Locomotive's Optimum Weight

[Jim Banner]

Another use for sand is to clean the flues in a steam locomotive.  A couple of shovels of sand thrown in the firebox will go swirling through the flues and up the chimney, taking soot and creosote with it.  Then the heat transfer from the hot air/flames to the water is much improved.  This also helps clean coal dust and stuff off the shovel, getting it ready for cooking the bacon and eggs for breakfast.  No, they don't use steam cylinder oil for greasing the shovel - that was what the bacon is for.

While on the subject of breakfast, you also need to know about the metal shelf attached to the back of the firebox.  Officially, it was to keep the oil cans warm in cold weather so the oil wouldn't be like molasses.  Unofficially, that was where the coffee pot was kept.  Back in the days before water treatment, hot water for coffee or tea was drawn from the bottom tri-cock.  Now you know why there are three when two would do.  Cream for the tea and coffee as well as the eggs were often from a trackside farmer who would from time to time get one of the crew to pick up something from town, or maybe deliver something.

I can't swear to any of this, except the bacon and eggs on a shovel and the shelf for the coffee pot.  It is all rumour from a long time ago when schedules were looser, trains were shorter, speeds were slower, and superintendents were fewer and farther between.   I suspect the railways were aware of what was going on but chose to ignore it as long as the freight arrived reasonably on time and nobody was booking off sick from stomach problems when 100 miles days turned into 20 hour days.  I also suspect that the superintendents were fellows who had come up through the operating trades, not university boys who would faint at the thought of working 12 hours of overtime on top of a a full day's work.

[pdlethbridge]

That reminds me of a picture of a B&M switcher carrying a block of ice on the pilot. Don't ask me why.

[WGL]

The optimal weight for a model locomotive, without traction tires, is to cram as much weight as you can into the body shell, keeping the weight balanced around the centre of the driving wheels on steam, so that the loco can still spin it's drivers under full throttle.

If the loco cannot spin it's drivers under full throttle, then you risk motor burnout so remove some weight.  Traction tire fans, please note that little tit-bit.

  That's a simple formula to remember.  I guess it's okay if, at full throttle, the steamer moves at 130 mph, instead just its wheels.     BLI informed customers that metal drivers are available to replace the wheels with traction tires that came on our Heavy Mikados.

  Jim, that's some colorful train lore!

Stephen, now I'll now those aren't anthills.   

[Woody Elmore]

My first HO kit engine was an original Penn Line mike. I built it as instructed. When I joined a large HO club I brought my engine along to run. It was greeted with much disdain as the club members told me that my mike would barely pull five cars. The reason, of course, was the heavy tender and trucks that didn't have the best rolling qualities. It was quite a disappointment.

If I remember from my days in HO weight in an engine needs to be over the driving wheels and balanced. Sticking lead in a cab roof might make an engine heavier but it is just adding drag.

[rogertra]

  That's a simple formula to remember.  I guess it's okay if, at full throttle, the steamer moves at 130 mph, instead just its wheels.    

Spinning wheels under full throttle has nothing whatsoever to do with the top speed.  If the loco's top speed while running free is a scale 55 mph, then you fill it with weight enough so that under full throttle, the wheels will still spin. 

Speed has nothing to do with it.

[rogertra]

My first HO kit engine was an original Penn Line mike. I built it as instructed. When I joined a large HO club I brought my engine along to run. It was greeted with much disdain as the club members told me that my mike would barely pull five cars. The reason, of course, was the heavy tender and trucks that didn't have the best rolling qualities. It was quite a disappointment.

If I remember from my days in HO weight in an engine needs to be over the driving wheels and balanced. Sticking lead in a cab roof might make an engine heavier but it is just adding drag.

That's what I wrote: -

" ... keeping the weight balanced around the centre of the driving wheels on steam..."

[lmackattack]

  gravity does not scale 

look at the front and rear trucks of a steamer. if they have a spring that pushes down on the truck it removes weight from the drivers.you can cut a coil or two out to get more weight on the drivers. one thing alot of people think is that the more drive wheels a loco has the better it will pull.. this is not always true... if the weight is the same between a 4 driven axels and 6 driven axels  the 4 axel will likely pull better. this is also tru with steam..

[Yampa Bob]

Here is a bit of information about "Adhesive Weight".

http://everything2.com/e2node/adhesive%2520weight

The total weight of a train includes both the cars and the locomotive. Therefore a percentage of available power is lost just moving the locomotive. For the way I operate, I estimate about 20% for the loco. Of course I only run short trains.

[lmackattack]

thats a great link Yampa! that about sums it up about traction and weight

[Yampa Bob]

I thought you would like it. The section about steam locomotives is interesting.  All drive wheels coupled together gives "total adhesion" but lack stability at speed.

Here's another good site, scroll down to "running gear".

http://www.answers.com/topic/steam-locomotive-mechanical-engineering

Site also has a great animation and lots of other information about steamers.

[lmackattack]

Another great link about the workings of steam engines!

Locomotives with "compensating levers" connecting the ends of plate springs have often been deemed a complication but locomotives fitted with them have usually been less prone to loss of traction due to wheel-slip.

is this compensating lever a way to balance weight across drivers or does it give one axel the ability to have a greater weight on it?  intresting read!

[WGL]

Bob,
  I read with interest your links to adhesive weight & steam locomotives.  However, I don't understand why, if a 0-4-0 has the same weight on each axle as a 2-10-2 ("Also known as Santa Fe class locomotives, these brutes were typically employed in drag freight service."), the bigger locomotives were used to pull longer trains.   

[pdlethbridge]

The axle load was limited by the track the engine ran on. A high axle load engine such as the C&O 2-6-6-6 Alleghenies required the heaviest rail made to support the train. Some areas in Canada, for instance, used very light rail and used diesels with 6 axles rather than 4 to spread the weight.   

[Eryalen]

That reminds me of a picture of a B&M switcher carrying a block of ice on the pilot. Don't ask me why.

It's the coolest place on the engine to carry it.

[lmackattack]

Bob,
  I read with interest your links to adhesive weight & steam locomotives.  However, I don't understand why, if a 0-4-0 has the same weight on each axle as a 2-10-2 ("Also known as Santa Fe class locomotives, these brutes were typically employed in drag freight service."), the bigger locomotives were used to pull longer trains.   

a 0-4-0 switcher can have the same axel weights as a big Santa Fe class and is able to push around heavy trains but it cant maintain the movment for a long time.  reason is that the 0-4-0 is not a large engine and has a smaller firebox and boiler.. the larger 2-10-2 has a larger boiler and firebox so it can maintain its steam and thus move the freight at a higher speed and a further distance. each engine was built for a diffrent service even tho they basicly can pull the same weight