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Author Topic: Live Steam  (Read 5726 times)
WGL
Great Northern


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« on: September 13, 2009, 03:17:58 AM »

 I'm looking at an LNER Class A4 4-6-2 Mallard Live Steam Set in HistoricRail catalog.  One fills the tender with distilled water & a "low voltage electrical heater in the tender safely heats the water & sends steam to the locomotive's drive cylinders for realistic operation."
 
 Do any of you steam devotees have a live steam locomotive?  I wonder how they run:  how long on a fill & how fast.
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hotrainlover

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« Reply #1 on: September 13, 2009, 09:38:12 AM »

I helped my Dad build a NYC 4-6-4, when I was 12.  We recently put in new boiler tubes.  The engine takes about 1 and 1/2 hours just to draw the heat enough to have "Just running " pressure.  This is live coal, and should take longer, anyway.  The one in Historic Rails should work.  I just would not want all that moisture on my layout.  You would have to keep it lubed really well, though....  The heat causes the rod bearings to loose their lubes....
You could always add a water tender....  But I do not see how one could "Pump" the water to the engine. Grin
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Cooped


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« Reply #2 on: September 13, 2009, 09:52:05 AM »

According to the Hornby website, with some practice one load of water should last for about 20 minutes of run time, it doesn't say how fast. There are several movies of these things running on youtube so they certainly work. I have the Flying Scotsman version on my list for Santa.
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Yes dear, I'm looking at trains again........
renniks


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« Reply #3 on: September 13, 2009, 11:34:25 AM »

I have 5 scratchbuilt Large scale gas fired locos which run 35-45 minutes on one gas fill.
Have no experience of the Hornby OO scale model but judging by the numder of years it has been in production, it must be reasonably efficient. Rather different to their 3 1/2" gauge model of the "Rocket"which was almost useless.

Eric UK
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #4 on: September 13, 2009, 02:21:53 PM »

As already pointed out, the time to fill them up is less than the time to heat them up.

As far as speed is concerned, live steamers usually run too fast unless you can continuously monitor the throttle.  This is because it takes more steam to start than to run, so opening the throttle valve just enough to start means it is open enough to run quite quickly once it does start.  There are three common solutions to this problem:
(1) Run after your locomotive, trying to adjust the throttle without stalling the locomotive or knocking it off the track.  This method usually gives observers a good laugh and convinces them to stay with electric motors.  This is the method most often applied to pot boilers with oscillating cylinders and throttle only speed control.
(2) Ride behind the locomotive, typically by sitting on the tender, so that you can keep one hand on the throttle and the other on the Johnson bar.  This requires a large locomotive and track, which is relatively expensive, particularly when you use 7-1/4" or 7-1/2" gauge or larger equipment.  Ride behind is possible down to about 3-1/2" gauge, but then you need elevated track so your legs can dangle down when you straddle the tender or a flat car.  While that is generally fine with the live steam people, it generally looks ridiculous to the electric motor crowd.
(3) Radio control of at least the throttle and preferably of the Johnson bar as well.  This works particularly well in 1-3/4" gauge ("G-scale") which is large enough to house the radio equipment and controls without overly compromising appearance but still small enough to run in a typical back yard.

As you have probably gathered from the above, some live steam locomotives are fitted with Johnson bars while others are not.  The Johnson bar controls the point where steam is cut off from being sent to the cylinders.  Late cut off, where steam is admitted to the cylinder for virtually the full stroke of the piston, gives more power but uses a lot of steam.  Early cut off, where just small puffs of steam are admitted to the cylinder at just the beginning of the stroke saves a lot of steam once the locomotive is rolling.  With late cut off, it is the pressure of the steam that turns the wheels.  When the cylinder exhaust port opens, the steam leaves the cylinder at almost full pressure (thus the sharp bark of the exhaust.   With early cut off, it is the expansion of the steam that turns the wheels.  When the exhaust port opens, the steam exiting the cylinder is barely above atmospheric pressure (thus the quiet swish of the exhaust when running easy or decelerating.

I explained the job of the Johnson bar - to save steam - because having or not having a Johnson bar and its associated linkage has a very major effect on how long a locomotive can run without adding more water.  No Johnson bar is like running your car permanently in low gear -  you use lots of fuel (and water.)  A Johnson bar under the control of a good engineer is like having overdrive - you get much farther on a gallon of fuel (and water.)

A more obvious way of lengthening run time is to have a water tank and a water pump.  The tank is usually where it should be - in the tender - but sometimes in a water plug.  For ride on trains, there are lots of possibilities for pumps - manual, mechanical, steam driven or even injectors.  For smaller locomotives, mechanical pumps driven off an eccentric on a tender axle seem to be popular.  And for the little pot boilers, no pump at all.  Fuel can be wood, coal or propane for ride ons, usually butane for R/C and often solid fuel for pot boilers.  Bottom line, given a Johnson bar to control cut off, a water tank with pump, and compressed gas for fuel, running times over an hour are achievable in the smaller locomotives and multi hour running times in the larger ride ons.

Jim
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hotrainlover

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« Reply #5 on: September 13, 2009, 03:49:48 PM »

I did fail to mention that this engine is 7' -1/4 inches across the rails.  We ride on the tender and adjust the controls manually.  It also weighs approx.  3-4 thousand pounds   Grin 

One could use a small water pump that works on DC current to get water from a auxiliary water tender.  Problems solved.
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #6 on: September 13, 2009, 06:48:37 PM »

I suspect an electric pump would make the boiler inspector frown.  The thought of the water dropping near the crown sheet and the battery going dead at the same time ... how fast can you run?

Seriously, I don't know what inspection procedures apply in your part of the world, but up here they are pretty strict.  Any boiler over 6" in diameter is subject to yearly inspection and testing.  And one of the requirements to pass inspection is to have two independent means of filling the boiler with water while under pressure.  One injector and one hand pump is acceptable.  I have heard that the inspector may in some cases accept a single pump on a small boiler if it is possible to immediately dump the fire when the pump fails.  I suspect that would limit the locomotive to oil or gas firing.

I also suspect that using an electric pump to pump water from a water plug (auxiliary tender or tank car) would be okay if there was some way to assure the auxiliary water was used up before the tender water, and if there were the required number of pumps between the tender and the boiler.  I will have to try to remember to ask the inspector the next time I see him.

Originally I got my steam license on a steam tractor.  One of the questions we were asked was how high up the tractor would go if the boiler were to sudden burst and direct all the energy straight down.  Anybody want to take a guess?

Jim
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Growing older is mandatory but growing up is optional.
WGL
Great Northern


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« Reply #7 on: September 14, 2009, 02:05:33 AM »

Thanks for the information.  Coop, I hope that you will report how your Flying Scotsman runs.
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Joe Satnik


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« Reply #8 on: September 15, 2009, 12:18:14 PM »

Bill,

Charlie S. and Bill A.  downtown here are the biggest US train shop sellers of that Hornby OO scale electric powered live steam Mallard. 

Quite a number have been sold locally.   

(People all over the country know that Charlie knows and stocks British outline trains.)

http://www.hornby.com/live-steam-157/r1041/product.html

Contact Charlie.   He may be able to set up a demonstration.

http://modeltrainclassics.com/Hornby.html

Also, do a search on the Bachmann Board, and elsewhere if you want, for reviews of Historic Rail.  If I recall correctly, not all were positive, due to back-orders and cancellations. 

Hope this helps.

Sincerely,

Joe Satnik   

 
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If your loco is too heavy to lift, you'd better be able to ride in, on or behind it.
WGL
Great Northern


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« Reply #9 on: September 16, 2009, 02:11:05 AM »

Joe, it's nice to hear from you.  Thanks for the information.

 It would be fun to see a demonstration, but I don't plan to spend $600 for a live steam locomotive, plus about $50 each for passenger cars.  I wonder if they ever demonstrate live steam at the local train show.   I enjoy Historic Rail's catalog, but I haven't ordered anything from them.  Thanks for the cautionary tip.

 I haven't bought any train stuff for 3 months!
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Joe Satnik


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« Reply #10 on: September 16, 2009, 04:37:50 PM »

Dear Bill,

Time for a train show !

Indianhead show at Regis in Eau Claire is coming up October 10 and 11.

Joe
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If your loco is too heavy to lift, you'd better be able to ride in, on or behind it.
WGL
Great Northern


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« Reply #11 on: September 17, 2009, 02:58:29 AM »

Joe,

 I have the date on our bulletin board.  I'm still wishing I'd gotten the HO water tower I saw at the show in Menomonie.  I'd like an HO '50s greyhound bus, but $20 is a bit steep.

Bill
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