6 replies to this topic

[NSwanberg]

Was it mentioned that Big Boy is powered by a double expansion steam engine system? High pressure exhaust steam from the smaller diameter forward cylinders becomes the steam supply for the larger diameter low pressure cylinders at the rear. 
Poor efficiency is what killed the steam locomotive as rejection losses in the form of low-grade energy from the exhaust of the low-pressure cylinder could not be recovered. A lot of energy goes out with the uncondensed steam to the tune of 970 btu per pound. 

Rumor has it that Generous Motors (GM) came to the rail transport industry and told them to use our diesel electric locomotives to ship our cars to customers and coal to our factory power plants or we will find rail transport companies that will. 

 

[Dave Crevie]

Probably as good an explanation as I've seen, helped by it's being centered on one specific locomotive. I'm surprised there is still interest in this.

[Bill Seitz]

Any open loop system like this has a huge loss of efficiency. Had it been feasible to recycle the steam in a closed loop system, the efficiency would have climbed considerably as is the case with steam electric power generators. The main issue with the steam locomotives was the huge number of moving parts and the enormous amount of maintenance. Diesel-electrics are much simpler. As for efficiency, internal combustion engines are also very inefficient, because they're again open-loop and throw away an enormous amount of their fuel-burning energy into the surrounding environment as heat - around 80%. The gain is in the electric drive which is far simpler. Carbon dioxide is touted as the reason for climate change, but the enormous expulsion of heat from both fuel burning and electric machines is a large, unaccounted cause.

 

Electric inter-urban railways/streetcars were common in larger metropolitan areas prior to WWII. After the war, principally GM bought up many of these electric inter-urban rail systems and replaced them with diesel-powered buses. They also influenced communities with lucrative deals to buy buses to compete with rail systems. Now after decades of environmental damage from diesel transportation, we're inspired to return to electric transportation which we once had and discarded, and at a huge cost to recreate.

[NSwanberg]

As for efficiency, internal combustion engines are also very inefficient, because they're again open-loop and throw away an enormous amount of their fuel-burning energy into the surrounding environment as heat - around 80%. 

 

Another energy loss issue I do not see much discussion about is the thermal-hydro energy lost from cooling tower evaporation both for power generation steam turbine condensers and air conditioning systems. 

 

Does pumping all the moisture into the atmosphere reduce natural evaporation elsewhere on our planet? 

 

If you ever had the pleasure of cleaning a large cooling tower, you know they are huge air cleaners. How does removing all that particulate matter from the air affect global warming? 

 

My head hurts... again. 

[Dave Crevie]

A lot of experimentation in design of steam locos occurred in the late 1920s on through the second World War. Most of this centered around condensing steam locomotives, and mostly by the Pennsylvania Railroad. They came a long way using both condensing boiler designs in combination with steam turbines to power the wheels.

 

The article below is from Wikipedia, ( and I don't always agree with their info), and although relates British experiments into condensing locos, still covers the theory pretty well.

 

Still, it was the diesel that brought the end of the steam locomotive. Cheaper to buy, cheaper to run, and did less damage to trackwork. 

 

 Condensing_steam_locomotive.pdf   277.52KB   10 downloads

[Bill Seitz]

Big Boy illustrates a common method with later articulated locomotives where waste steam from one set of piston drivers was routed to the second set, and attempt to increase efficiency. The Big Boys (think there were 16 built) are late '30s/early '40s technology, about the last of the steam locomotives built, though USG had narrow gauge locomotives built into the '50s (mostly some arrangement with eight drive wheels). The Big Boy is an amazing piece of work, and UPRR has several videos documenting the restoration and maintenance.

 

When UPRR's Big Boy 4014travels on excursions, it takes along a whole maintenance crew and equipment to maintain it. The crews spend a large part of the overnight stop hours performing maintenance in prep for the next day's run. In their heyday, it was an enormous maintenance task keeping fleets of steam locomotives operating, but what glorious machines and marvelous engineering and mechanical works they are.

 

I think the geared variety used most by the lumber/logging industry were likely the first all-wheel drive vehicles on the planet.

[Dave Crevie]

The Big Boy is a single expansion locomotive. Steam goes to all four cylinders at relatively the same pressure. A compound mallet has high and low pressure cylinders, where the high pressure steam from the boiler goes through the throttle valve to the cylinders on the rear engine, then is directed as exhaust to the low pressure cylinders on the front engine. On a simple expansion articulated, the steam goes through a common throttle valve to all four cylinders. This article may help to un-muddy all this. 

 

https://www.wikiwand...llet_locomotive

 

To me the logging and mining geared locomotives are the most interesting of all. That is why I mostly model logging railroads.  

 

Here ya go, Bill. Just for you. Some of the most interesting locomotives running through some of the most awe inspiring scenery in America. God bless this country!

 

https://youtu.be/CUl...Ph6wUXKEstlwqyA