Would someone explain the use of a Johnson Bar for me? I'm not sure that I spelled that correctly. Thanks [This message has been edited by Patrick (edited 23 March 2000).]
I may be brain dead on this, but where, how and what did this come from. I'm trying to scratch my head to figure it out and come up blank. Is it a term from the east coast or maintance in the way or is it the old hang out where the conductors end up after a trip? Need more input.
Hello Throttlejock, I don't think the person that asked me was refering to a watering hole. They asked if I knew what this lever in the cab of a steam locomotive was used for and they said that they thought it was call a Johnson Bar. Had to do with possibly controlling forward and reverse. It would be nice to have a glossary of railroading terms available for us rookies. What has really got me started in being a railfan is the book Tehachapi by John R. Signor which I am now reading. Thanks for your time Throttlejock. ------------------ Tehachapi [This message has been edited by Patrick (edited 23 March 2000).] [This message has been edited by Patrick (edited 23 March 2000).] [This message has been edited by Patrick (edited 23 March 2000).]
Patrick, I was looking for an idea where to start looking for the johnson bar. Now we have it narrowed to steam engines. That is before my time and having only been in a few steam cabs I'm not sure but I think if you were to post the question in the steam forum they might be able to find out for ya. I will look through my meager collection for any refrences about it and post if I find anything.
In answer to the question of the Johnson Bar. The johnson bar controlled the forward and reverse movement of the steam locomotive. It was located in the cab infront of the engineer. It was a long bar that attached under the cab floor to a bracket and extended upward into the cab. It moved in a forward to reverse position. When the engineer wanted to go forward he would grab the lever release the locking trigger and puch it forward. This was connected to the valve motion which would cause the slide valve or piston valve to change positions. From this moving of the johnson bar the engineer could control the direction the locomotive would go. I hope this answers your question. ------------------
Patrick ... Steamer gave the correct answer about the Johnson Bar's function. A little more info about it: In the early days of steam, the JB was approximately 6 feet high and it took 3 men and a boy to move it. With the advent of the air / steam assisted reversing cylinder, the JB was shortened to about 3 feet in height because it could now be moved fairly easily. The JB has three basic positions: Forward = forward movement of the locomotive; back toward the engineer = reverse and the middle position of straight up and down = neutral. When the JB is pushed all the way forward, (or back) the steam cylinders are at full stroke ... thereby use the maximum amount of steam supplied by the throttle. After the train gets moving and up to speed, the JB can be moved back toward the middle resulting in a shortened power stroke in the steam cylinders, which results in reducing steam usage, (much to the delight of the fireman) and also results in a reduction in fuel consumption. This modified or shortened position of a JB is called, "in the company hole." Hope this additional info helps you out. Bill
so you could compare the jb to a car with an automatic transmission. it had a forward and reverse,netural,and as your speed increased you had the ability to shorten the stroke as overdrive. or something like that ljb
LJB .. I don't know if I'd go as far as to compare the function of a JB to an automobile's automatic transmission, because there's nothing automatic about using a JB. It is truly an application by the steam locomotive engineer's sense of when and how much to shorten the stroke of the steam cylinder ... and that is done by 'feel and sound' of the locomotive as it pulls the train. For the most part, running a steam loco is done by the seat of the engineer's pants, and each loco has it's own personality. They are very much like a woman ... sometimes easy to get along with, while other times, because they can be fickle by nature, they can easilly kill you. *grin* It might be more accurate to compare the function of the JB as how a machinist might change the speed of a lathe by selecting a different pully. It has to be a consciencious thought to do so by the operator and then must be done manually until it 'feels' right to get the job done. Bill
We called it the Company Notch because our JB's 'trigger' (lock) engaged a sector 'gear'. The stroke of the pistons did not change, but by locking the JB a couple of notches off center foreward, very little new steam was introduced into the cylinder at eack stroke. Because steam expands at 800 to one, you were "riding the expansion" which saved your steam volumn. If you started up hill, you would give her another couple of notches, then when starting down you could take a couple or more notches back. Also, a steam engine's brakes do not stop it when just barely rolling like you can a car. To 'spot it' or stop on a dime right under the water or coal tipple, the engineer lets the engine roll , then sets the JB at center, then he can give it a notch of reverse to stop. The responce is instant. With steam you have full horsepower at all times. A car has gears, but a steamer doesn't need them. Like an auto, a diesel engine has a motor that only develops it full horsepower at above ideling speed. The first gear allows the motor to 'revup' (speed up) while delivering a lot of horsepower to the rail but at slow speed. A steam engine has to have a 'full head of steam' to run, so it delivers all its horse power just as soon as the throttle is cracked open. It is general practise to back up and 'bunch' all the cars, then start out foreward to start a train. If a train's total load is 8,000 tons, only four or five engines were built that could start that load from a standing start. But, even an empty box car weights 100,000 pounds, and can be started and rolled slowly by a pickup truck, but it does not have the horsepower to roll the box car at a high speed. Almost any diesel can start a train, but only one engine does not have the power to get the whole train up to a fast speed, nor pull it up hill, so diesel engines are added. A small steam engine can start the whole train, but for the same reason sometimes there were helper engines added to the front, middle, and back. The huge steamers were built to handle the long trains alone, that today require 5 to 8 diesels to handle. The comparison to an automatic transmission, is if the Johnson bar on a steam engine was pushed to full foreward, and the throttle was jerked wide open, the drivers would instantly slip spinning wildly heating up red hot. The weight of the engine, inertia, momentum and all that. If you jerked a diesel's throttle wide open, the motor would quickly begin to wind up and the diesel would begin to roll away before its wheels slipped. You would have time to shut it off before ruining the wheels, on a steamer you wouldn't. ------------------ Watash [This message has been edited by watash (edited 29 October 2000).]
<BLOCKQUOTE>quote:</font><HR>Originally posted by watash: We called it the Company Notch because our JB's 'trigger' (lock) engaged a sector 'gear'.<HR></BLOCKQUOTE> Thanks very much for the explanation Watash. A friend of mine here at work and I are still talking about the the Johnson bar and I'll give him a copy of your post. Always enjoy your comments on the Board. Patrick ------------------ Residing in BNSF's St. Croix Subdivision near Trempealeau, WI
The Johnson Bar was usually long enough to extend through the cabin floor to a pivot. There was a rod running up to the handle end that was hooked onto another handle pivoted about like a pair of pliers, or the hand brakes on a motorcycle. When you gripped the movable handle, the rod raised up pulling a piece of metal that looked like a gear rack, small 'teeth' along the bottom. It meshed with a large section of a gear. This allowed very fine adjustments to be made between wide open and completely shut. This controlled how much the steam valve opened and closed each time the piston made a stroke. The most effecient 'notch' was used the most often, so was worn enough to be easily seen, and became known as the Company Notch. You didn't work your firemen to death, and you didn't waste coal or water. The company was happy with you too. The same apparatus was used on farm plows to set the depth the plows were to go into the soil, or how deep to plant, etc. I'm planning a small scale version to operate the throttle on my HO power pack. ------------------ Watash [This message has been edited by watash (edited 04 November 2000).]
