Home Open Account Help 237 users online

Steam & Excursion > Running a steam engine

Pages:  [ 1 ][ 2 ] [ Next ]
Current Page:1 of 2

Date: 11/28/02 08:27
Running a steam engine
Author: MTMEngineer

Digging thru my archives, I ran across this item that I posted on another BB some time ago. How to run a steam engine...

As an engineer and trainer for the Minnesota Transportation Museum, operating the Osceola & St. Croix Valley Ry out of Osceola, Wisconsin, I thought maybe some of you might find it interesting to hear a description of what actually goes on in the cab of a steam locomotive when running.

If you visit the Twin City area, you\'ll find the OSCV crews very friendly and will do all they can to make you feel welcome at our operations or restorations.

Though we run diesel power most of the time, we bring out locomotive N.P. 328 for some perations. She\'s a slide valve 4-6-0, hand fired, with Johnson Bar reverse, Stevenson valve gear, 175 psi boiler pressure, saturated steam, and 57" drivers.

Sitting in the station, the automatic air brakes (the brakes on the cars of the train) are in the release ("running") position, and the independent
brake (the air brake on the locomotive and tender) is in the fully applied position to keep things from rolling away unintentionally. The sight feed lubricator is set to the off position so as not to waste oil, which is administered to the cylinders while running, literally a drop at a time. (Master Mechanics used to treat oil like gold, and ranked engineers by how little oil they used.) The reverse lever ("Johnson Bar") is centered, the cylinder cocks are left open, and the throttle just cracked. This admits a bit of steam into the cylinders to keep them warm when not running, but does not generate enough force to overcome the independent brakes.

During this time, the engineer can "count the parts", "oil around", refill the lubicator if necessary, check for warm bearings, and otherwise
make sure everything is as it should be. If the consist of the train has been altered in any way, brake tests must also be made under the direction
of the conductor or brakeman.

The fireman spends this time preparing for the departure. The water level must be high enough to completely cover the crown sheet (the inside
"roof" of the firebox) but not so high as to significantly reduce the amount of space available in the boiler for steam storage, nor to allow water to be lifted into the dome and thus into the cylinders upon starting. The fire must be low, so as to not cause the "pops" (safety valves) to open, but must have a good bed of coke, ready to put out a lot of heat the moment the train starts up. Too much and the draft will be choked off - too little and the draft will literally tear holes in the bed of the fire upon starting. The surest way to ruin a firemans day is to delay the departure of a train that\'s ready to go. The blower is on just enough to keep air moving through the flues - but no more. The firedoor is kept closed as much as possible, so only air that has been heated by the fire enters the flues. This helps keep temperatures even and reduce leakage of flues and staybolts.

Water level is the responsibility of the fireman. It\'s put into the boiler with an injector - a marvelous device that takes steam from the boiler, mixes it with water from the tender, and forces it back into the boiler through another pipe - with no moving parts!!!! These things impress me. I know, thermodynamics says they work, and in actual practice
they do work - but intuition says "No Way!"

OK. The stationmaster radios "Stationmaster to NP 328. You\'re clear to depart." The conductor shouts "All aboard," and gives a highball
sign. The engineer acknowledges with two short whistle toots, and starts the bell.

The engineer releases the latch on the quadrant and drops the reverse lever into the full forward position - "in the corner." The fireman shuts
off the blower and throws about 3 scoops of coal into the firebox. The engineer turns the lubricator on, turns on the sanders, and gives a
gentle tug on the throttle, then feathers off (releases slowly) the independent brake so the slack stretches out gently. Once things start
moving, the engineer can move the throttle out quickly, only being careful not to slip the drivers. Slipping the drivers damages track and running gear, and the sudden draft can tear holes in the finest firebed. The engineer uses four of his senses to coordinate everything - sight, sound, smell, and feel. If the engine is going to slip, he\'ll feel a slight sideward movement of the back of the engine a split second beforehand. At that, reducing the throttle will prevent a slip.

Within about 10 seconds he\'ll have the throttle wide open, and the engine is accellerating in full cutoff - that\'s with the Johnson Bar in
the corner. When he feels, or hears, that the rate of accelleration may be decreasing, it\'s time to "hook up" the Johnson Bar. The reason for this, is that when starting the engine is running with maximum cutoff. For a slide valve engine, maximum cutoff is usually 100%, but may be lower, down to about 90%, but the maximum for any particular engine is fixed by the setup of the linkage at the shops. 100% cutoff means that for the full power stroke of the piston, steam is admitted into the cylinder, and full boiler pressure is applied to the piston. This gives maximum power, but is possible only at low speed due to the limited ability of the boiler to generate steam, and of the piping to supply it to the cylinders. 80% cutoff means that for 80% of the stroke steam is admitted into the cylinder, and for 20% of the stroke the expansion force of the steam in the cylinder pushes on the piston.

Hooking up the engine requires care and strength. The full boiler pressure is pressing each of the slide valves down on their seat with a force of up to 15 tons, though this is reduced somewhat by a balancing mechanism on the back of the valve, it is still considerable. Those
valves don\'t want to move, so when the catch is released on the quadrant it takes a firm hand to prevent the reverse lever from jumping about
wildly. I usually place my right foot at the position on the quadrant to which I want to move the lever, firmly grasp the lever and squeeze
off the latch. The motion of the engine will push the lever back towards me, and the mass of my body will slow it down. When it hits my foot
I release my grip on the latch and the lever is locked into its new position.

With the lever hooked up, the engine sort of "breaths" a bit easier. The exhaust becomes crisper, and the engine continues to accellerate.

After about 15 or 20 seconds of running, the cylinders are fully warmed, and cleared of any condensation, so the cylinder cocks may be closed. The sanders may be turned off.

About this time, we\'re far enough from the station to turn off the bell, too.

If the Johnson Bar had been pulled up too far, the engine would start to seem sort of wimpy, since the steam starved cylinders wouldn\'t have
sufficient steam for expansion. Thermodynamics could tell us exactly the ideal position of the Johnson Bar at any time, but experience is
heavily relied upon here.

The Johnson Bar may need to be hooked up several times before maximum speed is achieved. If track speed is reached before the optimum position
of the Johnson Bar is found for most efficient running, then the throttle may be closed a bit. But, as much as possible, you want the expansion of the steam to take place in the cylinders, not in the dry pipe.

During this time, the fireman has been very busy. He\'s not shoveling constantly, though. You never put in more than 3 or 4 scoops of coal
at a time. Then wait 15 or 20 seconds before putting in another 3 or 4 scoops. The firebox temperature has risen from about 900 degrees F.
to almost 2500 degrees while starting out. A scoop of coal weighs about 15 lbs. Five lbs. of that is volatile gasses trapped in the
coal, which is "cooked out" of the coal within the first 15 seconds of entering the firebox at that high a temperature. If more than 4 scoops is placed on the firebed, the volatiles that are cooked out will not have enough oxygen for complete combustion, part of the available energy will be wasted, and the smoke turns black. What
remains on the grate after the volatiles is cooked out is about 5% ash and other waste, but the rest is pure carbon coke, which will be
consumed on the grate in about 3 minutes. It is therefore necessary to maintain a steady pace of placing 3 or 4 scoops every 15 or 20 seconds, then waiting. All of the coal in the firebox must be replaced every 3 minutes.

One up to speed, it\'s usually not difficult to keep her hot.

Between periods of firing, the fireman checks his boiler pressure and water level, adding water whenever necessary with the injector. Water
level is very important. Remember that firebox temperature of up to 2500 degrees? Well, steel melts at about 2000 degrees, so it is necessary to maintain at least 4 inches of water on top of the firebox to cool it, or the crown sheet (the roof of the firebox) will soften and collapse downward - the classic boiler explosion. He also keeps a lookout for signals, and confirms ignals, track conditions, and grade crossing safety with the engineer.

There are two things he must guard against while tending the fire: clinkers and holes. A clinker occurs when the firebed melts and fuses into a gooey mass that will not allow air (oxygen) through it. A hole can be caused by uneven distribution of coal while fireing, by having
too thin a bed of coke on the grates so the draft tears a hole in the bed, or by slipping wheels or mishandling of the Johnson Bar. In any event, these conditions cause a reduction of firebox temperature, and a relultant loss of steam generating capacity.

Stopping the train smoothly requires as much, or more, skill on the part of the engineer as starting it.

Approaching the station, the throttle is shut off, then opened a crack to keep lubication flowing into the cylinders. The automatic air brake is applied, first with about a six psi reduction from the 90 psi that was carried while running. Setting the automatic air also sets the
independent brakes on the engine, so a separate release of the independent brakes is made, which keeps the slack stretched out. A second four or five psi reduction is made with the automatic air, and the independent again released. The engineer plans this application to stop the train about 100 feet short of the ultimate stopping point.

When speed reaches about 5 mph, the Johnson Bar is again dropped into the corner, and the cylinder cocks opened. The brakes are released for about 4 seconds, followed by a brake reduction to about 75 psi and the independent brake released. If the train is stopping too soon, the throttle may be opened a bit more.

Just before or at the instant of stopping, release the automatic brake, fully apply the independent brake and shut off the throttle. You\'ve just made a perfect smooth "two application stop."

Don\'t forget to shut off the lubricator.

Date: 11/28/02 13:25
Re: Running a steam engine
Author: nycman

Applause, applause! Very good stuff there. Running steam ain\'t like pulling the handle to run 8, is it? Happy Thanksgiving.

Date: 11/28/02 15:54
Re: Running a steam engine
Author: steambrake

Thanks very much for posting that. I don\'t think most people realize the great balancing act going on up there in the cab.

Date: 11/28/02 19:37
Re: Running a steam engine
Author: ge13031

Very well done, clear and concise, even a diesel dummy like me could understand that and with about 15 years experience could do that too!

My favorite steam passenger trip was from Bala, Ontario to Toronto with a many coach train on the CP. The conductor let us ride in the baggage car so we had a front row seat right behind the tender. The train was heavy enough to require a heavy pacific in front of the light pacific that usually handled the train. Starting up from the second station, the heavy pacific blew a cylinder head (visible 150ft in front in the ditch) and had to be cut off at the next siding. The light pacific took us the rest of the way to Toronto making up time as he went. That locomotive was working its heart out with some pretty heavy starts and stack talk the whole way. This was a real milk train stopping everywhere and we got a great chance to see some real professional train handling.

Date: 12/01/02 16:12
Thanks for posting
Author: brassjournal

This is an excellent account, lots of information in a small package.

It is a "keeper" and I\'ve printed it for further review.

Thanks for posting it for us.

Date: 12/01/02 16:52
Re: Thanks for posting
Author: MTMEngineer

Well, you\'re all very welcome.

If this raises more questions than it has answered, I\'d be pleased to try to answer them, if I can.

Date: 12/01/02 17:06
Re: Running a steam engine
Author: NYCSTL8

Wow, what an account! I\'m trying to picture the hogger and ashcat on a hand-fired, Johnson bar K-4, moving out on a miserable winter night such as this one in Ohio with No. 28 on the drawbar, wind howling, snow and sleet pelting, and those amber position-light signals showing the way. Gonna be hard to see the sign telling you where to lower the water scoop, and that trek back over the coal pile to check the water level is going to be a lot of fun too. Hope the fire hangs on til you can get back to the shovel. Talk about earning your keep! A belated toast to all the men who kept \'em rollin\'!! Jim in Wapak, OH, on the B&O.

Date: 12/01/02 18:03
Re: Running a steam engine
Author: MTMEngineer

NYCSTL8 said:

>I\'m trying to picture the hogger and ashcat on a hand-fired, Johnson bar K-4, ...<

Let\'s see... B&O K\'s were 2-6-0, but I suspect you were talking about PRR. In that case, I don\'t think they had Johnson Bars, but rather a screw reverse. Now THAT would have been a real PIA!

Date: 12/01/02 19:41
Re: Running a steam engine
Author: grande473

Check the special collections portion of the DOT website. There was a case in the Locomotive Inspection section where a hoghead broke his wrist when a reversing screw went wild. It was on the New York Central I think.
The Locomotive Inspection secton also has boiler explosions reports like one where witnesses state they saw a Norfolk & Western Y-5 boiler flying over the treetops courtesy of 51 square feet of overheated crown sheet.

Date: 12/02/02 07:02
Re: Running a steam engine
Author: NYCSTL8

I was speaking of the PRR K-4. You are right about the screw reverse on the early K-4\'s. Could you describe the operation of that mechanism vs. the Johnson Bar? In the other post about the NYC engineer breaking a wrist, I wonder if that refers to the wheel-controlled power reverse arrangement common on NYC power. Thanks. NKP 8 out

Date: 12/02/02 08:36
Re: Running a steam engine
Author: MTMEngineer

NYCSTL8 wrote:

> I was speaking of the PRR K-4. You are right about the screw
> reverse on the early K-4\'s. Could you describe the operation
> of that mechanism vs. the Johnson Bar? In the other post about
> the NYC engineer breaking a wrist, I wonder if that refers to
> the wheel-controlled power reverse arrangement common on NYC
> power. Thanks. NKP 8 out
I\'ll post a copy of the prints after I get a chance to scan them this evening.

Date: 12/02/02 13:42
Re: NP 328 as seen trackside
Author: st.croix334

Great stuff MTMengineer, Here is a look at the 328 for everyone to go along with the excellent description of what makes it go. Quite the handsome little locomotive.

Date: 12/02/02 16:45
Re: NP 328 as seen trackside
Author: MTMEngineer

Nice Stack!

Wonder who I had firing for me that day. <G>

Date: 12/02/02 18:17
Screw reverse
Author: MTMEngineer

It\'s hard to understand how one could hurt himself on one of these things, but I guess Murphy\'s Law must be valid.

Date: 12/02/02 19:34
Re: Screw reverse
Author: nycman

MTM, I was waiting to see that drawing, and it sure looks exactly like the NY Central reverser control. On the NYC, that merely controlled a servomechanism which then did the heavy work of moving the reverser control arms. It was 16 full turns from full forward to full reverse. The control "wheel" had a lock, which you had better set. If not, and a rod broke or some other part of the mechanism failed, the "feedback" would cause the cab control wheel to spin wildly, and if you had your hand in it, could get hurt.

Date: 12/02/02 20:04
Re: Screw reverse
Author: MTMEngineer

Both the lever action or a screw action mechanism could be used with or without a "servo".

Because of the force required to move the valves, without a power reverse "servo", the Johnson bar was about 4-6 feet long. When unlatched from its quadrant, it MUST be held onto tightly - or personal injury is virtually guaranteed.

With power reverse, the lever need only be about 14" long.

The advantage of the screw is safety, over the Johnson. However, its disadvantages in slowness of changing direction and it it\'s relative inflexibitity which caused damage to valve gear linkage made it generally unacceptable for US railroads (except PRR and NYC), though it was widely used in most of the rest of the world.

Date: 12/03/02 04:22
Re: Name this part...
Author: steambrake

ok, what is this...and what type of locomotive is it on?
Hint: since there is not much in the photo to give any scale, the item seen here is about 4 feet long!

Date: 12/03/02 04:30
Re: Name this part...
Author: dcbailey

Well, the gizmo at the upper left is a Detroit DV-7 mechanical lubricator, and it appears to be chain driven. The 4 foot long thing you refer to is a chainguard.

Date: 12/03/02 06:06
Re: Name this part...
Author: MTMEngineer

That one\'s easy. Right side, front engine, Union Pacific 4-8-8-4 or Challenger.

The bicycle chain transmits the oscilating motion of the Walschaert link to the lubricator. Usually, this motion is transmitted by levers, and was taken from the action of the combination lever right behind the valve chamber. UP seemed to like to take the action from the link, as shown. I\'d suspect that their thinking was that the links motion would be the same for all settings of cutoff, whereas the normal method would reduce the motion at shorter cutoffs.

Date: 12/03/02 09:28
Re: Name this part...
Author: steambrake

Yes, absolutely correct once again! (I\'ll post a slightly wider shot next).

The photo is Steamtown\'s UP Bigboy 4012.

Pages:  [ 1 ][ 2 ] [ Next ]
Current Page:1 of 2

[ Share Thread on Facebook ] [ Search ] [ Start a New Thread ] [ Back to Thread List ] [ <Newer ] [ Older> ] 
Page created in 0.1421 seconds