Questions that you've always been too embarrassed to ask

 
  Roachie Chief Commissioner

Location: Kadina SA (formerly NSW)

I thought I'd kick-off a new thread where people can ask "silly" questions that have nagged at them.

My question is: Why do diesel locos seem to have a large number of air hoses either side of their couplers? Back in steam days there was usually only one air hose....the exception I am aware of being the AD60 class Garratt, which had 2 hoses...one either side of the coupler.

I'd guess that one of the "extra" hoses is to couple the air systems together when multiple locos are in a "lash-up" so they have the benefit of all the locos' air tanks. I don't recall seeing ALL of the various hoses ever hooked up in any pics I've seen.

Roachie

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  KRviator Moderator

Location: Up the front

There's 4 hoses either side of the coupler on most loco's, numbered 1-4.

#1 is the Brake Pipe that has been around since Noah was a boy.

#2 is the Main Resevoir, that is used to supply MR air to all loco's for things like brakes, horn, wipers, electro-pneumatic contactors and in the case of wagons, top & bottom doors as well as supplementing the BP in keeping the wagon air reservoirs topped up.

#3 is the Independent Brake, used only on loco's & some "B wagons" in coal service.

#4 is the Independent Release, though some know it as the Bail Off. When you make a trainbrake application, the independent will also apply causing the train to bunch up on the loco's. To avoid this, when you apply the brake, you also bail off, the loco brakes stay released and the train stays nicely stretched.

You "should" see hoses 1-4 hooked up between loco's, usually all on one side, but not necessarily, it depends on the bloke who did 'em up. There are occasions where certain faults won't allow all 4 hoses to be hooked up, but that goes a lot deeper than a general overview.

  EFB5800 Chief Train Controller

Location: On my office roof.
Stoopid Q #2.
In WA they only have 3 pipes each side. #3 is called 'straight air brake', there's no #4. Is this compatible with the #3 pipe in a 4 pipe set up? And, if so then why don't they bother with the #4, and even go to the extent of removing it from 'foreigners' that are moved over there permanently?
  Greensleeves Chief Commissioner

Location: If it isn't obvious by now, it should be.

One from me:

With electric trains (or trams for that matter), you need a complete circuit for the motors to work. I've only ever seen electric units running from a pantograph or third rail but never at the same time, so does the unit receive both polarities (for lack of a better term) through the panto, or if not, how is the circuit completed?

  Graham4405 Minister for Railways

Location: Dalby Qld

how is the circuit completed?
"Greensleeves"


Through the contact of the wheels on the rails back to earth.

  Greensleeves Chief Commissioner

Location: If it isn't obvious by now, it should be.



how is the circuit completed?
"Greensleeves"


Through the contact of the wheels on the rails back to earth.

"Graham4405"


Ah so you get, say, positive through the panto and negative through the rails. How does this affect track circuitry though for level crossing bells and the like, especially when diesels run over those tracks?

Or did I miss the idea there Confused
  Fireman Dave Chief Commissioner

Location: Shh, I'm hiding

[quote:45efe7f2b5]Stoopid Q #2.

In WA they only have 3 pipes each side. #3 is called 'straight air brake', there's no #4. Is this compatible with the #3 pipe in a 4 pipe set up? And, if so then why don't they bother with the #4, and even go to the extent of removing it from 'foreigners' that are moved over there permanently?[/quote]

The number 4 pipe is an extra pipe to exhaust the brake cylinders quicker than just the single number 3 pipe. It's only really required where more than 2 loco's are used, though it is always used when provided.

I've got no idea why the WAians don't use the number 4 pipe.

  The railway dog Junior Train Controller

Why, when you open a packet of Kadee couplers, is the bit you actually want the only bit that doesn't cascade out of the packet into your hand, & possibly the floor?
Or should this question be  in a metaphysical thread?
  appleby Deputy Commissioner

Location: South of the Tweed - In Canberra.
What this thing is on the end of the BU:

  petan Chief Commissioner

Location: Waiting to see a zebra using a zebra crossing!

Would you like me to throw some light onto the subject? Maybe I could illuminate the subject for you?

Sorry but above is my way of saying it is the light switch. Used to see this at Roma Street on a wooden carriage train before it went to Central through the tunnel in daytime. Notice a handle on both ends so staff could manage from either side.

What this thing is on the end of the BU?
"appleby"


  appleby Deputy Commissioner

Location: South of the Tweed - In Canberra.



Would you like me to throw some light onto the subject? Maybe I could illuminate the subject for you?

Sorry but above is my way of saying it is the light switch. Used to see this at Roma Street on a wooden carriage train before it went to Central through the tunnel in daytime. Notice a handle on both ends so staff could manage from either side.

What this thing is on the end of the BU?
"appleby"


"petan"

Thanks Petan. Smile
  Graham4405 Minister for Railways

Location: Dalby Qld





how is the circuit completed?
"Greensleeves"


Through the contact of the wheels on the rails back to earth.

"Graham4405"


Ah so you get, say, positive through the panto and negative through the rails. How does this affect track circuitry though for level crossing bells and the like, especially when diesels run over those tracks?

Or did I miss the idea there Confused
"Greensleeves"


Sorry, I have no idea about that bit... Embarassed
  BHPDash8 Station Master

In regards to pipes, can anyone tell me what ESCP stands for? I have seen it stencilled  in white on F40, near SAB and MR.
  vlocity160 V/Gunzel


Here's another silly one. How do you know what brake valves (No. 4, A7EL, 26L) are fitted to locos? (i.e. without looking at them. Is it listed anywhere on technical documents etc.?)

Cheers!

  LowndesJ515 #TeamRog

Location: Not in Victoria



Here's another silly one. How do you know what brake valves (No. 4, A7EL, 26L) are fitted to locos? (i.e. without looking at them. Is it listed anywhere on technical documents etc.?)

Cheers!

"vlocity160"


It's listed in the locomotive manual and basically comes down to the locomotive driver being qualified in that type of locomotive. Some classes have a different brake valves also. X's 31 - 44 have the A7EL locomotive then X's 45 - 54 have the 26L brake fitted.

I've never seen it written down anywhere other than Training Manuals and Locomotive Manuals.

But if this helps for Victorian Locomotives;
A Class - 26L
A2 Class - No. 4
B Class - A7EL
C Class - 26L
D3 Class - No. 4
G Class - 26L
H Class - A7EL
J Class - A6ET
K Class - A6ET
L Class (Electric) - A7EL
L Class (Diesel) - 26L
N Class - 26L
P Class - 26L
R Class - A6ET (Interesting to note that R766 was at one stage fitted with 26L)
S Class - A7EL
T Class - A7EL
W Class - A7EL
X Class - A7EL (31 - 44)
X Class - 26L (45 - 54)
Y Class (Steam & Diesel) - No.4

A6ET - Engine & Tender
A7EL - Engine & Locomotive

  EFB5800 Chief Train Controller

Location: On my office roof.

Thanks Fireman Dave for the bit about 3 and 4 pipes. I spose the WAians didn't have a number 4 pipe because they never really used more than 2 units in multi much until recent times.

Regarding The Railway Dog's question about Kadee packets, thats because the coupler box sprue never seems to slide out no matter how you open the packet. It just seems to grab the card board some how. It seems to be able to block the couplers into the bottom of the pack, but can't stop those tiny spare springs from rolling on out. If you try opening it at the bottom , they either fall straight out anyway or you mash them when you cut the packet. Laughing
  vlocity160 V/Gunzel






Here's another silly one. How do you know what brake valves (No. 4, A7EL, 26L) are fitted to locos? (i.e. without looking at them. Is it listed anywhere on technical documents etc.?)

Cheers!

"vlocity160"


It's listed in the locomotive manual and basically comes down to the locomotive driver being qualified in that type of locomotive. Some classes have a different brake valves also. X's 31 - 44 have the A7EL locomotive then X's 45 - 54 have the 26L brake fitted.

I've never seen it written down anywhere other than Training Manuals and Locomotive Manuals.

But if this helps for Victorian Locomotives;
A Class - 26L
A2 Class - No. 4
B Class - A7EL
C Class - 26L
D3 Class - No. 4
G Class - 26L
H Class - A7EL
J Class - A6ET
K Class - A6ET
L Class (Electric) - A7EL
L Class (Diesel) - 26L
N Class - 26L
P Class - 26L
R Class - A6ET (Interesting to note that R766 was at one stage fitted with 26L)
S Class - A7EL
T Class - A7EL
W Class - A7EL
X Class - A7EL (31 - 44)
X Class - 26L (45 - 54)
Y Class (Steam & Diesel) - No.4

A6ET - Engine & Tender
A7EL - Engine & Locomotive

"LowndesJ515"


Ithought that they would be listed in such places. Thanks for that list there Les much appreciated for your in-depth response!

  Cubez Station Master


With electric trains (or trams for that matter), you need a complete circuit for the motors to work. I've only ever seen electric units running from a pantograph or third rail but never at the same time, so does the unit receive both polarities (for lack of a better term) through the panto, or if not, how is the circuit completed?
"Greensleeves"


The Overhead Line Equipment is constructed to provide a full circuit. When the panto is raised this creates a resistance on the circuit, and the locomotive has its own internal power circuit to run its motors. Think of it as similar to plugging in electrical equipment to a wall socket (ie. plugging in your toaster and turning on the switch)

  heisdeadjim Chief Commissioner


Imagine a giant capital letter C.

The overhead and associated structure are the upper part of the C.

The track and it's return to earth are the lower part. It's a principle in electronics that the earth is both a source and sink of electrons. A potential difference exists between the two.

The train completes the circuit.

  Greensleeves Chief Commissioner

Location: If it isn't obvious by now, it should be.
Ah, starting to get it now. Thanks guys Smile
  oscar2 Locomotive Fireman


Hi guys, wish I could remember to write down questions as there's a ton I could ask. Anyway here's three topics I've wondered about.

Q1 Communication between bankers and train engines during steam era, or pre cab radios. How did the banker know when to push? Was it just a case of feeling the train move on the flat and/or whistle heard then both engines go full throttle so to speak until the peak of the cimb is reached? What about if the train engine encountered an emergency such as an obstruction or mechanical failure, how would the banker know to ease off and come to a stop?

Q2 why do diesels remain idling for so long in yards and loops, or rail cars like explorers continue to idle when at a terminus.  Haven't noticed it for ages as I haven't been too bothered to look but I always wondered if there was a fuel saving to be had by shutting down and starting up again between movements or is it just not that big a deal? I'm sure the's a lot more to restarting a loco than a car but are there other reasons like I dunno, maintaining compressed air, batteries, that sort of thing?

Q3 Lastly, actually I forgot my third burning question but have a backup. Recently I saw on youtube Bevan Wall's upload of the out takes from A Steam Train Passes where at 8:57 onwards, 3801 enters a long tunnel and you see the fireman and driver don a long breathing mask each made from formed gal sheet connected to a hose. Obviously there to provide clean air to breathe in a tunnel but I've never seen them or read about them before. Question is, did all NSW steam locos have these and where did the hoses connect to? Did they just route to the front of the loco, anywhere away from the chimney or some kind of scrubbing equipment?

  seb2351 Chief Commissioner

Location: Sydney

In regards to the Locos idling, if they are PN it is more and more unlikely. It is almost a moral sin to dare leave a loco more then necessary in some depots, and the Church of Fuel Mising is only expected to become more militant and spread.

Whether it is always a good idea to start and stop the engines is another story.

  fzr560 Chief Train Controller

Is an excitation voltage applied to DC traction motors when dyno is selected? If so, what is the source of this voltage. Any one suggest a reference that might explain the whole process?
  seb2351 Chief Commissioner

Location: Sydney

Excitation is provided to the traction motor fielding to make them generate electricty. Now instead of turning the axles, the electricity generated is instead diverted to dynamic brake grids. These grids are variable resistors, hence when you move the controller up the dyno, your not electing notches per say but instead using more of the variable resistance.

http://www.ge.com/thegeshow/rails/#ch2

  fzr560 Chief Train Controller




In regards to the Locos idling, if they are PN it is more and more unlikely. It is almost a moral sin to dare leave a loco more then necessary in some depots, and the Church of Fuel Mising is only expected to become more militant and spread.

Whether it is always a good idea to start and stop the engines is another story.

"seb2351"

To quote the great Donald Rumsfeld??, we don't know what we don't know. When you shut an engine down, you save 18 litres per hour. When your V16 throws a leg out of bed, that is an event completely un-related to everything that has happened up to that point.

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