Tuesday, February 17, 2015

The Secret Science of Sleet Scraping, Part II - Pantographs

David writes......

In Randall's original article on sleet scraping for third rail and trolley pole electric railway properties, a commenter asked about pantographs.

I've read that the Pennsylvania Railroad normally operated with the rear pantograph up. During sleet storms and other conditions where the overhead could ice over, the front pantograph would be raised, but cut out from the electrical system, so it could knock off ice on the wire before the rear, power-collecting pantograph came into contact. Above, here is a photo from Marty Bernard showing both pans up on a GG1 at Potomac Yard, near Washington, D.C.
This also appears to have been the case for the South Shore, though some older photos show cars in good weather condition running with the front pantographs up, while others show the rear pantographs up.  Could one of our readers enlighten us?

In the photo above, we see a standard St. Louis light rail car. Note the pantograph in the front, just behind the headlight. This is a sleet scraping pantograph. These sleet cutters appear on some Siemens light rail cars . They were developed by the late Fred Perry when he served as a consultant for the Metrolink system in St. Louis. Of course, Fred was a friend of IRM and many other traction museums until his untimely death about ten years ago. St. Louis, as I well know from living there for nine years, gets a lot of ice storms compared to other parts of the country. Such storms create havoc on the streets and the transit systems. Fred directed the installation of a spare pantograph on the front of one of the Metrolink cars. The pantograph was not wired to collect power, but was wired into a resistor, which in turn would head the collector blades on the top of the pantograph. The front pantograph was also apparently tuned to place more pressure on the overhead. The end result was a heated sleet scraper that would clear the overhead before the power-collecting pantograph came into contact with the wire.

According to Fred, when he told me this story at the Museum of Transportation years ago, the Siemens engineers were horrified at first when they heard that this modification had been made. After they inspected it up close, it became an optional feature on some of their light rail cars. I know some of the cars used by the Utah Transit Authority here in Salt Lake have the same sleet scraping pantograph. In the photo above, we see a similar setup. I've noticed that not all of the UTA cars have these. Having lived here for about 18 months, I can say we don't seem to get as many ice storms as I experienced in St. Louis.

So folks, there you have it! The complete science of sleet scraping!

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