|
|
| SMEE (243761) | |
 |
|
| Home > SubChat | |
[ Post a New Response | Return to the Index ]
[1 2] |
||
|
|
Page 1 of 2 |
|
|
| (243761) | |
SMEE |
|
|
Posted by Brighton Private on Fri Apr 21 11:19:27 2006 This may be a dumb question, but I've seen the acronym SMEE used in connection with a variety of mid-20th century subway car models. What does it mean? |
|
|
| (243768) | |
Re: SMEE |
|
|
Posted by Allan on Fri Apr 21 11:28:09 2006, in response to SMEE, posted by Brighton Private on Fri Apr 21 11:19:27 2006. Let me say this before someone else does: Smee is Captain Hooks first mate.But to be serious: SMEE Straight-air Motor Car Electro-pneumatic Emergency. A type of train braking system. SMEE uses electrical signals to rapidly equalize braking effort in a train. It also allows each car in the train to draw compressed air for braking from its own supply, rather then depending on that from the car where the operator is located. |
|
|
| (243774) | |
Re: SMEE |
|
|
Posted by Brighton Private on Fri Apr 21 11:33:45 2006, in response to Re: SMEE, posted by Allan on Fri Apr 21 11:28:09 2006. Thank you.So if I understand correctly, it differs from conventional air brake systems in that it uses electronic signals, rather than variations in the air-line running through the train, to activate the brakes? Or are the electronic signals used only to equalize braking effort, parallel to the more conventional approach? Thanks. |
|
|
(Sponsored) |
iPhone 6 (4.7 Inch) Premium PU Leather Wallet Case - Red w/ Floral Interior - by Notch-It |
|
| (243787) | |
Re: SMEE |
|
|
Posted by Railman718 on Fri Apr 21 12:25:13 2006, in response to Re: SMEE, posted by Allan on Fri Apr 21 11:28:09 2006. Wow thats Old School for you. I always thought(well i was taught this in Schoolcar never knew there was a "older" term for it) SMEE Meant Self-Lapping-Mechanical-Electrical-Equipment.You are never too old to learn something new! :o) |
|
|
| (243815) | |
Re: SMEE |
|
|
Posted by Allan on Fri Apr 21 13:57:07 2006, in response to Re: SMEE, posted by Brighton Private on Fri Apr 21 11:33:45 2006. I have never quite fully understood it myself.As I once heard it when the brake handle is moved to the proper position the train motors act as reverse generators "pushing" electricity back into the 3rd rail, effectively slowing the train. At about 9 MPH the air brakes kick in to bring the train to a stop. I don't know how accurate that description is but rest assured that there are plenty here who will jump to correct me. |
|
|
| (243818) | |
Re: SMEE |
|
|
Posted by Railman718 on Fri Apr 21 14:01:03 2006, in response to Re: SMEE, posted by Allan on Fri Apr 21 13:57:07 2006. That is called "retarding" the motors(dynamic braking).Then Friction kicks in. If Schoolcar Memory serves me right. |
|
|
| (243951) | |
Re: SMEE |
|
|
Posted by VictorM on Fri Apr 21 18:55:18 2006, in response to Re: SMEE, posted by Brighton Private on Fri Apr 21 11:33:45 2006. That's right - electrically operated air brakes activate much faster than brakes that require variations in train line air pressure to activate. They also activate the brakes much more evenly. It should be noted that, while electrically operated air brakes have been in subway use for nearly a century, most of the braking in subway cars built in the last 60 years is done, in effect, by converting the traction motors to generators, and dissipating the energy thus created through high capacity resistors, the air brakes providing only a supplemental braking force. |
|
|
| (244040) | |
Re: SMEE |
|
|
Posted by tracksionmotor on Fri Apr 21 23:26:49 2006, in response to Re: SMEE, posted by VictorM on Fri Apr 21 18:55:18 2006. Well, kind of. Primary braking always remains pneumatic. When the operator applies brakes in a DC traction motor set-up, the group box cycles the motor wiring as self excited generators (motors are series wound...field and rotor) to provide power in high rpm to the resistive grid. You can turn the shaft of a alternator/generator coupled to a load by hand without any resistance at a slow speed but once you reach a speed of electrical excitation, you encounter resistance. The resistance at higher speeds in a trainset is called 'dynamic braking.' In the group box there is a simple electrical mechanism that senses the generator current manufactured by the tracksionmotors. As the trainset slows down by dynamic braking, the amount of current generated gets smaller. When the current generated goes down to about 100 Amperes DC (10 MPH or so,)pneumatic braking is engaged. IF a particular car has a dynamic braking failure, upon inspection the cars truck (s) will have very noticible brake shoe wear as compared to others in the trainset. In the event of dynamic braking failure, the specific car will have engaged pneumatic braking positively...very reason why primary braking is pneumatic. IF you were to Brake In Emergency at a high speed...engaging a propulsion failure...air is numbah ONE. Worst case scenario: loss of third rail/catenary/trainset total LVDC trainline battery and control systems...R142 master controller joystick won't play PackMan and bumping into emergency does nothing because POU magnet valves allow coast. Reach up and pull BIE chord...conductors valve evacuates 'straight air' to atmospheric pressure, magnet valves drop and reserve air engages emergency braking. Mucho FLATZ. This has been Dynamic Braking 101. Tracksionmotor is RRCI Peter |
|
|
| (244042) | |
Re: SMEE |
|
|
Posted by BLE-NIMX on Fri Apr 21 23:37:58 2006, in response to Re: SMEE, posted by Railman718 on Fri Apr 21 14:01:03 2006. Schoolcar was full of retarded motors. |
|
|
| (244049) | |
Re: SMEE |
|
|
Posted by tracksionmotor on Sat Apr 22 00:01:04 2006, in response to Re: SMEE, posted by Allan on Fri Apr 21 11:28:09 2006. One of my buddys pointed out my work on SMEE carzzz but I just had a hard time with association. Every truck has an independent Pneumatic Operation Unit (brake panel) that uses electromagnetic valves to operate brake systems in sync subway carzzz and heavy passenger rail. Freight does not...trainline is straight air and brakepipe....brake application is not synchronus because it takes time for the air pressure to reach the furthest cars....braking should start at the end of the consist.To overcome braking sync in heavy freight, radio controlled locos are inserted in the middle. A real situation was pointed out to me in class...there was a seperation...the operator noticed a 'loss of load' on his TOD...the back half was operating ten miles behind when he stopped...it stopped too. Straight air Motor car Electro-pneumatic Emergency...SMEE. Thank you for the refresher....SMEE is what I do. Kudos to EngineBrake. RRCI Peter |
|
|
| (244057) | |
Re: SMEE |
|
|
Posted by tracksionmotor on Sat Apr 22 00:14:39 2006, in response to Re: SMEE, posted by Railman718 on Fri Apr 21 12:25:13 2006. Me too. I thought SMEEs were olde trainzzz too...brake towers. I LEARNED something tonight too and applied it to what I work...my M7s are SMEEs. Of course it it more fun when the brake tower is not self-lapping...application...release...application...release. RRCI Peter |
|
|
| (244076) | |
Re: SMEE |
|
|
Posted by Jeff H. on Sat Apr 22 01:09:35 2006, in response to Re: SMEE, posted by BLE-NIMX on Fri Apr 21 23:37:58 2006. Ouch! |
|
|
| (244078) | |
Re: SMEE |
|
|
Posted by Jeff H. on Sat Apr 22 01:13:50 2006, in response to Re: SMEE, posted by Brighton Private on Fri Apr 21 11:33:45 2006. So if I understand correctly, it differs from conventional air brake systems in that it uses electronicsignals, rather than variations in the air-line running through the train, to activate the brakes? Or are the electronic signals used only to equalize braking effort, parallel to the more conventional approach? To call it "electronic" is stretching it, as there is nothing more than electromechanical logic involved. SMEE is an electro-pneumatic overlay system, similar to EP braking on other rail cars. There are two trainline wires, Apply and Release, which control service braking. Thers is ALSO a trainline air pipe called the Straight Air Pipe (SAP). The two signals, electric and pneumatic, are synchronized. In the event of failure of either system, the other one will operate without any further effort on the motorman's part. However, when operating purely pneumatically, the brakes will apply and release more sluggishly; it is almost like running a freight train. Note that "SMEE" deals purely with the braking. It so happens that all NYC SMEE subway cars also came with dynamic braking, but it is possible to have a SMEE system with purely friction braking. Dynamic Braking != Electropneumatic Braking. |
|
|
| (244080) | |
Re: SMEE |
|
|
Posted by Railman718 on Sat Apr 22 01:18:47 2006, in response to Re: SMEE, posted by BLE-NIMX on Fri Apr 21 23:37:58 2006. Oh yeah no doubt i can bear witness to that! Thank Goodness 99% of them who started with me are not working down here anymore(except ONE,hes the B Div's problem child now). |
|
|
| (244081) | |
Re: SMEE |
|
|
Posted by Jeff H. on Sat Apr 22 01:19:21 2006, in response to Re: SMEE, posted by Railman718 on Fri Apr 21 12:25:13 2006. That is a misconception which has taken root in RTO and spreadto other departments, and it is now impossible to convince people of the correct meaning of the acronym. Basically, some unknown ignorant person put that wrong definition in a training manual 20 or 30 years ago, and because it sounded plausible, it got copied over and over again until it became TA "gospel". Ask people who worked for the TA in the 50s or 60s and they'll know the correct answer, as would anyone who is knowledgable of air brake systems. |
|
|
| (244288) | |
Re: SMEE |
|
|
Posted by Olog-hai on Sat Apr 22 16:24:51 2006, in response to Re: SMEE, posted by Allan on Fri Apr 21 11:28:09 2006. Let me say this before someone else does: Smee is Captain Hooks first mate.Captain Hook, not Captain Hooks.  |
|
|
| (244374) | |
Re: SMEE |
|
|
Posted by Alex L. on Sat Apr 22 18:17:16 2006, in response to Re: SMEE, posted by Olog-hai on Sat Apr 22 16:24:51 2006. Try: Captain Hook's first mate. |
|
|
| (244376) | |
Re: SMEE |
|
|
Posted by tracksionmotor on Sat Apr 22 18:18:58 2006, in response to Re: SMEE, posted by Allan on Fri Apr 21 13:57:07 2006. With application of brakes, relays engage contactors that rewire the motors into generators and 'push' electricity into the resistive grid banks (those cages undercar) and not the third rail. A electric circuit senses the amount of current generated and disconnects the grid, applying air brakes. when the generated current falls below an amount of 100 Amperes...a speed of about 10 MPH or so. This is why it is very important to check 'application and release' contacts for proper operation of the brake tower...trainset needs to see an electrical signal to control all brakes of all cars in SMEE. I teach this stuff to crew so they have a basic understanding of what the work is.R142s I had worked on and the M7s I work on now eliminated all the electrical relays and power contactors I had become familiar with, The computer system senses wheel rotation (speed), braking (pressure sensors) and current generated to determine if its dynamic or pneumatic braking. The old trains had something called 'lock-out' where relays locked out the brakes when traction power was applied...kind of not being able to step on your cars accelator pedal and the brake at the same time. R142s and M7s remain SMEEs because trainline braking is basically electric signals. You mentioned 'pushing electricity into the third rail.' This is called REGENERATIVE BRAKING. Idea is that power generated does not get wasted generating heat in the resistive grid but goes back into the third rail. Problem is the third rail is not a good conductor of electricity and a trainset engaging dynamic braking needs to find a closeby train to push power into....does not always work! On hybrid automobiles, dynamic braking is standard, When you drive uphill, your engine basically provides the power to go up. When you start to go downhill and apply brakes to slow down, the computer rewires electric traction motor(s) as generators to charge batteries ONLY if you apply brakes and not coasting down the hill. Different systems work differently...some vehicles use an engine/generator/electric motor configuration (like Diesel locomotives) while others use a combination of two wheel drive and other two wheels are electric motor driven (like Ford Escape 4WD.) Concept remains the same. Thanks for giving me the opportunity to 'jump.' My TARDIS is overdue for service. I love this stuff. RRCI Peter |
|
|
| (244381) | |
Re: SMEE |
|
|
Posted by New Brunswick Station on Sat Apr 22 18:31:28 2006, in response to Re: SMEE, posted by tracksionmotor on Sat Apr 22 18:18:58 2006. Time and Relative Dimension in Space. It's a Gallifreyan Time Lord vehicle. |
|
|
| (244493) | |
Re: SMEE |
|
|
Posted by R32 3545 on Sat Apr 22 21:54:44 2006, in response to Re: SMEE, posted by tracksionmotor on Sat Apr 22 00:01:04 2006. May be this is also a dumb question...If trains are SMEE operated (compressor and reservoir in each car), then what is the purpose of the two air pipes exist between two rolling stocks? |
|
|
| (244539) | |
Re: SMEE |
|
|
Posted by tracksionmotor on Sat Apr 22 22:57:11 2006, in response to Re: SMEE, posted by R32 3545 on Sat Apr 22 21:54:44 2006. One air pipe is trainline...'straight air'...meaning all operational compressors maintain full air pressure for all cars (130 to 150 PSI.)The other airpipe is 'brakepipe' which is also trainline. While the entire consist depends upon SMEE controls for braking and propulsion control for all cars, trainline brakepipe attempts to insure brake pressure equalisation for all cars. IF a car encountered SMEE brake control failure, common brakepipe trainline would continue to operate that specific cars brakes. Brakepipe is the braking pressure...0 PSI for full release,11 PSI for minimum brake, 42 PSI for maximum brake (full service) and 49 PSI for Brake in Emergency (varies by car specifications.) Now for an answer for what is not a 'dumb question.' SMEE is electrical control so if all cars had air compressors...two hoses would not be needed BUT SMEE is also a safety redundant system in passenger rail...one hose carrys air pressure and the other controls application of brakes. IF an accident occured where the straight air hose broke or the emergency valve was activated, the air pressure would drop rapidly and trainset would Brake In Emergency powered by air resevoirs...redundant safety system. FREIGHT is not SMEE...it has two hoses and no electrical connections. One hose, straight air, provides air pressure. Each car has it's own reserve air resevoir. The other hose is brake pipe...what pressure contained controls all the brakes of all cars. All CARS, whether passenger rail or freight, must maintain at least 90 pounds of air pressure all the time...cut the hose and all cars Brake In Emergency. Getting back to freight, their air brakes are under spring pressure that requires maximum air pressure for no braking and zero pressure for full braking...opposite of SMEE. If a freight car has a major leak or hose cut or accident of straight air pressure, BIE. IF the brake pipe hose is cut in opeation, maximum braking is applied. Freight cars have no redundant system like passenger rail. Sorry for being too tekky....this is a lot of materiel to cover in a few minutes. To break this down in a nutshell, SMEE cars with independent and compressors and resevoirs have two air pipes for redundancy to be safe. RRCI Peter |
|
|
| (244653) | |
Re: SMEE |
|
|
Posted by Jeff H. on Sun Apr 23 02:20:25 2006, in response to Re: SMEE, posted by R32 3545 on Sat Apr 22 21:54:44 2006. Tracksionmotor got it basically right but he reversed Brake Pipeand Straight Air Pipe. The Straight Air Pipe is used for normal service braking, while the Brake Pipe is a failsafe for emergency braking only (normally contains pressure, if the pressure vents, the train goes into emergency). It's very similar to the system used on tractor-trailers. |
|
|
| (244657) | |
Re: SMEE |
|
|
Posted by Olog-hai on Sun Apr 23 02:33:01 2006, in response to Re: SMEE, posted by Alex L. on Sat Apr 22 18:17:16 2006. Betcha some people at the TA are regretting coming up with an acronym that's evocative of Peter Pan characters . . . |
|
|
| (244667) | |
Re: SMEE |
|
|
Posted by tracksionmotor on Sun Apr 23 03:36:09 2006, in response to Re: SMEE, posted by Jeff H. on Sun Apr 23 02:20:25 2006. Well, I have problems with nomenclature but my understanding is that the 'straight air' trainline is the supplier of 120-150 compressed air for all pneumatic systems which includes pneumatic suspension. 'Brake Pipe' is trainline pneumatic brake pressure used for service braking. IF straight air pressure drops below 90 PSI dsue to a major air leak (like car seperation) or B3C conductor valve is activated and pressure is evacuated to atmosphere, magnet valve drops on the Pneumatic Operating Unit (Wabco/NY Air/Knorr brake panel) and applies brakes in emergency service. Check your duplex gauge!On a parked Redbird in FULL SERVICE, the duplex gauge should read 150 PSI straight air and 42 or so PSI brake pipe. Straight air is the pneumatic source and brake pipe is the pressure applied to brake load. I beg to differ........I teach this stuff. In a parked condition connected to shop power, the M7 TOD will read about 147 PSI straight air and 0 PSI brakes...automatic mechanical parking brakes. |
|
|
| (244702) | |
Re: SMEE |
|
|
Posted by TransitChuckG on Sun Apr 23 08:35:24 2006, in response to Re: SMEE, posted by Jeff H. on Sun Apr 23 02:20:25 2006. It's very similar to the system used on tractor-trailers.Thanks, Jeff. In tractor -trailers (semi-trailers), a spring brake activates in emergency situations. Look under a semi-trailer and you will see big pots on the axle. After the emergency is over , you have to unwind them. http://en.wikipedia.org/wiki/Semi-trailer |
|
|
| (244755) | |
Re: SMEE |
|
|
Posted by Brighton Private on Sun Apr 23 10:05:27 2006, in response to Re: SMEE, posted by tracksionmotor on Sat Apr 22 18:18:58 2006. Thanks. Very informative.I have a general understanding of dynamic braking but, in the pre-computerized days, was aware that in locomotives, it was operated with a different handle than the one that controlled the air brakes, so I was having a hard time understanding how, in pre-computerized SMEE cars, the motorman would operate both systems with the same brake handle. Your explanation clears that up. |
|
|
| (244757) | |
Re: SMEE |
|
|
Posted by Brighton Private on Sun Apr 23 10:13:16 2006, in response to Re: SMEE, posted by tracksionmotor on Sat Apr 22 22:57:11 2006. Excellent. Thanks. |
|
|
| (244783) | |
Re: SMEE |
|
|
Posted by BLE-NIMX on Sun Apr 23 11:35:48 2006, in response to Re: SMEE, posted by tracksionmotor on Sat Apr 22 22:57:11 2006. Peter thats the second post you said the SAP goes as high as 150. That sounds like main reservoir, not straight air. The spotting wire in emergency will flow feed valve air into the SAP when the CCO is on and the reversor key is in direction. Once the emergency contactors and car valves are in agreement, the regulating pneumatic and pendulum finger portions of the ME42/43 serves to regulate the SAP to about 70 and giving variable control over it as well to brake and release. R44 and R46s (I ran those too with stripes) had common main reseroir pipes. Their equipment read BC with inshot, BP (which indicated the car's own MR since there was no feed valve) a jewelled idiot light for snow and handbrake and the never to be forgotten P-Wire Ammeter, half an amp for release and zero amps for emergency. The R46 had a second SCM group box for dynamic braking.Jeff can correct me here as far as freight goes, each railroad car has a 3 port reservoir system known as ABDX storing two ports of maximum pressure (one for emergency air and one for controlling brake air, both at 90 PSI, all charged from the brake pipe, and one port which samples and references the air in the brake pipe as it rises or lowers dependging on the engineer actions in the cab. If the BP falls slowly (LE applying brakes) the valves inside will unport and flow stored control air to the brake cylinders until control air and BP are equal, thus the valve will seal the BC port and thus self lap. When the air rises (engineer releases) the BP rises, forcing the port valves to recharge the air in the tanks and vents the BC piping. All the while, the emergency air does not fall below 90 during BP reduction until a rapid reduction in brake pipe is detected which will initiate an emergency brake application. I don't know of any springs on freight cars. The work trains in TA had some older 100 numbered flat cars which had one big brake cylinder with push rods mechanically applying the brake shoes with some heavy springs on them to assist in releasing the brakes and most clasp type cylinders need about 5 PSI to overcome "release springs". THats my 101, now back to the show. |
|
|
| (244786) | |
Re: SMEE |
|
|
Posted by H.S.Relay on Sun Apr 23 11:41:09 2006, in response to Re: SMEE, posted by tracksionmotor on Sun Apr 23 03:36:09 2006. Peter, Jeff was correct: you have SAP and BP reversed.SAP: Pneumatic demand for braking 0/90 = none/full BP: Constant 110-150 tying the tanks. A sudden drop, or any drop below 90 will put reservoir directly to the cylinder. Maybe you're confused since the SAP is used to help charge up the train - that's a story for another day ( and better told by Jeff ) |
|
|
| (245089) | |
Duplex Gauge |
|
|
Posted by tracksionmotor on Sun Apr 23 22:27:02 2006, in response to Re: SMEE, posted by Jeff H. on Sun Apr 23 02:20:25 2006. You are correct Jeff. I sat up too late. It has been a while since I've done air brake inspections. While I could not find the details of speciffic pressure values, an old R33 inspection form indicates SAP full service at 80 psi, full release at 0 psi and snow brake at 8 psi. On the M7, brake pipe is max 150 psi and BIE is about 52 psi. There has been some confusion because a batch of M7s have the duplex gauge hooked up sdrawkcab. I learn from things like this because it forces me to review and relearn. You cannot do stuff like 3-A Backfeed test, cross over test, T/O Ind press. test and 5 wire test because trainset does not work that way. Thanks. I humbly stand corrected. |
|
|
| (245135) | |
Re: SMEE |
|
|
Posted by VictorM on Mon Apr 24 01:29:46 2006, in response to Re: SMEE, posted by tracksionmotor on Sat Apr 22 22:57:11 2006. Freight cars don't use springs for braking force. Each car has its own air tank plus a triple valve which shunts air from the tank to the brake cylinder if there's a drop in train line air pressure. When the train line pressure increases, the air tank is recharged and air is let out of the brake cylinder, releasing the brakes. |
|
|
| (245156) | |
Re: SMEE |
|
|
Posted by BIE on Mon Apr 24 04:27:25 2006, in response to Re: SMEE, posted by Jeff H. on Sun Apr 23 02:20:25 2006. " Brake Pipe is a failsafe for emergency braking only (normallycontains pressure, if the pressure vents, the train goes into emergency). It's very similar to the system used on tractor-trailers." actually, it is similar to the automatic brake used on a freight train except for the fact that the subway has only one application position, BIE. |
|
|
| (245158) | |
Re: SMEE |
|
|
Posted by Jeff H. on Mon Apr 24 04:57:30 2006, in response to Re: SMEE, posted by tracksionmotor on Sun Apr 23 03:36:09 2006. Again, no, you have it backwards. And M7 != SMEE. |
|
|
| (245159) | |
Re: SMEE |
|
|
Posted by Jeff H. on Mon Apr 24 04:58:56 2006, in response to Re: SMEE, posted by Jeff H. on Mon Apr 24 04:57:30 2006. Disregard...didn't see your other post under a different subject head. |
|
|
| (245160) | |
Re: SMEE |
|
|
Posted by BIE on Mon Apr 24 05:04:34 2006, in response to Re: SMEE, posted by VictorM on Mon Apr 24 01:29:46 2006. That would be a good description of a freight brake system of a hundred years ago. Today's freight brake uses a three part control valve which consists of a service portion, a pipe bracket portion for connecting the other two valve portions to the rest of the car air brake system, and an emergency portion This control valve is connected to a combined service and emergency reservoir as well as to the brake pipe and cylinder. In a service application, the service portion senses the service reduction in the brake pipe pressure and valves an amount of pressure from the service compartment of the reservoir to the brake cylinder proportionate to the amount of brake pipe reduction. In an emergency application, the rapid drop in brake pipe pressure triggers not only the service portion but also causes the energency portion to send all of the air from BOTH compartments of the combined service and emergency reservoir to the brake cylinder.If you really want to read the techincal information on a modern freight car control valve: ABDX O&M Bulletin ***W*A*R*N*I*N*G***: This file is 6 Megabytes. |
|
|
| (245161) | |
Re: SMEE |
|
|
Posted by Mitch45 on Mon Apr 24 05:08:26 2006, in response to SMEE, posted by Brighton Private on Fri Apr 21 11:19:27 2006. Wasn't that the name of Captain Hook's pet parrot in Peter Pan? |
|
|
| (245225) | |
Re: SMEE |
|
|
Posted by Steve B-8AVEXP on Mon Apr 24 10:01:14 2006, in response to Re: SMEE, posted by Mitch45 on Mon Apr 24 05:08:26 2006. It's a sound Felix makes when he's clearing out his sinuses. |
|
|
| (245226) | |
Parking Brake? |
|
|
Posted by Train Dude on Mon Apr 24 10:01:47 2006, in response to Re: SMEE, posted by tracksionmotor on Sun Apr 23 03:36:09 2006. My understanding is that the M-7 braking system is much like any other rail car. When in emergency, the TBUs are fed through 'Main Reservoir' air to hold the brake. It's only when the main reservoir air in sufficiently depleted that it can't hold the train that the Automatic Parking Brake is activated. Am I misinformed about the parking brake and the brake system in general? |
|
|
| (245230) | |
Re: Parking Brake? |
|
|
Posted by Dutchrailnut on Mon Apr 24 10:07:25 2006, in response to Parking Brake?, posted by Train Dude on Mon Apr 24 10:01:47 2006. Nope your right the parking brake is released with air, so if air is depleted due to compressor failure or power failure the parking brake will apply by itself.The emergency brake is a brake function based on having air on train and has nothing to do with the parking brake. |
|
|
| (245275) | |
Re: Parking Brake? |
|
|
Posted by Train Dude on Mon Apr 24 11:03:22 2006, in response to Re: Parking Brake?, posted by Dutchrailnut on Mon Apr 24 10:07:25 2006. Thank you for the confirmation. |
|
|
| (245388) | |
Re: SMEE |
|
|
Posted by VictorM on Mon Apr 24 16:47:03 2006, in response to Re: SMEE, posted by BIE on Mon Apr 24 05:04:34 2006. Thanks for the info. |
|
|
| (245441) | |
Re: SMEE |
|
|
Posted by Jeff H. on Mon Apr 24 18:55:08 2006, in response to Re: SMEE, posted by BIE on Mon Apr 24 04:27:25 2006. It is similar in the way that quick-action happens, but a majordissimilarity is that on freight train brakes (anything from F-27 triple valves to ABDX) all of the air comes through the single brake pipe. The air which eventually winds up in the cylinder under SMEE comes from the local main reservoir. There is a system of orifices and check valves which allows the reservoir to get charged up from either the brake pipe or straight air pipe if the local compressor has failed. |
|
|
| (245451) | |
Re: SMEE |
|
|
Posted by BIE on Mon Apr 24 19:07:44 2006, in response to Re: SMEE, posted by Jeff H. on Mon Apr 24 18:55:08 2006. What is the size of the SMEE brake pipe? |
|
|
| (245454) | |
Re: SMEE |
|
|
Posted by Jeff H. on Mon Apr 24 19:11:05 2006, in response to Re: SMEE, posted by BIE on Mon Apr 24 19:07:44 2006. On the older stuff it was 1" rigid pipe, but there is a lot ofcopper tubing on the more modern equipment. |
|
|
| (245490) | |
Re: SMEE |
|
|
Posted by BIE on Mon Apr 24 20:21:55 2006, in response to Re: SMEE, posted by Jeff H. on Mon Apr 24 19:11:05 2006. Ok, on mainline stuff it's 1-1/4" |
|
|
| (245565) | |
Re: SMEE |
|
|
Posted by Jeff H. on Mon Apr 24 22:28:48 2006, in response to Re: SMEE, posted by BIE on Mon Apr 24 20:21:55 2006. Yes, that is AAR spec....and it has to be schedule 80 pipe too.But NYCTA cars, like most transit vehicles, are not required to meet FRA or AAR guidelines |
|
|
| (245592) | |
Re: Parking Brake? |
|
|
Posted by tracksionmotor on Mon Apr 24 22:58:34 2006, in response to Parking Brake?, posted by Train Dude on Mon Apr 24 10:01:47 2006. Correct. The M7 parking brake is automatic like the R142 in that there is no parking brake lever. Train stops, air dumps, F end trucks engage parking brakes automatically. IF there is a lack of air in the system unable to engage BIE. You are not misinformed. Difference I see in M7s is that there is a wheel in each cab to mechanically release THE truck engaged in park. Boy did I screw up mixing up Straight Air with Brake Pipe...I do gauging automatically and do not consider 'nomenclature'. IF I remember correctly, R142s have PEBR...Parking Emergency Brake Release. In the WabCo TBU parking brake, there is a tower which contains a bladder and a spring which activates tread brake when pressure lacks...CIs doing undercar who failed to release PEBR and ratcheted the shoe out stripped the internal mechanism. The M7 Knorr disc brakes on F ends works the same way...loss of air engages mechanical presure. Both trainsets will stop, eventually lacking BIE and engaging parking brakes...it has been tested.Both MTA and industry do not spend the time to teach this stuff. You learn from hands on and working with others. I can make mistakes in descriptions but I know my stuff....I screwed up in brake pipe and straight air nomenclature...the M7 duplex gauge does not display like a R33...a parked car with stored air pressure displays 47 psi straight air and 0 psi brake pipe. I learn everday. I passed the FRA cert with 98% written and 100% practical...easy for me because I know what to inspect...then the 'book was opened' so everyone would pass. You know how dissapointed I became. There was an incident where M7s were towed out by TrackMobile and brakes failed. Somebody panicked and hit BCO...BCO is to release brakes...but the loss of pressure engaged parking brakes . Took them an hour to release brakes again. I say nothing. Thank you Steven for keeping my brain alive. I have four married pairs to get out...laborers don't follow instructions properly and I have to do a lot of repairs and corrective work actions. We get these trainzz out and just maybe I'll be back to CI work. ATB&GB RRCI Peter. |
|
|
| (245643) | |
Re: Parking Brake? |
|
|
Posted by H.S.Relay on Tue Apr 25 01:06:02 2006, in response to Re: Parking Brake?, posted by Dutchrailnut on Mon Apr 24 10:07:25 2006. Just like the 142/143. |
|
|
| (245663) | |
Re: SMEE |
|
|
Posted by TransitChuckG on Tue Apr 25 06:52:20 2006, in response to Re: SMEE, posted by Jeff H. on Mon Apr 24 22:28:48 2006. and it has to be schedule 80 pipe too.A lot of people don't understand pipe sizes. You can google it. Schedule 80 pipe has a thicker wall than schedule 40, for starters. |
|
|
| (245668) | |
Re: SMEE |
|
|
Posted by Railman718 on Tue Apr 25 07:10:36 2006, in response to Re: SMEE, posted by TransitChuckG on Tue Apr 25 06:52:20 2006. You are talking air pressure not water pressure schedule 80 pipe will do great.I can see the piping on R62A's in the cabs that are not being used. If my old plumbing schooling serves me right we called it Type K, L and M piping, M being the thinnest(will double check my code book). |
|
|
[1 2] |
||
|
|
Page 1 of 2 |
|
