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Post by Deleted on Apr 22, 2006 10:12:12 GMT
In light of recent discussions on train braking, I have the following question:
If a T/Op stops his train with the TBC in 'Off And Release' or 'release' on a two-hanled train, what is holding the train whilst it is stationary? Is it simply that the deadman is not held down?
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Post by CSLR on Apr 22, 2006 10:37:48 GMT
In light of recent discussions on train braking, I have the following question: If a T/Op stops his train with the TBC in 'Off And Release' or 'release' on a two-hanled train, what is holding the train whilst it is stationary? Is it simply that the deadman is not held down? On a two handled system, the T/O will normally re-apply the brake slightly to stop the train rolling after it has come to a stop. The deadman will have no effect if the key is centred.
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Phil
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Post by Phil on Apr 22, 2006 12:00:14 GMT
On a two handled system, the T/O will normally re-apply the brake slightly to stop the train rolling after it has come to a stop. The deadman will have no effect if the key is centred. Yes, all part of what the public doesn't see and never thinks about. But I also used that technique when I was driving buses: come in to stop, come to a stand with brakes totally released (for about 1/ 2 sec or so), then reapply (foot or hand) once at a stand. Mind you, it's easier on trains....
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Post by Deleted on Apr 22, 2006 13:25:15 GMT
Tried it on BVE just now. It's bloody hard to do!
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Post by Deleted on Apr 22, 2006 13:58:47 GMT
On a two handled system, the T/O will normally re-apply the brake slightly to stop the train rolling after it has come to a stop. The deadman will have no effect if the key is centred. Yes, all part of what the public doesn't see and never thinks about. But I also used that technique when I was driving buses: come in to stop, come to a stand with brakes totally released (for about 1/ 2 sec or so), then reapply (foot or hand) once at a stand. Mind you, it's easier on trains.... That was always my style as well; in fact I still do it to a certain extent in the car. Driving a bus like that shows that you take some care in what you are doing, and helps avoid the 'shoppers shuffle' When I stopped, I would always put the handbrake on and select neutral. There is nothing worse than an auto box bus sitting there shaking away, just for the sake of selecting 'N'.
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Phil
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Post by Phil on Apr 22, 2006 14:13:30 GMT
Tried it on BVE just now. It's bloody hard to do! Not if you've done it on the real thing - it becomes second nature and you just carry it over to the simulator.
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Post by Deleted on Apr 22, 2006 14:52:35 GMT
Heh. Well, I'll have a go on the A stock on the ELL later Seemed hard to do with the C stock though (was running late after a few stations). Anyone up for trying this on the 95s on the Northern? ;D
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Post by Deleted on Apr 22, 2006 15:59:19 GMT
On the 1938 stock I seem to do a version of this, although I don't know how professional drivers would view my method.
Enter platform around 30 - 35 mph, apply brake 4 (only for a second as I want this and brake 5 if I've misjudged), easing back to brake 1 by middle of platform, then depending on conditions, coast a little way towards the stop mark, then 1-2-3-2-1 and then a quick burst of 'off and release' before brake 1 again just to stop it in the right place. As said on the conditions, it does vary from station to station, but that's my general routine.
EDIT: Some stations are such that you only get back into brake 1 around 3/4 of the way down the platform, these are stations where I would just use b1 and off to stop gently at the diamond.
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Colin
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Post by Colin on Apr 22, 2006 16:17:33 GMT
The 'professional' method is to start at the position before last (I say that as stocks do vary on positions and names) **emergency is not a normal braking position!!**, then work your way back to the least amount of brake followed by a quick 'off & release' as the train stops, then apply your 'holding brake'. So taking the C stock EP brake as an example: Start the braking in (Rheo2) Normal (keeping the (Rheo2) Maximum position available for misjudgments), then (Rheo2) Minimum, followed by Rheo1 & hold. As the train comes to a stand, it's off & release then back to Rheo1 & hold. The best way to practice is to brake nice 'n early to start with, then gradually leave it a little later each time till you get it just right. Whilst Alex's method is not necessarily wrong, passengers who are standing will notice the effect, and would have to adjust their balance to compensate
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Post by Deleted on Apr 22, 2006 16:57:17 GMT
At the risk of wandering off topic, does anyone know why mainline trains seem to brake so cautiously on the approach to stations? It's very noticeable if approaching West Ham at the same time as a c2c - they are going much slower than a District line train would by the time they reach the start of the platform.
Seems hard to believe that their brakes are worse, so it is just a question of how drivers are trained?
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Colin
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Post by Colin on Apr 22, 2006 17:15:59 GMT
You have answered you're own question there Our brakes are far superior to mainline trains, so we can stop in a shorter distance. On top of that, they're usually slowing from a faster speed - so they need a greater distance in which to stop. Transgressing even further......(adw 'n other District train ops)...... you may remember in stock training that the D stock has a 7 step relay, but only uses 4 steps? Well mainline trains use all 7 and is another part of the reason they take longer to stop. I don't know all the technical 'ins & outs' - I just remember being told that.
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Post by Deleted on Apr 22, 2006 17:42:46 GMT
Whats a 7 step relay?
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Colin
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Post by Colin on Apr 22, 2006 18:06:52 GMT
How did I know someone was going to ask? ;D ;D ;D ;D ;D I put the [adw 'n other District train ops] comment in brackets, as it was meant to be directed at stock trained staff!! Essentially the simple answer is it's part of the braking system on a D stock, and is fitted to each car. It regulates the amount of air used according to the position of the combined traction brake controller when braking. That's about as much as I need to know - and no offence, but that's about as much as you need to know. Unless one of our stock instructors want's to explain......
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Post by Deleted on Apr 22, 2006 18:08:23 GMT
I thought that the 7 step relay could apply brake pressure of one-seventh of maximum, two-sevenths etc. The four service brake positions range from one-seventh (Service 1) to five-sevenths (Service 4) IIRC, with emergency being the full seven-sevenths. Not that I really understand how this works! Where's solidbond when we need him?
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DrJimi
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Post by DrJimi on Apr 22, 2006 18:39:53 GMT
I'm fortunate that SB schooled me on the Westcode when we were building the MSTS D78 The steps are controlled by 3 wires, each going to a pilot magnet valve. Think of the operation as binary (or octal), as 1+2+4 = 7. Thus wire 1 =1, wire 2 = 2, wire 3 = 4. Thus any combination from 0 to 7 can be derived from appropriately removing voltage from each wire. Brakes off, all wires have voltage applied, thus if power fails, zero volts = brake full on. Each pilot valve allows air into the actuating cylinder, where the diameter and volume of that portion of the cylinder is different (this is where the 1:2:4 ratios happen). Progressively de-energizing the wires allows air into the 3 chambers of the cylinder, progressively raising an actuator rod that allows the air inlet valve to open further applying more air to the brake cylinders. Not knowing the relative volumes, and if the ratios are exactly 1:2:4, it's not clear to me if the steps do indeed exactly equate to "sevenths" of max brake. When we fine-tuned the MSTS D78 physics we determined that brake percentages of 30, 50, 65, 85 seemed to equate to steps 4...7 (Brake 1...4). I will leave it to the experts to decide if posting diagrams is appropriate (and correct my description if required). Note that the D78 section on TubePrune describes the electrical aspects of this also, so I don't believe this is "sensitive" information.
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Colin
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Post by Colin on Apr 22, 2006 18:45:40 GMT
I'm fortunate that SB schooled me on the Westcode when we were building the MSTS D78 The steps are controlled by 3 wires, each going to a pilot magnet valve. Think of the operation as binary (or octal), as 1+2+4 = 7. Thus wire 1 =1, wire 2 = 2, wire 3 = 4. Thus any combination from 0 to 7 can be derived from appropriately removing voltage from each wire. Brakes off, all wires have voltage applied, thus if power fails, zero volts = brake full on. Each pilot valve allows air into the actuating cylinder, there the diameter and volume of that portion of the cylinder is different (this is where the 1:2:4 ratios happen). Progressively de-energizing the wires will allow the air inlet valve to open further applying more air to the brake cylinders. Not knowing the relative volumes, and if the ratios are exactly 1:2:4, it's not clear to me if the steps do indeed exactly equate to "sevenths" of max brake. When we fine-tuned the MSTS D78 physics we determined that brake percentages of 30, 50, 65, 85 seemed to equate to steps 4...7 (Brake 1...4). I will leave it to the experts to decide if posting diagrams is appropriate (and correct my description if required). You are quite correct, and as I stated, we only use four steps out of the available seven using the 1+2+4=7 formula. As Solidbond will agree, I don't take notes when learning - something i'm regretting now as it would have been nice to quote the actual figures involved.
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solidbond
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Post by solidbond on Apr 22, 2006 23:42:58 GMT
OK - just to clarify, as Colin says, the D stock uses only 4 of the possible 7 amounts of brake available with the 7 step relay. With maximum brake pressure being 56psi (approx), that equates to 8psi per step. As Colin says, (and adw MISunderstood ;D) the D stock doesn't use the first 2 steps on their own. Thus, Service 1 is 3/7ths, ie 24psi, Service 2 = 4/7ths - 32 psi, Service 3 = 5/7ths - 40 psi, Service 4 = 6/7ths - 48 psi, with Emergency giving the full 7/7ths - 56psi And as to Colin not making notes, I can confirm this, and was pleasantly surprised at just how much he remembered at the end of the 3 week course (of course, he's forgotten it all now, and has got nothing to refer to, but - hey - there you go ;D ;D ;D ;D)
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Post by Deleted on Apr 23, 2006 8:34:44 GMT
Thanks for the information folks. I'd forgotten that there was a 'Rheo 1 and Hold' position on the TBC. I'll take my seat at the back of the class now.
It always suprises me that LU train braking systems operate at only <56psi. As many will know, most buses and lorries systems are at about 120psi. Does anyone here know why trainline air is normally only about 60 psi?
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Post by Deleted on Apr 23, 2006 17:35:44 GMT
As Colin says, (and adw MISunderstood ;D) the D stock doesn't use the first 2 steps on their own. Thus, Service 1 is 3/7ths, ie 24psi, Service 2 = 4/7ths - 32 psi, Service 3 = 5/7ths - 40 psi, Service 4 = 6/7ths - 48 psi, with Emergency giving the full 7/7ths - 56psi Oh dear. Looking good for my I/O interview on Thursday!
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Post by Deleted on Apr 23, 2006 17:51:23 GMT
Good luck adw
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Post by mowat on Apr 24, 2006 13:08:40 GMT
I simulate westinghouse brakes on the BVE4 1938ts by using braking positions 1 to 4 as the ep brake and 5 as the westinghouse brake and use 1 as the lap position.
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Post by setttt on Apr 24, 2006 15:13:27 GMT
I simulate westinghouse brakes on the BVE4 1938ts by using braking positions 1 to 4 as the ep brake and 5 as the westinghouse brake and use 1 as the lap position. How the hell does that simulate the westinghouse brake?
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Post by mowat on Apr 24, 2006 15:48:49 GMT
I simulate westinghouse brakes on the BVE4 1938ts by using braking positions 1 to 4 as the ep brake and 5 as the westinghouse brake and use 1 as the lap position. How the hell does that simulate the westinghouse brake? I know it's not right but it's the closest way I can find to simulating westinghouse brakes. The way I do this is to come into the station at 30/35 mph and put the brake handle into position 5 intill the speed has reached 20mph and then move the brake handle to position 1 which I use as lap, this should stop the train in the right place somtimes another short blow in BP 5 is needed to stop in time. Try it out ;D
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Post by CSLR on Apr 24, 2006 17:12:13 GMT
I know it's not right but it's the closest way I can find to simulating westinghouse brakes. If you want to see what you can do with Westinghouse, you could always wait a little longer before braking then drop the handle and see if you can hit the 7 car mark. Note: Do not expect your guard to brew tea for you for several days after pulling this stunt. ;D
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Phil
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Post by Phil on Apr 24, 2006 17:54:32 GMT
Admin Comment:
This is not a simulator thread. I cannot move individual posts - proboards doesn't allow it, but any more comments on Westinghouse in BVE should be put into a new thread in Railway Simulations.
Further posts in this thread should be to do with the real thing please
Thanks
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prjb
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Post by prjb on Apr 24, 2006 19:45:45 GMT
In light of recent discussions on train braking, I have the following question: If a T/Op stops his train with the TBC in 'Off And Release' or 'release' on a two-hanled train, what is holding the train whilst it is stationary? Is it simply that the deadman is not held down? Getting back to the original question, once a two handled train (you must mean an A60, it's the only 2 handle LU passenger stock left) has stopped, the driver will centre the key and release the deadman. By centering the key he has applied 30psi of EP holding brake, this feature prevents a driver from centering the key when on the move thus bypassing the deadmans device (this could be done pre-OPO). I must add that I have never been stock trained on A60's and if I am incorrect on certain aspects I'm sure that there is someone on the board who has a much better knowledge than me! ;D
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Post by CSLR on Apr 24, 2006 21:10:14 GMT
In the light of the comments made by prjb, which refer to OPO two handled stock, I should clarify that my reply of 22 April referred to two handled stock in two-man operation days. On such trains, no air was put into the brake cylinder when the key was centred. It was therefore necessary to use the brake handle to apply pressure to ensure that the train did not roll out of the station. During a crew change-over the key had to be centred and there are stories of motormen having to dive in through the passenger compartment because the cab was disappearing into the tunnel. I cannot, of course, comment on the reliability of such stories.
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prjb
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Post by prjb on Apr 24, 2006 21:20:24 GMT
there are stories of motormen having to dive in through the passenger compartment because the cab was disappearing into the tunnel. I cannot, of course, comment on the reliability of such stories. I have no idea what CSLR is refering to here, this never ever happened to me (ever). If any of my ex-Guards have said differently then they are also mistaken, it must have been someone else. This never happened, ok? I shall now slide away whilst whistling a merry tune. ;D
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