Johnson bar

I did a search and found both meanings. One, which supports the 'hard working" concept, is this:

Wall Street Notch Forward corner of reverse lever quadrant in engine cab (more commonly called company notch). Called Wall Street notch because engine pays dividends when heaviness of train requires engine to be worked that way.

There were other references which supported the "most efficient" definition. I guess this is one of those terms which had more than one meaning, depending on where you were working.

Most efficient--definitely, but with due regard to the full load hanging behind the tender. If you were pulling a full load with a steam loco on a steep grade, you'd go no faster in full gear than in the company notch. These machines work on expansion, a little steam can take you a long way.

Mick

Hi everybody,

Let's just note, that a steam engine can't pull heavy tonage up a steep grade, without the reverse lever being put further foward, or backward, to allow more steam to go to the pistons without slipping the wheels, to a certain extent. With the reverser all the way foward, or all the way back you use up steam inefficiently, there for using more coal and water. So it is recomended to run with the lever as close to the center as you can when on flat ground. However, to get a train started, the reverse lever must be all the way foward, or all the way back, and then pull the lever back closer to the center, as you gather speed. (Note that the reverse lever is aka the Johnson Bar, sorry for any confussion, but somebody at Steamtown told me that Johnson Bar is not the correct terminology for it, so I call it the reverse lever.)

Joe

While not the 'technical' term, 'johnson bar' can not be labelled the incorrect term either. In railroading, COMMUNICATION is the thing that makes safety work, so as long as the intent behind the communication is carried, no one cares much how it is carried... ie: the official technical term for NORAC rule 135 is 'Stop Signs'. however, nearly everyone uses teh incorrect, unapproved 'Stop board'. This seperates the signal in question apart from the red octogon alongside a paved road, and at teh same time, eveyone understands we are reffering to teh working limits setup by MoW for their people's protection.

A similar example: even today, its still called a 'whistle post' and is a white board with a bold black "W" on it. When was teh last time you heard of a 5-chime Nathan whistle? Or heard an N&W hooter on an NS DASH-9? But, it still conveys the intention despite the fact that the original technology has long ago faded into oblivion.

Back to the mechanism... although almost exclusively used together in the USA, the locomotive should function superiorly with a wide open throttle (closed only in coasting or stopping) and power controlled via teh reversing mechanism. The reason is that the throttle being partially open will cause a reduction in the steam pressure before the steam even reaches the cylinders, there-by reducing the available power. By using the reverser, the steam is controlled via the cutoff of the valves, and hense full pressure is given to the cylinders for as long as teh valve is open. This is more fully explained in David Wardale's book 'Red Devil'.

Many years ago i asked the same question. The answer i was given is that in the early days of steam, before
power reverse was invented or mandated, the term was "jouncin" as in bouncing around. This was because
as steam engines grew in size the associated parts of the valve linkage grew also. You can well imagine
in a typical large 2-8-0 of the early 1900"s the mass of metal that was moving around when the engine was
underway. When an engineer changed the reverse lever position to "notch" up or down he had to hang on
for dear life! Hence the term orignaly was "jouncin bar" which over the years morfed into Johnson bar.
Many enginers back then prior to power reverse suffered serious back injury from working on the large
brute steamers with no power reverse.
just my two cents

That very neatly explains the evolution of the name johnson bar.

Wonder if there is any way to confirm such a theory?

jgallaway81

While i certainly cant document my answer to the orignal post, i can tell you this from first hand experience.
When running a steam locomotive that does NOT have power reverse, when you change the position of the
reverse lever/bar on the quardarnt, you will most definately feel the movement ie: " back and forth "of the
associated linkage to the valve's. Think of it as a tug of war between a couple of mules, every rev of the
engine. With small narrow guage or industrial locomotives this is not too much a problem, given the smaller
size overall and the slow speeds. When you get into large standard guage steam locomotives its a whole
different story! I wood venture to say that on the large pre-power reverse engines the associated linkage
in the valve train could weigh a half ton or more, so you can well imagine the inertia that was sent back to
the "johnson bar" and then to the poor bastard running the engine!! If by bad chance the engine would
slip at the same time the enginer was changing the quardarant setting of the reverser ie: dropping down
a notch or two. he might well be thrown into the cab wall...

Hope this will help.... trapper

Trapper has well spoken.
We in Germany have two different types of reversers.
The one with a lever, like in the old 0-4-0 locomotive "Landwuerden":

You can see the lever on the right side of the boiler back end... the throttle a ring shaped handle on the top of the boiler, difficult to see in the picture.

All other engines got screw driven reversers. We call such srews also spindles, because need to turn for operation

Watch the right side of the cab and note the large wheel, this is the handwheel to move the reverser. In Germany we had no browns engines or air cylinders for moving the linkage. So there is no Johnson bar anymore.

The Johnson bar is a lever with a ratchet mechanism, to keep the lever in dinstinct position on a given quadrant. On our screw linkage drivers there is no ratched anymore. You can see in the middle of the reverser wheel a disc with holes in it. A small locking mechanism uses these holes to keep the reverser wheel in the given position.

Trapper told about the effects one can feel on the reverser if the engine is moving under steam. Now we have to think about this:
A steam locomotive with a Johnson bar is shunting a huge freight train. Small locos might not have the look, but some of them could move 2000 metric tons - not fast, but slow and continuos. Let's consider a small shunting engine pulling a freight train on shunting backwards... After pulling, the train gets in motion and because of good rolling of the train the driver does not shut the throttle to adjust the engine, he want's to uphold the pulling force, but reduce the amount of steam taken by full stroke admission. So what to do? Trapper mentioned before: You have to adjust the cut off, and as more you get close to the center, as better.
So our engineer grips the Johnson bar, unlocks the ratched and...
Well, Trapper said, there is huge power acting on the valves, thus moving the whole linkage, and thus our Johnson bar, attached to the linkage will also be a part of it. But there is another factor, which admits the momentum to the Johnson bar: The weight of the linkage. Usually on a walschaerts gear the whole valve rod, pulls the linkage to the Johnson bar downwards by gravity and weight. On certain other gears, like the Stephenson gear the weight increases because having the radius, and two excentric rods hanging on the linkage or reach rod...
back to our unexperienced engineer who want's to adjust the Johnson bar, we remeber, he is going backwards full stroke and wants to adjust the linkage more to center to drive more economic.
By the load of gravity and the power of steam to the piston valves that handle is teared off his hands and within an eyes blink and much faster than the old rusty ratched could prevent, the lever swings over from back to full ahead... We remember? Steam engines ca be switched from full ahead to full back only by moving the linkage or gears, because you move through the center and this will result in a complete change of all steam flow directions and a full cut off of the steam during the motion throught the center point...
For our steam locomotive this is dramatic, for a steam ship this is really nothing uncommon. But here the adhession betwen wheel rim and track surface prevent the wheels from intermediate change of rotation into the opposite direction and the pushing train won't make the things better! The keep the wheels turn still into the given direction, allowing no change without stop betwen... But the steam does not count on this, it goes into full stroke full force against the given direction and if steam can pull a huge freight train, it can play in such cases also chicken with the engine, so our unlucky engineer gets something, we here call "Spaghetti rods"... The steam force is so brute, that two opposite forces act with damaging effects to the rods and bars against each other... the rod bend or break and thus let the engine completely fail... and also will made the repair team to get a very unhappy task to do...

This we have to consider, and this is why on large engines a Johnson Bar won't be in service anymore. Our screw driven reverser will still move by those forces, but you do not have the problem to keep hold of it, and you can easily move it against all forces. Okay, agree: A browns engine or air driven valve gear adjustment is more comfortable, considering weight and mass of the gear of huge american steam locomotives - but a Johnson bar - no way.

BR&P wrote:"that is a correct meaning for company notch"

Which one - the most efficient, or the hardest working?

Most efficient, that which uses the least fuel (and perhaps fewer water stops as a secondary consideration) to move the consist at the desired speed.

steemtrayn wrote:I once read in an airplane magazine that a Johnson bar on a plane is used to control the pitch of the propeller blades, and that it got it's name from the reverse lever on a steam locomotive.

I don't think that is accurate though I can't be sure that in the dim past there was not such an arrangement. For planes with such variable pitch propellers (typically a somewhat more advanced aircraft) the control is not a lever but a knob typically adjacent to the throttle, that is rotated to vary the pitch. In smaller planes it is mechanically linked, in larger electric. Called the prop pitch control. In certain older light aircraft the angle of the flaps were controlled by a Johnson bar, and sometimes retractable landing gear and brakes.

My steam locomotive experience is very limited; but I have volunteered in the past to do "grunt" labor during boiler washes and annual inspections. I understand that the function of the "Johnson Bar" goes beyond setting the engine to go foward and reverse. This "reversing lever" adjusts the stroke of the valve gear allowing steam entering the cylinders to expand, and thereby not wasting it; a good combination of throttle and judicious use of the "Johnson Bar" is sometimes referred to as "hooking-up." Sort of like shifting gears on a manual transmission. From what I have witnessed, it would appear that this is achieved by listening, feeling and knowing the peculiarities of a particular engine. Did I get in the ballpark?

Let's see.
For a steam engine with a self-pressure balance piston valve for superior idle usually we start here:

From stop to go:
Open the throttle, watch the steam chest pressure. If is reaches 72 psi, carefully shift the gears from neutral to maximum - which is betwen 65 and 75%. So there is only a small cut off given, so expansion is very low and mainly the whole channels get openend and more then 2 thrids of more then 3 quarters of the stroke fresh steam with boiler pressure will enter the cylinder and dives the piston.
But with the low pressure, usually the engine will get in tension, the couple rods will stretch, but the engine won't really move.
Carefully open now the throttle more and more, till the engines starts moving. Pull the throttle to nearly shut, but to settle the pressure a little, reopen it and start carefully your speeding up.
Speeding up:
Carefully lower the gears to about 50 to 55% on the cut off scale, continue to open the throttle more and more... till to the open block. The throttle reamins open, as the engine accelerates to the desired speed. To force this, open the gear carefully a little more, but be aware of slipping!
Hold on speed:
If the speed is reaches for the travel and given shedule - carefully get the gears back to neutral. So you can reduce the steam feed to nearly 20 up to 35% depending on locomotive type and it's calm smooth run. I f you get below the minimum cut off, the engine will start shaking, rattling and act a little like a wild pony. So be aware not to get to low on cut off.
If the engine still accelerates, even with minimum set cut off - well, carefully pull the throttle in close direction, till the speeds is correct and the engine moves smooth and soft. Little corrections now are only done by adjusting the cut off to a little more or less feed.
Accelerating: Try to accelerate by throttle first: Reopen the throttle carefully, again if possible to the open block. If acceleration isn't good enough, adjust carefully the cut off to a more and pay attention to pressure and acceleration. Adjust the cut off and throttle again to hold on speed.
Speeding: Sometimes, speeding is desired. To do this, the engineer adjusts the cut off to a good point to have an acceleration, he has to keep the throttle on open block and opens the cut off more and more to keep the acceleration. Even above 55% on inlet, spend the engine some more, just to ensure a better timing, because as speed goes up, as less time the steam has to enter and exhaust, thus this negative timing, even on full channel openings requires to keep the inlet a little more open, to give the steam a little advantage in time, because now cut off comes more by speed and not by the gears.
For testing or emergency a skillfull engineer will advise his fireman to keep the fire up and feed water well before speeding to nearly maxmium. On speeding, the pumps were set on full stroke and the fire is kept up - now the engine is speed up as above, but on full set cut off on 65% stroke, the boiler pressure and cylinder pressure is now nearly a pipe connected passage, thus all boiler power is now send into the cylinders - which causes maximum power ooutput, but also maximum stress to the engine. For emergeny reasons or for speeding tests, this can be done... but not in regular service. This process quickly exhausts the boilers, will eat up the water in the boiler like opening the flush valve, but will boost the engine like a kick in the rear!
Going for idle: If idle is expected, carefully pull the throttle to close, reopen the cut off to nearly maximum, watch the steam chest pressure - it will settle down from working pressure to nearly zero. Now set the gears to nearly neutral position, a direction set of 5 to 10 % will reduce friction of the gear bearings, good engines can be kept at neutral.
From idle to speed: use the same procedure as for stop to go

That's it, if you have Trofimov piston valves...

Some engineers tend to on stop to set the gears on full, before opening of the throttle. So the opening of the throttle has then to be done very carefully, because the moving parts of the valve pistons will slide to their arresting holds, driven by the entering steam. To a distinctive 'klonk' noise will appear, and if one opens the throttle to roughly, the arrestor holds or the valve piston may break, causing the engine to fail.

If you have regular valves, here you go:

From stop to go:
Set the gears to the desired cut off, more than 62% is recommended. Carefully open the throttle. Watch for the tension and Pressure in the steam chest, maintain it low, till the tension get's loose and the engine does the first slow motion and the first calm woosh.
Carefully open the throttle more and more, but pull it back, to keep the engine from slipping... apply carefully more and more pressure by reopen the throttle more and more... Set back the cut off to 55 to 50% and open the throttle carefully till the open block...
All now as above mentioned for speeding of accelerating.
For idle: Carefully close the throttle and set the gears on neutral...
From idle to working: reopen the throttle to about 75 psi on steam chest pressure and set the cut off carefully to the desired value, reopen carefully the throttle...

The Company Notch was the most efficient position for the operation of the loco, using the least amount of steam, water, and fuel, saving the company money. On flat level track, with the train moving along well, the notch position was near the center, thereby working the least amount of steam, water, and fuel.

On Surry Sussex & Southampaton 2-6-2 #26, with Baker valve gear, at Pine Creek RR in NJ, the top forward position, one notch away from center / neutral, shut steam off for half of the piston stroke, pressurizing only one side of the piston, using half of the steam otherwise required.

trapper wrote:Many years ago i asked the same question. The answer i was given is that in the early days of steam, before
power reverse was invented or mandated, the term was "jouncin" as in bouncing around. This was because
as steam engines grew in size the associated parts of the valve linkage grew also. You can well imagine
in a typical large 2-8-0 of the early 1900"s the mass of metal that was moving around when the engine was
underway. When an engineer changed the reverse lever position to "notch" up or down he had to hang on
for dear life! Hence the term orignaly was "jouncin bar" which over the years morfed into Johnson bar.
Many enginers back then prior to power reverse suffered serious back injury from working on the large
brute steamers with no power reverse.
just my two cents

To back this up, a steel pedal is mounted on the floor of SS&S #26 for the engineer to brace himself on when hooking up the Johnson Bar while the engine is working. That lever does indeed "jounce".