What brought about the end of the steam locomotives?

The electrical guts of today's diesel locomotives evolved from streetcars. Streetcars roll on rails and use a metal stick to get their electricity from wires overhead. The electricity turns electric motors which turn the wheels. When was the last time you had to service the electric motor in your hair dryer, microwave, washing machine, refrigerator ... ? Pretty durable, eh?

Modern diesel locomotives are just electric locomotives which carry their own generating plant.

Diesel locomotive diagram: diesel motor powers generator. Electricity powers traction motors.

Diesel-electric locomotive history:
 Modern diesel electric passenger locomotive controls

These are the controls of an 1980s era diesel passenger locomotive. Using the forward/reverse lever, the throttle, and the train and engine brakes almost anyone could probably run this thing successfully - until they reached the first downhill stretch and the curve that followed. Electric buttons and switches start it up and shut it down - some old steam engineers hated diesels, saying they had all the personality of a bus. They said a diesel locomotive engineer was nothing more than a bus driver.

This is what they had been running until 1960:

CNR 6218 steam locomotive cab interior


Place your thumb over the right edge of the photo (to block out the throttle, brakes and reverser). That's how much more they needed to know to run a steam locomotive. This coal burner was built in 1942. Two quick points before you run it:
Diagram: Steam locomotive simplified

Like the diesel and your car, the steam locomotive uses an expanding, heated gas to do work. The gas in the pistons is steam. As the piston moves, it pushes steel rods which turn the wheels. There is a similar piston on the other side. Valves above the piston help the process by sliding back and forth, and they also help make the most efficient use of the steam.

Now, this is not that wimpy white condensation that comes from a kettle boiling at 212 degrees F.

This high pressure invisible superheated gas goes into the pistons at about 500 degrees F and is exhausted by them with a "chuff" as waste at about 225 degrees F.  

This is called an EXTERNAL combustion engine because the fuel is burned outside the engine. But which fuel?

British Thermal Units of heat produced per pound of fuel burned:
The first little Canadian steam locomotives burned wood. However, by the time the CPR was finished, it made sense to set up a system to move coal around the country to efficiently fuel the locomotives. Who wanted to chop, season and handle all that wood anyway?

Late in the steam era in Canada, oil was used to fire some steam locomotives. Oil is generally uniform in quality and easy to handle. Most of the large steam locomotives operating today for historical reasons burn oil because of this ease of handling..

Coal
Composition of Bituminous Coal (approximate)
Coal burning steam locomotive: firebox door

On a toasty July day, you are looking into the firebox of a Scottish-built locomotive used during the construction of the CPR. Each summer it runs tourist excursions out of Winnipeg. Like a fireman, you can work out the temperature of the fire in degrees Fahrenheit by its colour:
Below, we are trundling along behind a coal burning CPR locomotive which was running on a tourist railway in New Brunswick in 1988. The engineer is watching for traffic at the level crossing ahead. The steam you see is coming from the steam whistle as it sounds a warning for the crossing. There is lots of black smoke at this point because the fireman is putting coal into the firebox. Unburned black coal dust is being sucked right up the stack, volatile liquids from the new cold coal are smoking rather than burning completely, and the whole fire is burning less efficiently because the open firebox door is cooling it. Other pictures show the stack being perfectly clear.

Coal burning steam locomotive. CPR 29

You are getting a good view of the back of the tender. This is a fuel and water car that is semi-permanently connected to the locomotive. The front part of the tender carries the fuel. In this case, the coal is being manually shovelled from this car into the firebox of the locomotive. Large road engines might require 12 tons of coal to complete a trip. Larger engines used augers and compressed air to mechanically "throw" the coal into the fire. Behind and under the fuel in the tender is the water. Working hard, a large steam locomotive could evaporate 15,000 gallons of water during a run - this is a very rough estimate.

This heavy use of water use also drives up our steam locomotive operating costs. In Glenboro Manitoba in 1991, an old CPR wooden water tank is being used to hold the municipal water supply.

Glenboro water tank for use with steam locomotives

Identical and similar water tanks were built all across Canada. The water is in the top portion and the bottom third contains equipment and work space. A pump was used to get the water high enough for the fireman to quickly pour 5000-10,000 gallons into the locomotive tender (the large spout is missing from this tank). In winter, the tanks were heated to avoid making the world's biggest ice cube. A worker was needed to maintain and operate both the pump and the heater. The ball on the staff at the top is connected to a float inside the tank and shows how much water there is in the tank. In the 1940s there were 12 places between White River and Fort William (Thunder Bay) where steam locomotives could take on water.

Why did they need 12 places to get water on 250 miles of railway? If you are delayed, run short of water and allow the boiler area above the firebox to boil dry, you will get that explosion mentioned earlier. To avoid this explosion you could "drop the fire" onto the track and block the main line as you waited to be rescued. You would avoid the explosion, but your actions would be reviewed by railway officials and perhaps result in discipline.

Below, is a diagram of a firebox and boiler. The crew would be inside a cab (not drawn) at the left end (you can see the thin firebox door set into the left end below the letter d). The front of the locomotive would be farther to the right.

The layers of the coal fire are at the lower left, with the main combustion taking place at a . The gases (including methane) swirl around a brick arch as they burn, until they get to the exhaust flues at i and b . The firebox and flue assembly is jacketed with water to maximize heat conduction to the boiler water. The top surface of the water in the boiler is just covering the firebox. You can see that you would want to have a little extra water in the boiler if you were going down a hill (i.e. with the right side of the diagram tilted down). This would prevent the steel "crownsheet" of the firebox from becoming uncovered. Above the surface of the water, steam is represented by white puffy clouds. By opening the throttle at the left d , dry steam from the steam dome at the top right would be piped to the pistons to move the locomotive.

Diagram: steam locomotive firebox (a), coal burning on grates, exhaust gases entering flues (i, b), throttle (e), throttle lever (d)

When this was the best technology available, it made sense to:
  • Bring in coal from Pennsylvania by lake freighter to a special CPR coal dock at Jackfish, just east of Schreiber
  • Transport coal by rail over the 555 mile division and load it into the coaling towers at the 125 mile crew change points (there was also a tower at Jackfish)
  • Maintain water tanks every 20 miles or so with their own workers to operate the water pump and heater
  • Pay a fireman on each locomotive to keep the fire and water hot, and to take on more coal and water en route
  • Take a locomotive apart and rebuild the boiler every 5 years when its government safety permit expired
  • Keep idle locomotives hot overnight with banked coal fires so they wouldn't freeze or take hours to reheat and resteam for service
  • Maintain large shop forces to clean out fires, wash out boilers, maintain driving rod and wheel bearings, repair points where steam was leaking, and keep the engines clean and shiny by removing all the soot, coal dust, oil, water impurity stains and assorted grime which resulted from the locomotives' messy eating habits
  • Maintain helper steam locomotives at long grades because the engines of many trains did not have the ability to drag a heavy load up a long hill by themselves
  • Accept that only 7% of the fuel was actually used to pull the train
CPR steam locomotive 5319. photo: 1932
Locomotive 5319 was built in 1921 and was typical of Schreiber freight locomotives.
This photo is at West Toronto in 1932.

CPR steam locomotive 921. Photo: 1932
Locomotive 921 was built in 1912.
This type of locomotive moved cars locally and worked as a helper engine around Schreiber into the 1950s.
It is standing by a wooden coaling tower at Ottawa in 1932.

Steam locomotive maintenance: steam superheater tube replacement
You are looking into the front of a locomotive during an overhaul. The circular passages are the flue pipes which carry the coal exhaust gases through the boiler and out the smoke stack above worker's head. The pipes they are inserting are "superheater pipes" which loop some steam back WITHIN the flues to scavenge more heat from the exhaust gases. If you REALLY CARE, you can see superheater loops in the firebox diagram above to the right of the points marked "i".

But wouldn't you rather have a diesel?
(1950 advertisement)

Alco advertising for diesel electric locomotives

  • The Schreiber Division was one of the first sections of the CPR to dieselize in the early 1950s. 
  • Two diesel locomotives connected together by wires and air hoses were operated by one engineer and they could pull twice as much as the steam locomotive 5319 above. They didn't need helpers like locomotive 921 on steep grades because the diesels' electric motors and smaller power wheels were perfect for this kind of work.
  • If you count two diesels connected together as one locomotive, on the Schreiber Division:
    • 77 steam locomotives were replaced by 38 diesel locomotives
  • On through trains, the diesels probably ran over the entire 555 mile division (Sudbury/Cartier to Fort William) without stopping for fuel. None of the trackside water tanks between crew change points would have been needed.  
  • Instead of coal from Pennsylvania, the new locomotives burned diesel fuel which was much easier to ship and handle than dusty bulky coal.
  • And of course, the diesels used 25% of the fuel energy for moving freight, compared to only 7% for the steam locomotives.

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