4 ms·

If you are referring to backwards locomotives, the alternative name, cabForwards, should convey the idea. It's the usual arrangement of a locomotive, but revers

If you are referring to backwards locomotives, the alternative name, cabForwards, should convey the idea. It's the usual arrangement of a locomotive, but reversed, where what is usually found at the front is at the back and vice versa.

Waterluvian 5y ago
Right but what’s different between that and just running any other locomotive in reverse?
- masswerk 5y ago
  I guess, the general layout of the cab? – As I understand it, these locomotives where popular for routes including long tunnels, where the crew would have suffered seriously from the exhaust. If you intend to run the locomotive generally cab-forward, you'd probably adapt the layout and also add a proper wind screen.
  - Waterluvian 5y ago
    Oh. Derp. That makes complete sense. Thanks for helping me cross the finish line.
- Symbiote 5y ago
  From memory, from things my father and grandfather told me (both trainspotters), being taken all over Britain to preserved railways as a child, and from searching. Most locomotives for medium to long routes have a locomotive with a boiler in front, the cab/footplate where the driver and fireman work in the middle, and a tender of coal and water behind them [1]. Going backwards, there's even less view for the driver as the tender is square but the boiler round. The large wheels are the driving wheels, and they need weight on them for good adhesion. That's also why they're huge, to increase the contact area with the rail. The fireman needs to be between the tender and the firebox (under the boiler), to shovel coal in. They'll use most of the coal in the tender on a long journey, around 9 tons to go about 350 miles (550km). If you put the cab at the front, you either need some way to get the coal, or a second cab for the fireman -- but then a difficulty in communication. By the time appropriate innovations to avoid these issues were invented, steam was being replaced by diesel and electric power anyway. [1] https://en.wikipedia.org/wiki/LNER_Peppercorn_Class_A2#/media/File:Hugh_llewelyn_60532_(5371150220).jpg https://en.wikipedia.org/wiki/LNER_Peppercorn_Class_A2#/medi... Addendum: realize it isn't a given that people know the words, as you probably didn't have a trainspotter father. On that picture, the cylindrical black then green part is the boiler, full of long copper pipes over almost the full length. It's above the firebox, which is between the large driving wheels. The pistons are at the front, just under the "Blue Peter" nameplate, connected with coupling rods to the driving wheels. The small, front wheels provide stability (somehow, this is the answer I had age 7 or so). The cab is the bit with 60532 on it; there are forward-facing windows as well as to the side. There are green poles on either side of the entrance. There's the entrance to the firebox in the middle, plus valves and levers to control the amount of steam/water etc (i.e. speed). The tender has British Railways on the side, and is a separate part, semi-permanently coupled to the engine. It carries coal for the fire, and water to boil for steam. This is a long-range, powerful locomotive. Short-range ones could use smaller versions of all this, which could mean the coal/water being carried around the boiler, rather than in a tender. If you look closely at the driving wheels, you can see the brakes (acting directly on the rims) and the sanders (apply sand to the rails just in front of the wheels, to increase adhesion if they're slippery with autumn leaves). Around the front buffers (there's probably a name for the red-painted part) there is a coupling mechanism, a pipe to run air brakes, and another pipe to provide steam to heat attached passenger carriages.
  - Someone 5y ago
    > The small, front wheels provide stability (somehow, this is the answer I had age 7 or so). I think that’s correct. My understanding is this: The powered wheels are all in the same fixture. Their axes stay parallel at all times (they have to be because they are powered by a single set of linkages). To allow such wheels to go around curves, their flanges (https://en.wikipedia.org/wiki/Flange#Train_wheels https://en.wikipedia.org/wiki/Flange#Train_wheels) aren’t fitted tight to the rail. That means a train that only has driving wheels may not follow turns well, may start oscillating from left to right a bit, etc. The smaller wheels in front are there to prevent that by guiding the locomotive into bends. I guess those wheels are smaller because they need not be bigger (I guess bigger wheels have larger life spans than smaller ones, but powered ones have shorter life spans than unpowered ones, and the design aims for equal average life span of all wheels)
    - masswerk 5y ago
      > The smaller wheels in front are there to prevent that by guiding the locomotive into bends. I think, in the US these are also known as "pilot wheels" for that purpose. The need for them (or the use you get out of them) also depends on track quality. If you run on lightly built track, the improvement is significant. (Mind that track isn't fixed to the ground, it rather floats in the ballast, the stones in which the track is embedded. The built quality of the entire assembly has implications for stability and the kinds of speeds you can run on that track, especially with heavier locomotives.)

Waterluvian 5y ago

Right but what’s different between that and just running any other locomotive in reverse?

masswerk 5y ago
I guess, the general layout of the cab? – As I understand it, these locomotives where popular for routes including long tunnels, where the crew would have suffered seriously from the exhaust. If you intend to run the locomotive generally cab-forward, you'd probably adapt the layout and also add a proper wind screen.
- Waterluvian 5y ago
  Oh. Derp. That makes complete sense. Thanks for helping me cross the finish line.
Symbiote 5y ago
From memory, from things my father and grandfather told me (both trainspotters), being taken all over Britain to preserved railways as a child, and from searching. Most locomotives for medium to long routes have a locomotive with a boiler in front, the cab/footplate where the driver and fireman work in the middle, and a tender of coal and water behind them [1]. Going backwards, there's even less view for the driver as the tender is square but the boiler round. The large wheels are the driving wheels, and they need weight on them for good adhesion. That's also why they're huge, to increase the contact area with the rail. The fireman needs to be between the tender and the firebox (under the boiler), to shovel coal in. They'll use most of the coal in the tender on a long journey, around 9 tons to go about 350 miles (550km). If you put the cab at the front, you either need some way to get the coal, or a second cab for the fireman -- but then a difficulty in communication. By the time appropriate innovations to avoid these issues were invented, steam was being replaced by diesel and electric power anyway. [1] https://en.wikipedia.org/wiki/LNER_Peppercorn_Class_A2#/media/File:Hugh_llewelyn_60532_(5371150220).jpg https://en.wikipedia.org/wiki/LNER_Peppercorn_Class_A2#/medi... Addendum: realize it isn't a given that people know the words, as you probably didn't have a trainspotter father. On that picture, the cylindrical black then green part is the boiler, full of long copper pipes over almost the full length. It's above the firebox, which is between the large driving wheels. The pistons are at the front, just under the "Blue Peter" nameplate, connected with coupling rods to the driving wheels. The small, front wheels provide stability (somehow, this is the answer I had age 7 or so). The cab is the bit with 60532 on it; there are forward-facing windows as well as to the side. There are green poles on either side of the entrance. There's the entrance to the firebox in the middle, plus valves and levers to control the amount of steam/water etc (i.e. speed). The tender has British Railways on the side, and is a separate part, semi-permanently coupled to the engine. It carries coal for the fire, and water to boil for steam. This is a long-range, powerful locomotive. Short-range ones could use smaller versions of all this, which could mean the coal/water being carried around the boiler, rather than in a tender. If you look closely at the driving wheels, you can see the brakes (acting directly on the rims) and the sanders (apply sand to the rails just in front of the wheels, to increase adhesion if they're slippery with autumn leaves). Around the front buffers (there's probably a name for the red-painted part) there is a coupling mechanism, a pipe to run air brakes, and another pipe to provide steam to heat attached passenger carriages.
- Someone 5y ago
  > The small, front wheels provide stability (somehow, this is the answer I had age 7 or so). I think that’s correct. My understanding is this: The powered wheels are all in the same fixture. Their axes stay parallel at all times (they have to be because they are powered by a single set of linkages). To allow such wheels to go around curves, their flanges (https://en.wikipedia.org/wiki/Flange#Train_wheels https://en.wikipedia.org/wiki/Flange#Train_wheels) aren’t fitted tight to the rail. That means a train that only has driving wheels may not follow turns well, may start oscillating from left to right a bit, etc. The smaller wheels in front are there to prevent that by guiding the locomotive into bends. I guess those wheels are smaller because they need not be bigger (I guess bigger wheels have larger life spans than smaller ones, but powered ones have shorter life spans than unpowered ones, and the design aims for equal average life span of all wheels)
  - masswerk 5y ago
    > The smaller wheels in front are there to prevent that by guiding the locomotive into bends. I think, in the US these are also known as "pilot wheels" for that purpose. The need for them (or the use you get out of them) also depends on track quality. If you run on lightly built track, the improvement is significant. (Mind that track isn't fixed to the ground, it rather floats in the ballast, the stones in which the track is embedded. The built quality of the entire assembly has implications for stability and the kinds of speeds you can run on that track, especially with heavier locomotives.)