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Re: Trolley Poles and Pantographs
Author: fkrock
Date: 10-14-2015 - 09:16
The Doctor is correct. But tons of mis-information and idle speculation has been posted above.
In general pole operation came into use before pantographs were used in this country. Because equipment must be backwards compatible, new cars also used poles that are much cheaper and require less maintenance than pantographs.
Trolley wire can be set up for high speed trolley pole operation. For one example the Chicago, North Shore, and Milwaukee interurban line ran trains up to 80 mph using poles. Locally Sacramento Northern passenger cars that ran over 70 mph used poles while freight locomotives used pantographs.
In general locomotives with pantographs can draw more current from the wire than a trolley pole because they contact a larger wire area then provided by a trolley wheel or slider. A few interurban lines equipped their freight locomotives with two poles on each end required both poles to be on the wire for operation. Illinois Terminal wss one example.
Special trolley frogs designed for trolley poles were manufactured with small ramps on both sides that contact pantograph shoes and lower them below the frog. These were good only for low speed operation. Some operating companies put a second wire parallel with the regular wire about two inches lower to keep pantographs from snagging in trolley frogs.
In general pole operation came into use before pantographs were used in this country. Because equipment must be backwards compatible, new cars also used poles that are much cheaper and require less maintenance than pantographs.
Trolley wire can be set up for high speed trolley pole operation. For one example the Chicago, North Shore, and Milwaukee interurban line ran trains up to 80 mph using poles. Locally Sacramento Northern passenger cars that ran over 70 mph used poles while freight locomotives used pantographs.
In general locomotives with pantographs can draw more current from the wire than a trolley pole because they contact a larger wire area then provided by a trolley wheel or slider. A few interurban lines equipped their freight locomotives with two poles on each end required both poles to be on the wire for operation. Illinois Terminal wss one example.
Special trolley frogs designed for trolley poles were manufactured with small ramps on both sides that contact pantograph shoes and lower them below the frog. These were good only for low speed operation. Some operating companies put a second wire parallel with the regular wire about two inches lower to keep pantographs from snagging in trolley frogs.
