O-Gauge Steamer
NAXJA Forum User
- Location
- Colorado Springs, Colorado
OK! Steam Engines! Wait, what is my screen name? O-Gauge Steamer?
There is a funny thing that happens with a steam engine. Something that only an electric motor comes close to reproducing but with a significant difference.
A internal combustion engine builds torque as the engine speed increases. Load the engine too early and it stalls. This we all know and accept as normal. Rather silly if you think about it...
An electric motor can develop it's maximum torque at a very low speed but will stall out also if the load exceeds the torque available. This also we all know and accept.
Then we come to steam engines that are not only perfectly capable of supplying maximum torque at zero rpm but it will not "stall" either.
Do not confuse a lack of mechanism movement with a stall.
In the early days of steam, more than on engine destroyed itself due to the inattention of the operator. If the driven mechanism is bound, incapable of translating the reciprocating motion to rotary motion, then what usually happens is that the connecting rod from the piston to the flywheel turns into a pretzel.
For example:
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What happened here, as you can barely read... Is that the engine "came to a grinding halt" obviously, the Engineer did not get the steam cut off soon enough.
Then, there is this nice example of the power of steam:
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Ah yes, the mechanism was bound and the engine continued to supply power. This is, actually the largest drawback to steam power. It has no built in safeties. Whereas, both internal combustion and electric will stall out protecting themselves, a steam engine is perfectly happy to rampage about destroying everything it can.
And you wonder why I like them...
At the end of Big Steam (the era I model) Locomotives were utilizing a concept called "super heating". The steam collected in the steam dome atop the boiler was first routed through the exhaust gasses before being delivered to the working cylinders.
Consider this. The working pressure of the end of life boilers was 350psi. Now, those of you out there that are Science Geeks can grasp just how bloody hot the water had to be in order for it to vapourize at that pressure. Then, you run it through the exhaust heating it up even more. Then you release it into the cylinders where it expands.
A steam engine has two basic controls. The Throttle Lever and the Johnson Bar. The throttle is understandable the Johnson Bar on the other hand... The Johnson Bar selects the direction in which the engine turns the wheels plus neutral. The most efficient way to operate a steam locomotive has the Engineer place the Bar in a portion of the travel called the "cut off". What is happening is that the timing is being altered to cut off the steam early allowing it to work by expansion instead of just by pressure. Each Company (i.e. Union Pacific etal) had a spot in the travel of the Bar that Engineers derisively called "The Company Notch". Engineers at the corporate level ran some numbers and decided that that location gave the best performance whilst minimizing the steam usage. Most Locomotive Engineer disregarded this and ran the engine as conditions warranted.
It was a matter of fuel economy. The steam is obviously lost and water has to be pumped back into the boiler. Use too much water and the train stops early. Bad to delivery times, bad for the bottom line. Engineers that blatantly did this were fired. Union notwithstanding.
In the end, it was the incredible maintenance costs as well as the labour costs that killed the steam engine.
As for what they were, here is a brief description of the largest engine ever built. Teh Union Pacific Big Boy.
"During the late 1930s, the Union Pacific often used helpers to move trains from Ogden to Wahsatch. The UP wanted to simplify this move so they asked their "Department of Research and Mechanical Standards" (DoRMS) to design a locomotive that could pull a 3600 ton train unassisted over the 1.14% grade of the Wahsatch.
The designers determined that to pull a 3600 ton train, a tractive effort of 135,000 lbs would be needed. Assuming a factor of adhesion of 4.0, the weight on drivers would have to be 4.0 * 135,000 = 540,000 lbs. Given an axle loading of 67,500 lbs each, this would require 8 drivers or an x-8-8-x wheel arrangement. The designers agreed upon the 4-8-8-4 design. Next, the horsepower and cylinder sizes were computed based on 300 psi boiler pressure. Although they weren't planning to pull these freight trains at 80 MPH, the DoRMS designed them for 80 MPH in order to have a sufficient factor of safety built into the design. What resulted is considered by many to be the most successful articulated steam locomotive ever built. 4000 was delivered to Omaha at 6PM, September 5, 1941.
The 25 Big Boys were built in two groups. The first group, called "class 1", were built starting in 1941. They were numbered 4000-4019. The second group, "class 2", were built in 1944. They were numbered 4020-4024. The last revenue freight pulled by a Big Boy was in July of 1959. Most were retired in 1961. The last one was retired in July of 1962. As late as September, 1962, there were still four operational Big Boys at Green River, WY.
The total mileage of each of the Big Boys from class 1 were roughly the same -- 1,000,000 miles. 4016 had the lowest mileage -- 1,016,124. 4006 had the highest mileage -- 1,064,625. Of the second group, 4024 had the highest mileage -- 811,956.
Firebox heating surface included 111 sq ft (10.3 sq m) in seven inverted-T shape circulators and a combustion chamber extending 9 ft 3 in (2.8 m) forward of the ashpan. One of the heaviest engines in the world, the 25 "Big Boys" were the largest steam engines ever built for regular service. The last five delivered in 1944 were fitted with Type A superheaters.
The Big Boys carried almost 70,000 lb (31,752 kg) more on its relatively tall drivers than did any other engine of comparable driver size. (The DM&IR's M3 2-8-8-4 engines -- Locobase 2405 -- had a higher weight on drivers, but had 63-inch/1,600 mm drivers.) Each one cost $265,000 when delivered.
These engines could maintain 70 mph (113 km/h) and rode quite steadily (The four pistons evacuated 22,700 cu ft/642.8 cu m of steam per minute at that speed.)"
And yes, I have one of these monsters on the rails in my basement along with it's "baby brother "The Challenger" which is a 4-6-6-4 wheel combination. My 1/48 scale electric model weighs in at 25 pounds.
The real deal tipped the scales at 772250 lbs with a tender weighing in at 436500 lbs for a combined "curb weight" of 1208750 lbs.
That is better than 600 tons boys...
There is exactly one of these left that can be fired. There was a plan to get it back on the road until it was realized that modern rails can not take the weight.
There is a funny thing that happens with a steam engine. Something that only an electric motor comes close to reproducing but with a significant difference.
A internal combustion engine builds torque as the engine speed increases. Load the engine too early and it stalls. This we all know and accept as normal. Rather silly if you think about it...
An electric motor can develop it's maximum torque at a very low speed but will stall out also if the load exceeds the torque available. This also we all know and accept.
Then we come to steam engines that are not only perfectly capable of supplying maximum torque at zero rpm but it will not "stall" either.
Do not confuse a lack of mechanism movement with a stall.
In the early days of steam, more than on engine destroyed itself due to the inattention of the operator. If the driven mechanism is bound, incapable of translating the reciprocating motion to rotary motion, then what usually happens is that the connecting rod from the piston to the flywheel turns into a pretzel.
For example:
What happened here, as you can barely read... Is that the engine "came to a grinding halt" obviously, the Engineer did not get the steam cut off soon enough.
Then, there is this nice example of the power of steam:
Ah yes, the mechanism was bound and the engine continued to supply power. This is, actually the largest drawback to steam power. It has no built in safeties. Whereas, both internal combustion and electric will stall out protecting themselves, a steam engine is perfectly happy to rampage about destroying everything it can.
And you wonder why I like them...
At the end of Big Steam (the era I model) Locomotives were utilizing a concept called "super heating". The steam collected in the steam dome atop the boiler was first routed through the exhaust gasses before being delivered to the working cylinders.
Consider this. The working pressure of the end of life boilers was 350psi. Now, those of you out there that are Science Geeks can grasp just how bloody hot the water had to be in order for it to vapourize at that pressure. Then, you run it through the exhaust heating it up even more. Then you release it into the cylinders where it expands.
A steam engine has two basic controls. The Throttle Lever and the Johnson Bar. The throttle is understandable the Johnson Bar on the other hand... The Johnson Bar selects the direction in which the engine turns the wheels plus neutral. The most efficient way to operate a steam locomotive has the Engineer place the Bar in a portion of the travel called the "cut off". What is happening is that the timing is being altered to cut off the steam early allowing it to work by expansion instead of just by pressure. Each Company (i.e. Union Pacific etal) had a spot in the travel of the Bar that Engineers derisively called "The Company Notch". Engineers at the corporate level ran some numbers and decided that that location gave the best performance whilst minimizing the steam usage. Most Locomotive Engineer disregarded this and ran the engine as conditions warranted.
It was a matter of fuel economy. The steam is obviously lost and water has to be pumped back into the boiler. Use too much water and the train stops early. Bad to delivery times, bad for the bottom line. Engineers that blatantly did this were fired. Union notwithstanding.
In the end, it was the incredible maintenance costs as well as the labour costs that killed the steam engine.
As for what they were, here is a brief description of the largest engine ever built. Teh Union Pacific Big Boy.
"During the late 1930s, the Union Pacific often used helpers to move trains from Ogden to Wahsatch. The UP wanted to simplify this move so they asked their "Department of Research and Mechanical Standards" (DoRMS) to design a locomotive that could pull a 3600 ton train unassisted over the 1.14% grade of the Wahsatch.
The designers determined that to pull a 3600 ton train, a tractive effort of 135,000 lbs would be needed. Assuming a factor of adhesion of 4.0, the weight on drivers would have to be 4.0 * 135,000 = 540,000 lbs. Given an axle loading of 67,500 lbs each, this would require 8 drivers or an x-8-8-x wheel arrangement. The designers agreed upon the 4-8-8-4 design. Next, the horsepower and cylinder sizes were computed based on 300 psi boiler pressure. Although they weren't planning to pull these freight trains at 80 MPH, the DoRMS designed them for 80 MPH in order to have a sufficient factor of safety built into the design. What resulted is considered by many to be the most successful articulated steam locomotive ever built. 4000 was delivered to Omaha at 6PM, September 5, 1941.
The 25 Big Boys were built in two groups. The first group, called "class 1", were built starting in 1941. They were numbered 4000-4019. The second group, "class 2", were built in 1944. They were numbered 4020-4024. The last revenue freight pulled by a Big Boy was in July of 1959. Most were retired in 1961. The last one was retired in July of 1962. As late as September, 1962, there were still four operational Big Boys at Green River, WY.
The total mileage of each of the Big Boys from class 1 were roughly the same -- 1,000,000 miles. 4016 had the lowest mileage -- 1,016,124. 4006 had the highest mileage -- 1,064,625. Of the second group, 4024 had the highest mileage -- 811,956.
Firebox heating surface included 111 sq ft (10.3 sq m) in seven inverted-T shape circulators and a combustion chamber extending 9 ft 3 in (2.8 m) forward of the ashpan. One of the heaviest engines in the world, the 25 "Big Boys" were the largest steam engines ever built for regular service. The last five delivered in 1944 were fitted with Type A superheaters.
The Big Boys carried almost 70,000 lb (31,752 kg) more on its relatively tall drivers than did any other engine of comparable driver size. (The DM&IR's M3 2-8-8-4 engines -- Locobase 2405 -- had a higher weight on drivers, but had 63-inch/1,600 mm drivers.) Each one cost $265,000 when delivered.
These engines could maintain 70 mph (113 km/h) and rode quite steadily (The four pistons evacuated 22,700 cu ft/642.8 cu m of steam per minute at that speed.)"
And yes, I have one of these monsters on the rails in my basement along with it's "baby brother "The Challenger" which is a 4-6-6-4 wheel combination. My 1/48 scale electric model weighs in at 25 pounds.
The real deal tipped the scales at 772250 lbs with a tender weighing in at 436500 lbs for a combined "curb weight" of 1208750 lbs.
That is better than 600 tons boys...
There is exactly one of these left that can be fired. There was a plan to get it back on the road until it was realized that modern rails can not take the weight.
