Here's all you ever wanted to know about 3rd (and 4th) rail systems and their shoes. No overhead though.
http://homepage.ntlworld.com/russelliott/3rd-4th.html
fredswainHere's all you ever wanted to know about 3rd (and 4th) rail systems and their shoes. No overhead though. http://homepage.ntlworld.com/russelliott/3rd-4th.html
Strictly British, though. Surprised to see several pictures of 150 # rail. I thought that was only found on HO railroads running on code 100!
C&NW, CA&E, MILW, CGW and IC fan
There's a prototype for everything!
150# third rail? Seems a bit of overkill, to me. Anyhoo, I wouldn't want to be a MOW worker around that unprotected stuff. The LIRR/PRR over-running rail, with a little cover board, is scary enough. I always felt comfortable with the NYC's wooden (and, later, plastic) covered under-running third rail.
Hays
BNSFwatcherThe LIRR/PRR over-running rail, with a little cover board, is scary enough. I always felt comfortable with the NYC's wooden (and, later, plastic) covered under-running third rail.
Hays; The first I understand from being around the CA&E when little (and no cover board - bikes gave off a 4th July spark show). But I've never seen a pic of the NYC set up. How is the 3rd rail supported?
The under-running third rail on Metro North is supported by brackets shaped like an inverted J. As an aside, most rapid transit systems that use an exposed third rail and don't have a cover board.
The cast?/forged? "inverted 'J's" are mounted on about every sixth (extended) tie and are insulated from the third rail, which is suspended from them. Between the "J"s, a 3-piece creosoted wooden cover was routed to fit over the top and sides of the rail. These pieces were nailed together. Sometimes, a mis-driven nail would get too close to the rail, resulting in a surprise to anyone that got too close to it, but 600v DC is only a tingle! The wooden covers were slowly replaced by moulded plastic caps (one piece), starting in the 1960s. Dunno if any wooden covers still exist. Prob'ly somewhere.
Falcon48daveklepper Interurbans: Key System or Sacramento Northern, both third rail and overhead were on the Bay Bridge. Someone else tell me who used what. I believe that the Key Sytem and SN both used 3rd rail on the Bay Bridge. SP's Interurban Electric Railway used catenary on the same tracks.
daveklepper Interurbans: Key System or Sacramento Northern, both third rail and overhead were on the Bay Bridge. Someone else tell me who used what.
I believe that the Key Sytem and SN both used 3rd rail on the Bay Bridge. SP's Interurban Electric Railway used catenary on the same tracks.
In his book Red Trains in the East Bay, Robert Ford wrote that the I.E. and the SN both used the 1200V overhead on the bridge and the Key System used 600V third rail. This was the least expensive way to power cars from all three lines. Other sources mentioned that the SN ran on the Key System's 600V overhead for the stretch between 40th & Shafter and the Bay Bridge.
- Erik
Most SN equipment could run on either 600 or 1200V DC. But the stretch of Key System 600V was too short to bother changing from 1200 to 600 and back (both requiring power off) so half speed barely visible lights were the answer for the short distance. The SN did use 600V on their third rail between Sacramento and Chico and under trolley wire in both Sacramento and Chico.
The Broad Street subway and PATCO in Philadelphia, Miami, Baltimore, LA Red Line, and all current New York City rapid transit lines of all types all use the standard LIRR-PRR-H&M (PATH) third rail or something very close to it with the same type of cover board. Don't remember about Phila. Market Street. Cleveland has no third rail, only overhead wire. Washington is a somewhat different profile but does use a coverboard. CTA does not.
Urban Legend? While working in GCT, I heard that some employees would drive nails into the top of the third rail covers. That would get the attention of anyone that stepped on the third rail cover (a "no-no"), but don't know if it is true. I, for one, always stepped over. My father told a story, much similar. They were building our first job, 300 Park Avenue, methinks, over the train rooms of GCT. Working at night on the sub-structure, they took a midnight lunch break. One of the workers invited a new guy to have a seat. He spread his handkerchief on a third-rail shoe of a 4300/4500 M. U. car, parked on an adjacent track. The "new guy" sat on it and had an 'electrifying' lunch. No one was hurt. Dunno if this was true. Before my time and my father lied a lot. When I lived in New Rochelle, some of my schoolmates would cross the New Haven tracks by climbing over the top of boxcars on an inconvenient stationary freight. Some of them didn't make it. 11,000 v. AC is quite unforgiving.
daveklepperMost SN equipment could run on either 600 or 1200V DC. But the stretch of Key System 600V was too short to bother changing from 1200 to 600 and back (both requiring power off) so half speed barely visible lights were the answer for the short distance. The SN did use 600V on their third rail between Sacramento and Chico and under trolley wire in both Sacramento and Chico.
Most of what i read about SN operation over the Key System trackage also said that it was too short of a trip to bother with the changeover. The SN cars were equipped with a field shunt to allow the cars to operate at more than half speed.
For what it's worth, the SN's overhead was energized at 1,300 or 1,500V at different times in its history.
I'm curious why the third rail uses shoes instead of a moving wheel. Isn't there resistance and heat to worry about by rubbing a shoe against a rail, or does a wheel just get gunky and not keep everything clean with friction?
aegrotatio I'm curious why the third rail uses shoes instead of a moving wheel. Isn't there resistance and heat to worry about by rubbing a shoe against a rail, or does a wheel just get gunky and not keep everything clean with friction?
By analogy, this would be similar to a trolley wheel vs. a trolley shoe. The resistance isn't that much of a factor and a shoe allows a bigger contact area against the third rail. Also, a wheel involves additional moving parts which would need to be lubricated.
Dunno, fur sure, me, but I never heard of New York Central's under-running third rail being lubricated. I think the disparity of the steel third rail and the copper-alloy pickup shoes kept the contact clean and even lubricated. The pickup shoes were easily replacable. I have heard of overhead trolley wire and catenary being lubricated, prob'ly with a graphite-based goop. Interesting to know: what would be the effect on a rolling wheel picking up juice? Seems to me that the lubricant wouldn't last long in the bearings, especially in Hi-V applications. With a wheel, of course, you would have to raise the under-running rail, or raise the protection board on an over-running system. Both would cause clearance problems.
I seem to recall hearing that trolley shoes were lubricated with graphite. I do remember reading that some pantographs were lubricated with graphite on their contact surfaces.
It would make sense to make the contact surface of a third rail shoe from a softer metal than the rail, that way the wear would be on the easily replaceable shoe. I would imagine that the wear was pretty light as the contact forces were low and the rail would have been polished by the passage of many shoes.
Trolley shoes are (they are still made and several operators use trolley poles instead of pantographs and so do trolley buses) have a graphit insert that is impregnated with metal (i prsume copper) which lubricates as it makes electrical contact. It is expected to wear out after about 10,000 miles (average overall speed of 10 mph inlcuding layups and stops gives 1000 hours or about every 40 days, in practice probably every two months). This prserves the life of the wire which is a lot more expensive to replace. Panographs have a similar replacable insert in the top surface of the "pan."
I posted my question before reading this month's Trains magazine where in the Ask Trains department they discuss the pantograph carbon strip. It makes more sense to make the pantograph/shoe wear away much faster before the more expensive catenary/third rail and I appreciated the insight.
In this same issue, Boston's MBTA has accepted delivery of new Blue Line trains. Left out of the announcement was the fact that the Blue Line uses both third rail *and* pantograph power collection. If you find yourself in Boston you must take a trip to check out the power changeover at Airport Station. The Blue Line modernization program to increase train length somehow does not change the third rail/pantograph configuration, which I find interesting to say the least.
Many years ago the change took place at Maverick Staiton, not the Airport Station. Anyone know why the change?
daveklepper Trolley shoes are (they are still made and several operators use trolley poles instead of pantographs and so do trolley buses) have a graphit insert that is impregnated with metal (i prsume copper) which lubricates as it makes electrical contact. It is expected to wear out after about 10,000 miles (average overall speed of 10 mph inlcuding layups and stops gives 1000 hours or about every 40 days, in practice probably every two months). This prserves the life of the wire which is a lot more expensive to replace. Panographs have a similar replacable insert in the top surface of the "pan."
Many interurbans (including the North Shore Line) used metal inserts on their trolley poles instead of carbon inserts. I'm not entirely sure of the reasons (carbon inserts were certainly available in North Shore's later years), but it probably had to do with the ability of the metal inserts to better withstand impacts on directly suspended trolley wire at high speed. As explanation, by "directly supended", I mean a simple overhead structure that consists of nothing but the contact wire between the supporting cross spans. There are no messenger wires over the contact wire to keep the wire level ("catenary")and, as such, the contact wire sags between the cross spans. The cross spans on directly suspended wire are relatively rigid spots on otherwise flexible overhead which create an impact at speed. All of the NSL's trackage in Wisconsin had directly suspended trolley wire, as did the Mundelein branch and most of the Shore Line Route. Most (but not all) other interurban lines also used this kind of overhead structure.
To lessen the mechanical friction on the wire from the metal shoes, NSL regularly lubricated its overhead wire with some concoction, which probably included graphite. When I was a youngster (I'm admitting how old I am), I remember several times seeing the 606 line car come through Libertyville (on the Mundelein branch) with a worker standing on the roof platform holding something against the trolley wire, probably the lubricating material (of course, this was before OSHA). I imagine this was common practice on properties where metal shoes were used.
The worst of all things on the trolley wire was a trolley wheel. That may seem counter-intuitive. After all, a wheel should provide less mechanical friction than any kind of sliding shoe. The problem is that the wheel provides a much smaller electrical contact surface than a shoe. The electrical arcing that results, particularly with equipment that draws a lot of power (like a NSL car), will wear the wire much more than mechanical friction from a shoe.
Among the transit systems that once used both overhead catenary and third rail on the same line I did not see listed the Pennsylvania-Reading Seashore Line's Camden to Millville line. Up until the late 1940's the PRSL used mu'ed cars, some of them wooden, on this line about 60 miles long. They used overhead catenary in the city of Camden, NJ and third rail out in the more open countryside. When they were told after the war to get rid of the old wooden cars the PRSL chose to get rid of the electric motors instead and go to steam or diesel hauled coaches. The route still exists as a freight only operation but in some places you can still see, faintly, where the old third rail was. Interestingly, light rail may soon return to this route as New Jersey Transit may extend its Trenton to Camden light rail southward to Glassboro and maybe beyond. Engineering studies are underway but most likely, like the present Trenton to Camden service, the vehicles will be diesel electric so neither catenary or third rail is likely to reappear on this route. Speaking of the safety of third rail, it never ceased to amaze me how much third rail existed in the streets of Long Island City, NY in the late 20th Century. The locals hopped, skipped and jumped over the rails as though they were nothing more than pedestrian speed bumps. That's gone now but I don't know if had to do with any accidents or safety concerns.
Re: LIC, NY -- I never heard of that before. Was it subway/el, LIRR/PRR, or trolley trackage? Didn't the Queensboro Bridge trolley use third-rail and trolley wire? Dunno, me. Anyone got any pictures? Very interesting.
Hays, who still doesn't know how to edit/condense previous comments before replying.
aegrotatio I posted my question before reading this month's Trains magazine where in the Ask Trains department they discuss the pantograph carbon strip. It makes more sense to make the pantograph/shoe wear away much faster before the more expensive catenary/third rail and I appreciated the insight. In this same issue, Boston's MBTA has accepted delivery of new Blue Line trains. Left out of the announcement was the fact that the Blue Line uses both third rail *and* pantograph power collection. If you find yourself in Boston you must take a trip to check out the power changeover at Airport Station. The Blue Line modernization program to increase train length somehow does not change the third rail/pantograph configuration, which I find interesting to say the least.
Boston's public transportation came under the "Public Control Act" of 1918. In 1947 it morphs into the "Metropolitan Transit Authority" (MTA) (Service Mark a "Circled T"). Expanding to cover all of eastern Massachusetts in 1964, it became the "Massachusetts Bay Transportation Authority". The MBTA now controls all Commuter Rail (reaching out 50 miles in each direction), Subways, and Local Bus Service.
Boston has 4 Subway Systems, Blue, Orange, Red, and Green lines. Orange and Red are 3rd rail subways, Blue under ground 3rd rail and surface pantograph, while the Green line is a "LRV" system. Today, all 4 lines come out of the ground and run on the surface, on old New Haven or Boston & Maine right of ways, in the suburbs.
Boston's "Blue Line" "Bowdoin" Street in downtown Boston to "Wonderland" station in Revere
In 1904 Boston's Blue line was built as the worlds first Subway Tunnel under a part of an Ocean, Boston Harbor, for Trolley use. It ran under Boston, Boston Harbor to Maverick Station. In (aprox) 1924 the old trolley line became a Rapid Transet subway line.
In 1952 the MBTA (then MTA) had a novel idear, they deceided to take over the Right of Way of the old Boston, Revere Beach, & Lynn narrow gauge commuter railroad and bring the subway out on the surface. Running near the salt water ocean, not wanting to fence the whole line, and subject to snow storms, they re-layed the line as standard gauge with overhead catenary wiring.
Don U. TCA 73-5735
It was the L.I. RR. They used the area for storage but there was a residential area nearby and people just walked over them like they were landscaping logs. I think if you go out to a satellite image, say Bing maps, you can see that much of the trackage in the yard is gone. I believe the intersection of 53rd Ave. and Vernon Blvd. was the area I am referring to. I think they have fenced off the area and the streets no longer cut through the yard
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