Alternative & Renewable Energy Blog

Last time, I described the design and construction of the cylinder and crankcase for the steam engine. This time, I'll be wrapping up the basic design with the cylinder head and cam drive. Without getting into too much detail (I may yet try to patent this thing), the valve alternately allows steam into the cylinder and vents it out again during the upstroke.

Combined with the cylinder exhaust ports, this configuration is referred to as a semi-uniflow engine. If I did not vent the upstroke and allowed it to recompress, which would maintain the temperature gradient of hotter at the top and lower at the bottom, then it would be a true uniflow engine.

I felt, however, that the loss of thermodynamic efficiency was acceptable if it reduced the risk of hydro-locking the engine (where a liquid, which is basically incompressible, enters the cylinder and stalls it with potentially damaging results). I would rather have it work with a high degree of reliability than be highly efficient, but prone to breakdowns.

The Cylinder Head

The cylinder head was the most difficult part of the engine to design, and went through multiple revisions until I was satisfied with the result. Yet the first design still failed miserably, which prompted further redesigns. All told, I spent at least a month just sketching different configurations before I came up with one robust enough to work (although it was much more difficult to machine). It would be another four months until I came up with a design that was both robust AND simple to make, but I will discuss that during a later installment.

The Cam Drive

The final part to build for the motor was the cam drive. Given my lack of money and the large number of abandoned bicycles on campus, I was able to repurpose two of the rear sprockets from a cannibalized 18-speed. As luck would have it, the largest and smallest sprockets on the rear wheel were a perfect 2:1 ratio. I made up some adapters to attach the two, cut an old chain to length, and finished assembling and timing the engine. (Note: I do not recommend doing this for a cam drive. It is insanely dangerous and WILL take a finger off if you get caught).

Amazingly, the motor ran under its own power on compressed air after only 15 minutes of fiddling. After testing it and making sure it worked, the next step was to build a test stand.

Follow this link to see the motor in action.

Its principles may buy the time needed to transition to a low carbon economy, which is why the Institution of Mechanical Engineers is a staunch promoter of mitigation, adaptation, and geo-engineering in the UK. Key recommendations in a recent report include carbon sequestration by artificial/mechanical trees, building-integrated photobioreactors for biofuel harvesting, and use of reflective building materials to reduce urban heat island effects. Can geo-engineering deliver the envisioned cost-effective energy and environmental benefits?

The preceding article is a "sneak peek" from Alternative & Renewable Energy, a newsletter from GlobalSpec. To stay up-to-date and informed on industry trends, products, and technologies, subscribe to Alternative & Renewable Energy today.

The next part of the project was to design a uniflow-style cylinder for the engine. This design bears many similarities to a two-stroke cylinder, especially in the sense that the exhaust port is machined into the cylinder wall itself. But I couldn't use a cylinder from a two-stroke engine for a variety of reasons. First, because I had no need for intake or transfer ports, a two-stroke cylinder would have been unnecessarily complicated for my purposes. Also, according to period steam literature I've read, the optimal exhaust timing for a uniflow engine is 15% above bottom dead center (BDC) of a piston's stroke.

Because of the radically different nature of internal combustion (IC) engine physics, the ports are much larger and open much earlier in the stroke than would be efficient for the project. Assuming that the piston skirt covers the port when at top dead center (TDC) to prevent excess steam in the crankcase, the only consideration is maximizing the size of the port while maintaining the exhaust timing. In the case of this engine, I was able to machine four ports with a 6-mm diameter into the cylinder.

Of course, the only option was to once again make the parts myself. Cast iron is still the gold standard for cylinder liners, so I attempted to find a source. (I know I'll receive comments telling me all about coated aluminum liners, but bear with me - I'm a college student with basically no budget.). A funny thing about Denmark, though, is there aren't a whole lot of cast iron pipes lying around. I even tried going to the on-campus foundry, but they required me to make my own molds, specify the exact alloy desired (I had no idea), and wait for them to actually perform the production run.

Instead, I decided to use a piece of carbon steel, machine it myself, and have it honed by the campus shop since it was a prototype and longevity wasn't an issue at that point. For future designs, I would prefer something less prone to oxidation, such as a Nikasil lining or stainless steel. After machining the liner, I shrank-fit it into an aluminum cylinder to reduce the weight and provide a place to run the mounting studs through. In my next blog entry, I will describe the creation of the cylinder head and timing chain.

In my last blog entry, I described several design upgrades that could improve the efficiency of uniflow engines. The next step of my project was to build a functioning prototype and test its efficiency in a real-world setting.

One of the advantages of my proposed uniflow design is that most of the moving parts can be made with used parts from an internal combustion engine. The standard timing belt/chain ratio of 2:1 can also be used. Adding to my challenge, however, was the fact that I was participating in a study-abroad program through school and living in Denmark when I began the design process.

Normally, when I'm home in upstate New York, there are 3 or 4 separate junkyards that I can go to for wrecked motorcycle parts or scrap metal. But I had absolutely no knowledge of local junkyards or motorcycle shops in Copenhagen. Even if I did find one, I lacked a rapport with the owners that would give me access to crawling around the scrap heap.

After mulling over this problem for a few weeks, I stumbled upon an unlikely source of parts. It just so happened that the teaching assistants (TAs) for one of my classes also participated in the Shell Eco-marathon design project. This is an extremely impressive event where teams compete to build the ultimate high-efficiency car. The Danish team scored two first-place finishes in the hydrogen fuel cell and urban car events. (Unless this page changes, there is a picture of their team at this link.)

After offhandedly mentioning my problem, one of the TAs motioned me to check out their parts storage room. There, I unexpectedly became the proud owner of a pile of used Puch Maxi engine parts, including crankshafts, pistons, and main bearings, that the team no longer needed. My project had suddenly taken a flying leap forward. I was in business.

Because of the small size of the engine parts (50cc), I was able to repurpose a scrap piece of aluminum bar stock from the machine shop's storage room as the crankcase. I then heat-shrunk the two halves onto the crank bearings, used a cut-up piece of a Cheerios box as the oil gasket, secured everything with four 6-mm bolts, and installed the cylinder studs that I had scrounged from the leftovers of another student project.

Next time, I'll discuss the challenges I faced in trying to find cast iron pipe for a cylinder liner, as well as some of the calculations behind the design.

In recent years, cities have revitalized or installed streetcars and light-rail systems to stimulate economic and demographic growth. Not surprisingly, the public has taken to the idea in great numbers. During the 1970s and 1980s, some cities listened to commuter calls for an alternative way to get to work. San Diego was the first American city to build a modern light-rail system. Launched in the late 1970s, the California community's first line ran from San Diego to near the Mexican border and was immediately popular with the public.

Some twenty years later, Portland became the first American city to revive its electric streetcar service. In 2001, Oregon's most populous city built the first major, modern streetcar system in the United States for $57 million (USD). The investment has resulted in the creation of over 10,000 new residences and the investment of $3.5 billion within two blocks on either side of the streetcar lines. Today, other cities are studying Portland's success and seeking to copy it.

Older cities in Ohio are some of the communities that may follow in Portland's footsteps. In the early 1900s, Ohio claimed the largest network of trolley tracks in the United States. Now Cincinnati wants to return to those glory days. The New York Times reports that city officials are garnering financing for a $132 million streetcar system "that would connect the city's riverfront stadiums, downtown business district, and Uptown neighborhoods". The Times also reports that "at least 40 other cities are exploring streetcar plans to spur economic development, ease traffic congestion, and draw young professionals and empty-nest baby boomers back from the suburbs."

Cincinnati officials plan to pay for the proposed streetcar system with existing tax revenues and $30 million in private investment. Columbus, Ohio is also considering putting in a $103 million streetcar system from the Ohio State University campus to the downtown business district. It would be financed by a 4 percent surcharge on concert tickets, sporting events, and downtown parking, with an additional $12.5-million contribution from Ohio State University.

In recent years, many downtowns have begun to see their real estate values rebound. Consequently, streetcar and light-rail system promoted development extends back to the West Coast and to San Francisco and Sacramento. The continually- expanding Mission Bay Project in San Francisco offers streetcar line service to ferry service and exemplifies a fast-growing type of transit-oriented development. In environmentally-conscious California, streetcar use is also seen as a "green" alternative to driving a car.

Light-rail systems are also gaining popularity in many cities that once had streetcars. San Diego started this trend some 20 years ago, but it continues in many large to mid-sized cities today. Baltimore, Maryland; Charlotte, North Carolina; Houston, Texas; and St. Louis, Missouri all have new light-rail and streetcar systems which continue to attract passengers who are either moving back to downtown areas, or are tired of the long commutes and hassles of the freeway. In terms of environmental impact, urban planners confirm that a rail line uses only one-quarter of the land needed for a six-lane freeway

Conclusion

Tired of stalled commuter traffic and never-ending freeway congestion, the American public seems ready for a better way to get to work. In cities large and small, the traveling public is clamoring for new forms of mass-transit (such as light rail) and a return to the old technology of streetcars. Will the innovative designs, cost-effectiveness, and overall efficiency of electrically-powered streetcars bring them back to the streets of American cities?

Commuters once thought that the automobile was the only way to travel, in part because of America's interest in personal mobility. But is the electric streetcar the answer? It's interesting to note an article from the Saturday Evening Post in 1899. Though written during a time of great technological innovation, "The Trolley and it's Numerous Failings" excoriates the streetcar. "While the modern railroad has achieved almost perfection in its comforts and conveniences," the writer explains, "the modern trolleys distinctly fail in nearly everything in which it ought to be complete."

This piece in the Post concludes by arguing that the solution to the trolley problem in 1899 was the development of the automobile. Wouldn't it be ironic if a twenty-first century trolley now became the remedy for America's automobile problem? For some observers, such a reversal of fortune might be called "A Streetcar Named Progress".

Resources:

Driehaus, Bob. "Downtowns Across the U.S. See Streetcars in Their Future" New York

Times 14 Aug. 2008: A17

Previous Blog Entries in This Series

The American Streetcar (Part 1)

From Stagecoach to Streetcar (Part 2)

From Horse-Drawn Streetcars to Cable Cars (Part 3)

The Birth of the Electric Streetcar (Part 4)

Electric Streetcars and Trolley Technology (Part 5)

Electric Streetcars: Private Lines and Public Roads (Part 6)

The Rise of the Electric Streetcar (Part 7)

Electric Streetcars and the Industrial Revolution (Part 8)

General Electric and the Schenectady Streetcar (Part 9)

Streetcar Suburbs and Interurban Trolleys (Part 10)

Electric Amusement: The Trolley and Leisure (Part 11)

The Streetcar Turns a Corner (Part 12)

Electric Streetcars: The PCC and Wartime Mobility (Part 13)

Post-War Trauma for the Streetcar (Part 14)

The Long, Slow Near-Death of the American Streetcar (Part 15)