Steam Engine – Mechanical Design
Presented by the Retro Resurrections Team:
Brian Mohr bjm210@psu.edu; Kevin Moore ktm114@psu.edu;
Chris Rossi cgr111@psu.edu; Joe
Snyder jcs259@psu.edu
Sponsored by Penn State’s Mechanical Engineering Dept.
Technical Contact and Faculty Coach:
John Lamancusa jsl3@psu.edu
Contents
of the Webpage:
Executive Summary
Our objective for this project was to re-create the steam engine that was commissioned by Louis Reber and designed and built by students between 1890 and 1891. There is only one photograph that remains of the steam engine, and no part prints so, we were forced to reverse engineer the engine from the photograph. Unlike the original steam engine though, this engine will be powered by compressed air, as opposed to being powered by steam. Below is one of the six working scaled steam engines designed and built by Retro Ressurections.
Technical Approach
The technical approach that we was used was to identify and sketch all parts, produce part prints from the sketches, and produce a prototype (a working scale model) from the prints. Below you will find the design specifications, alternative designs, and the manufacturing process plan.
Background: The steam engine was commissioned by Louis Reber and designed and built by students between 1890 and 1891. The steam engine was a featured attraction in the department for many years, but at some point, it disappeared without a trace.
Design Specifications:
The only dimensions (full scale) given in the thesis are as follows:
· Diameter of the cylinder 6”
· Diameter of the piston rod 1.6”
· Diameter of the fly wheel 36”
· Stroke of piston 8”
These design dimensions were found in Patee Library by the ME 414 steam engine group. All the rest of the dimensions have to been scaled from the original photograph above.
Alternatives Considered / Justification:
Most of the design work was being performed with the goal of reproducing the original steam engine. One choice that was available was the valve design.
One of the most important parts of a steam engine is the valve design. Since the valve design is not clearly evident in the photograph, some interpretation was required. Only the inlet and exit ports are shown in the photo. With this information two basic designs were considered and one was thrown out because of its complexity, and the fact that it didn’t resemble that of the construction from the one in the photograph. We ended up using the cylindrical slide valve shown below.
Cylindrical Slide Valve
Here’s an explanation of how the valve works: 1) Steam enters through the valve and expands, causing the piston to move 2) As the piston moves, it pushes out the used steam 3)
When
the piston reaches the other end, the cycle restarts.
The cylindrical slide valve
design was very popular and widely used at that the time period of the original
steam engine. It looks like this was
probably the design that the one in the photograph used.
Manufacturing Process Plan:
Casting:
The flywheel (aluminum) of the steam engine was the only part cast. Rapid prototypes of the flywheel were made using the LOM. The prototypes were then mounted to a board and used as casting patterns. The volume of the flywheel was calculated to determine the amount of metal needed for each mold. Post casting touch up work to be preformed on the metal lathe and mill. Below is a picture of two recently cast flywheels.
Machining:
The remaining engine parts were hand machined in the Learning Factory. Items milled were: slider housing, valve housing, bearing housings, crank arm, eccentric arm, and the cylinder shroud. Items turned on the lathe were: slider, valve, main axle, crank arm wheel, cylinder, cylinder housing, cylinder caps, and the eccentric cam.
Engineering Drawings
Below is the fully assembled AutoCad drawing of the Steam Engine Prototype
Steam Links
Below are some links that we found helpful in the research of our steam engine.
http://www.steammodels.com/how_works.htm
http://home.earthlink.net/~dlaw70/sep.htm scroll down to
see pictures of a model steam engine
http://www.traverse.net/members/remy/pages/steam.html#how%20steam%20engine%20work
click on the drawings for an animated view of how a steam engine
works (most useful site)
Last revised: April 17, 2002