I've observed over the years that CTA rapid transit equipment has used gravity contact third-rail shoes. Do any other operations use similar shoes?
By "gravity contact", do you mean that there's no spring forcing the shoe onto the rail?
Also, I'm sure that most people are unaware that there are Summer and winter third rail shoes ( no, this is not like summer and winter air for your tires!). The New York City Transit Museum in Brooklyn has a display of the two types of shoes. The summer shoe contact plate is a solid casting, the winter shoe has two large oval holes in the contact plate. The docent explained that the holes minimize the buildup of ice and snow under the contact plate.
CTA third rail shoes are not spring loaded. There are also sleet breakers also attached to the third rail beam.
On the CTA do the shoes ride on top or the bottom of the contact rail?
Like the trolley poles and pantagraphs there are springs or air cylinders maintaining a positive upward force against the catenary wires. The third rail paddle shoes, such as "BART" maintain a positive downward pressure toward the top of the third rail with a torsion spring. https://s.hdnux.com/photos/45/17/01/9760864/3/gallery_medium.jpg
In areas Where there is sufficient ice build up on the third rail, the third rail can be suspended and the collector paddle is spring loaded in providing upward contact on the bottom of the third rail.
CSSHEGEWISCH I've observed over the years that CTA rapid transit equipment has used gravity contact third-rail shoes. Do any other operations use similar shoes?
there is a leaf spring damper of some type
According to https://www.google.com/books/edition/Electric_Railway_Journal/7ahMAAAAYAAJ?hl=en&gbpv=1&dq=Third+rail+gravity+shoe+pressure&pg=PA993&printsec=frontcover
at least 50 lbs of shoe weight is needed in gravity systems for them to work correctly...
CTA shoes, like those that were used on New York City's Elevated Railroads, both the IRT and BMT operated, press straight down on a relatively high and close third rail. This does not permit a cover board, but some safety can be provided by a vertical board several inches higher than the third rail agaist the outer side.
Except for Metro North's former New York Central electrtified lines, all other North american 3rd-rail electrifications use sprung padel shoes that contact the top of the third rail under a braketed protection cover board. MN's system also buses a padel shoe, but is sprung to press upward agaist the bottom of the third rail located directly under the protection board.
No example of the elevated type of electrification renmains in use in New York City.
Our community is FREE to join. To participate you must either login or register for an account.