This week’s post is from guest blogger Linda Bolla at the Erie Maritime Museum (title is mine, so don't blame her). Linda has written a number of posts for Trailheads and her photos of the US Brig Niagara and the museum have appeared frequently. Thank you, Linda! (If you’re looking for Trails of History activities this weekend and the rest of the month, you’ll find them in the February program listings.)
Many Pennsylvania Trails of History sites carry the responsibility of preserving historic structures. The Erie Maritime Museum lives in an important Erie harborfront building, the former Pennsylvania Electric Company (Penelec) Front Street Generating Station (in operation from 1917 until 1991). The task of maintaining the building’s original machinery poses unique challenges, especially when we rely on those machines to be fully safe and operational.
The Museum exhibits a General Electric steam turbine generator that only last year received an important update, the installation of carbon brushes [Linda wrote about the project in a previous guest post]. Similar carbon brushes are important to running the Museum’s 50-ton Cleveland Crane, which is used to lift cannon and other heavy artifacts. The crane is operated by direct current motors powered by a General Electric motor generator (MG) set located in the building’s basement. The early 20th-century MG set consists of a 50-horsepower alternating current induction motor driving a 35-kilowatt direct current generator. Current is conducted from the rotating parts of the generator and is transferred through a sliding electrical contact involving carbon brushes.
Cleveland Crane at Erie Maritime Museum
Docent Rich Hall, a retired GE design engineer, recognized that these brushes will eventually wear down. He alerted Site Administrator Walter Rybka to the need to obtain replacement brushes now, while there are still people who have the expertise to make and install them. Patents on the motor parts range from 1893 to 1911, and specifications for the brushes were not readily available. If the brushes were allowed to wear out, the crane would stop working and the equipment could be damaged, requiring expensive repair.
Patent information on the induction motor
Rich’s colleagues Gary Lozowski (Morgan Advanced Materials application engineer, Greenville, SC) and Steve Dewitt (lab technician) were happy to have an opportunity to inspect the vintage machine and make the necessary measurements to manufacture the correct brushes. Morgan manufactured the parts and donated them to the Museum, as they had done for the earlier GE steam turbine project.
Old brushes being removed (back), new brushes installed (front)
On October 14, 2014, local GE motor engineer Walter Konstanty and Rich Hall installed the new, correct carbon brushes. As they removed the decades-old, worn brushes, they realized that some of them were not quite of the correct design. The new brushes needed to be sanded here and there to fit and to make smooth contact. The brushes’ pressure against the commutator was also checked.
New brushes are sanded to ensure smooth contact
Studying the vintage motor generator set and replacing all brushes now has helped ensure the Erie Maritime Museum’s crane motor will run for years to come, keeping this vital piece of equipment operational.
Trailheads is a behind the scenes look at the historic sites and museums along Pennsylvania's Trails of History. For more information, visit http://www.patrailsofhistory.com/.
Please note that some staff and volunteers at PA Trails of History sites are wearing masks while indoors. Visitors are encouraged, though not required, to do so as well.
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