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| (1639414) | |
Linked Sets |
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Posted by GonzoUSN on Sun Feb 23 21:48:58 2025 Pardon my ignorance. I'm curious as to why the subway cars are linked into 4-5 car sets. Are there advantages to this? |
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Re: Linked Sets |
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Posted by Stephen Bauman on Sun Feb 23 22:32:49 2025, in response to Linked Sets, posted by GonzoUSN on Sun Feb 23 21:48:58 2025. I assume Mr. T. Dude will give a more complete explanation.As an outsider with engineering experience I see three advantages. First, there is commonality of equipment. An air compressor can handle two or more cars. This results in a weight savings. Second, multiple unit trainline signals are incorporated into the couplers. The coupler connections have proven to be troublesome. The linked cars eliminate the troublesome connectors. Third, elimination of cabs does provide more passenger space. I see many disadvantages. First, the coupler connection problem could have been resolved by using more modern (post 1900) signals for the trainlines. They did not have to incorporate the connectors in the couplers. They could have used cables with better connectors. They could have used optical or radio connections from the late 20th century. Second, the IRT patented a cab design that was available for passenger use when it wasn't used by a train operator. The BRT and the IND did not want to pay the IRT royalties to copy their or a similar design. Third, there's a lack of flexibility. The half train length sets means that many train lengths are either too long or too short for passenger loads most of the time. One workaround has been to alter service levels (train frequency). This creates a big problem with a trunk/branch system like NYC. The way to avoid merging conflicts is to operate balanced merges. The use of unbalanced merges results in delays at merge points. Fourth, there's a safety problem in case brakes have to be cut out in lead car. This means a tripper won't have any effect until a powered car tries to pass it. Trippers were originally placed sufficiently far from the impact point so that the train would stop should the second car tripper be actuated. That was 60 feet from the front tripper. Should the first 5 cars have their brakes cut out, that distance would now be 300 feet. They did compensate when the Archer Ave Subway was built. The diamond crossover was placed 300 feet from the terminal station entrance. The result was that a stub station with tail tracks that should have handled 40 tph could handle only 12 tph. Fifth, if a single car needs unscheduled maintenance, then 4 or 5 cars are out of service. This reduces availability or requires more spares. Spares are more costly because 4 or 5 cars cost more than a single car. |
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Re: Linked Sets |
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Posted by Andrew Saucci on Sun Feb 23 23:38:45 2025, in response to Re: Linked Sets, posted by Stephen Bauman on Sun Feb 23 22:32:49 2025. In addition, larger sets also allow for more articulation if desired."Second, the IRT patented a cab design that was available for passenger use when it wasn't used by a train operator. The BRT and the IND did not want to pay the IRT royalties to copy their or a similar design." Now that the IRT, BMT, and IND are all owned by the city, and unification happened a long time ago, is this patent still an issue? Apart from that, though, extra cabs require extra operators' equipment-- and that equipment is probably getting rather expensive. |
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Re: Linked Sets |
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Posted by Jackson Park B Train on Mon Feb 24 00:14:07 2025, in response to Re: Linked Sets, posted by Andrew Saucci on Sun Feb 23 23:38:45 2025. the patent is likely expired, but wasting cash on the computer/electrical control hardware especially in tiny cars like IRT, cTA, when ultra short trains are less common is silly. This BTW is one of my gripes with most LRV operations. Whether Portland, SF, LA, a single unit train is fairly rare, thus 2 cabs nose to nose waste both customer space and electronics investment. |
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Re: Linked Sets |
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Posted by LuchAAA on Mon Feb 24 01:23:40 2025, in response to Linked Sets, posted by GonzoUSN on Sun Feb 23 21:48:58 2025. There are definitely economic advantages.Parts and labor for sure. Maintenance. Fewer yard train operators should be needed too. Cuts and adds on 5 car units compared to single cars, or married pairs( 2 cars) should reduce labor and save money. A disadvantage is if one car on a 5 car unit(also referred to as a five car family) needs to be taken out of service, the other four cars do as well. |
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| (1639423) | |
Re: Linked Sets |
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Posted by Train Dude on Mon Feb 24 02:41:23 2025, in response to Re: Linked Sets, posted by Stephen Bauman on Sun Feb 23 22:32:49 2025. I think that you covered most of the highlights. I will add one positive and one not so positive. First the positive. Back before the R-68s were linked, the MDBF ran at about 100K Miles which was unaceptable. After the cars were linked, and the D-Train was running a trunkated service due to the closing of the Manhattan Bridge, the MDBF rose to over 500K miles on the Concourse R-68s. Once the bridge reopened the MDBF fell to between 200K & 250K which was still a vast improvement attributable largely to the removal of many troublesome components. At the same time, linking of the R-44s and R-46s while also improving reliability, masked the problem that if found before linking, might have negated the need for removal of the P-Wire braking and replacing the 2 air brake systems on those fleets. One other benefit was the saving of manpower. Inspections on 2-car linked units required a 6 man inspection team. But due to the removal of several components, a 4-car linked unit required 2 5-man teams. |
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| (1639424) | |
Re: Linked Sets |
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Posted by randyo on Mon Feb 24 03:43:47 2025, in response to Re: Linked Sets, posted by Stephen Bauman on Sun Feb 23 22:32:49 2025. FYI, the BRT/BMT M/M’s cabs had the same typeof cab door system as the IRT. When the ABs were still singles, the cabs were folded over the controls and a passenger seat was lowered to permit unused cabs to be available to passengers. The IND R-1s and R-4s also had something similar although it was a bit more convoluted. I believe it required an additional folding section to the cab door, but The B of T removed all the hardware when it was decided to abandon the practice and that feature was not included on the R-6s and up. When the steels were unitized into B units, the cab doors were folded across the space where the controls had been. The practice of allowing passengers into the unused cabs was ended due to the possibility of passengers leaving undesired “deposits” in the unused cabs. |
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| (1639426) | |
Re: Linked Sets |
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Posted by Stephen Bauman on Mon Feb 24 07:28:23 2025, in response to Re: Linked Sets, posted by Andrew Saucci on Sun Feb 23 23:38:45 2025. Now that the IRT, BMT, and IND are all owned by the city, and unification happened a long time ago, is this patent still an issue?Sometimes the reason behind a design decision gets lost. The design may be repeated even though the reason behind it may no longer be valid. |
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| (1639428) | |
Re: Linked Sets |
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Posted by Jersey Mike on Mon Feb 24 09:16:20 2025, in response to Re: Linked Sets, posted by Stephen Bauman on Sun Feb 23 22:32:49 2025. It's largely a function of the labor cost model. When trains were expensive an employees were cheap, it made sense to run shorter, more frequent trains and employ the hostlers and yard workers to vary trainset length over the course of a day.Today its cheaper to buy more railcars and leave them in fixed sets, even if those cars run more miles as a result, than to pay the costs of dynamic set management and more frequent service. |
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Re: Linked Sets |
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Posted by Chris R16/R2730 on Mon Feb 24 09:36:02 2025, in response to Re: Linked Sets, posted by LuchAAA on Mon Feb 24 01:23:40 2025. The latter is probably why the R62/68 contracts called for single units. Availability in the early 80s was atrocious. By the mid 90s it had improved to the point that permanent linkage was feasible. |
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Re: Linked Sets |
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Posted by Train Dude on Mon Feb 24 10:52:06 2025, in response to Re: Linked Sets, posted by Chris R16/R2730 on Mon Feb 24 09:36:02 2025. Except, linking was not feasible. It was necessary. |
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Re: Linked Sets |
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Posted by Chris R16/R2730 on Mon Feb 24 12:08:45 2025, in response to Re: Linked Sets, posted by Train Dude on Mon Feb 24 10:52:06 2025. Why? |
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Re: Linked Sets |
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Posted by Chris R16/R2730 on Mon Feb 24 12:08:46 2025, in response to Re: Linked Sets, posted by Train Dude on Mon Feb 24 10:52:06 2025. Why? |
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Re: Linked Sets |
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Posted by Italianstallion on Mon Feb 24 14:48:26 2025, in response to Re: Linked Sets, posted by Stephen Bauman on Sun Feb 23 22:32:49 2025. Your first two aren’t disadvantages, just alternative solutions. |
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Re: Linked Sets |
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Posted by Steve B-8AVEXP on Mon Feb 24 16:59:27 2025, in response to Re: Linked Sets, posted by randyo on Mon Feb 24 03:43:47 2025. Your last sentence reminds me of my first AA ride on May 7, 1967. My father noticed on of the unused cabs on the IND old timers and wondered out loud if that was a john. I said probably not. |
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Re: Linked Sets |
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Posted by Andrew Saucci on Mon Feb 24 19:01:11 2025, in response to Re: Linked Sets, posted by Steve B-8AVEXP on Mon Feb 24 16:59:27 2025. The bathroom on an LIRR M-1 or M-3 wasn't much larger than an operator's cab as it occupied the space opposite the cab. |
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Re: Linked Sets |
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Posted by Train Dude on Mon Feb 24 21:06:32 2025, in response to Re: Linked Sets, posted by Chris R16/R2730 on Mon Feb 24 09:36:02 2025. Except, linking was not feasible. It was necessary. |
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Re: Linked Sets |
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Posted by Train Dude on Mon Feb 24 21:21:34 2025, in response to Re: Linked Sets, posted by Chris R16/R2730 on Mon Feb 24 12:08:45 2025. I won't speak to the R-62s because I was never involved with A division cars but will speak of the R-68s. Unlike the R-46 fleet, R-68s were standard smee vehicles. The H2C couplers and the electric portions were standard on most cars yet there were failures. When the GOH programs were being planned, the H2 coupler head was no longer being manufactured. Hence by linking the cars, where 8 couplers would have been necessary only 2 were now needed. All of the out of gauge couplers were purged. In addition, 6 electric portions, 6 master door controls 6 brake valves, 6 master controllers, 2 compressors and 1 converter were eliminated from each 4 car set. This enabled greater attention to be paid to the remaining components. The fleet MDBF more than doubled as a result while cutting maintenance costs. |
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Re: Linked Sets |
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Posted by BLE-NIMX on Tue Feb 25 12:44:50 2025, in response to Re: Linked Sets, posted by Train Dude on Mon Feb 24 21:21:34 2025. I remember the NYAB green R10 air compressors aboard the early first hundred or so R68s and WABCO D4 on the 2800s and up through the R68As. If I recall the R10 compressors were pulled in the early 90s when they started linking them as they leaked down when the governors shut off. |
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Re: Linked Sets |
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Posted by randyo on Tue Feb 25 16:29:39 2025, in response to Re: Linked Sets, posted by BLE-NIMX on Tue Feb 25 12:44:50 2025. R-10s were NOT linked. |
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Re: Linked Sets |
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Posted by BLE-NIMX on Tue Feb 25 22:31:18 2025, in response to Re: Linked Sets, posted by randyo on Tue Feb 25 16:29:39 2025. Linking the R68s. Not the R10s. That's what I meant |
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Re: Linked Sets |
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Posted by randyo on Wed Feb 26 03:48:19 2025, in response to Re: Linked Sets, posted by BLE-NIMX on Tue Feb 25 22:31:18 2025. OK. |
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