall hits him! That was also another reason the caboose was abandoned. Everyone on that train was a team, and most times were friends.

As a matter of fact, a Class 1 railroad was sued by an employee who's friend had been splattered over the end of a car, and the railroad ordered him to go clean up the mess after his friend's body parts had been bagged. He of course couldn't bring himself to do that. The railroad told him that he will clean it up, or be fired. He cleaned it up, then sued the railroad.

You hate to lose a friend, and everyone knows it is dangerous. You expect someone to clean up the cars, but it usually is not a team mate or relative. That is asking too much! I hope he got a sympathetic Judge!

It is the same with a diesel, except the steamer will store energy. Both can hurt you or someone else, that is why the attention given to safety, see?

People got to learn, that if they try to beat a train, or get careless around one, they can be bug splat too! Would they want their mom to come wash them off the front of an engine?

[ 02 April 2001: Message edited by: watash ]