Why do some windows have "screens" and others don't?

[velotrain]

I've noticed this on other engines and was curious, but finally decided to ask about it.

 

http://www.tomytec.co.jp/tomix/products/img/9169.jpg

[Kiha66]

I believe those are actually louvers, to allow air flow to cool the electrical equipment.  

[velotrain]

OK - I was led astray by their having the same trim as the actual windows, and I suspect they're glazed on models?

 

On this unit, the first and last have additional external screens.

 

http://home.a00.itscom.net/yosan/densya/omiya/hatioji10.jpg

 

I'm guessing Hokkaido engines might not have these?

[Kiha66]

I've actually seen a lot more of those add on wire screens on Hokkaido engines and DMUs.  I believe that they are to protect from tablets swinging back and hitting the locomotive/car.  I think they were on Hokkaido engines due to tablets still being used quite late in that region. 

Edited October 8, 2017 by Kiha66

[velotrain]

While I'm on it, do the raised areas of the roof with the openings serve the same purpose?

Again, these often look glazed on models.

 

On some inspection trains, there have been similar structures which I interpreted as being there to observe the catenary

.

[Kiha66]

I think those are skylights, the natural light makes working on the engine much easier than the older light bulbs could provide.

[velotrain]

1 minute ago, Kiha66 said:

I've actually seen a lot more of those add on wire screens on hokkaido engines and DMUs.  I believe that they are to protect from tablets swinging back and hitting the locomotive/car.

 

There was a previous discussion regarding welded on horizontal steel bars, and I believe Mark determined they were to keep block permission rings from breaking windows.

[Kiha66]

Yep, they mostly seem to cover windows but in Hokkaido I've seen them cover the side of the car as well.  Possibly to avoid chipping the paint and leading to rust on the car.

[velotrain]

12 minutes ago, Kiha66 said:

I think those are skylights, the natural light makes working on the engine much easier than the older light bulbs could provide.

 

Did Japan have particularly poor light bulbs at the time? 

 

We are talking mid-to-late 20th century here, and I would have thought light bulbs would be sorted out by then.

 

After all - Japan was building complex multi-level ships before WW2, and I doubt they had skylights for the workers.

[Kiha66]

I'm just judging from my own experience, florescent bulbs weren't used till much more recently from what I've seen and incandescent light a space well enough to walk through, but it is hard to see detail when working inside equipment.  I assume its the same as the reason for adding the large windows on the side of the electric units, something you don't see on modern locomotives.  And actually, the older ships did have skylights for the engine room, but after the 70s they were phased out on new builds.  

Edited October 8, 2017 by Kiha66

[nah00]

There's also the most practical consideration of all - cost. Why run wiring and have lightbulbs that will need replaced when you can simply add some more windows to allow natural light or light from an overhead shop in? It doesn't seem like much of an extra cost but multiply it by let's say 50 locomotives and it's noticeable. 

[cteno4]

Leds are now changing this quickly! 

[Kiha66]

3 hours ago, cteno4 said:

Leds are now changing this quickly! 

 

You bet!  The shop at my school recently changed all overhead lights to LED, and the power cost is so low it was easier to just leave them on all the time!  The portable battery work lights are a god send as well, it really makes it easy to light where ever you are working.  Regarding the locomotive it also lets you work inside even when all power is off, such as you'd need to do when the pantograph is down.

[cteno4]

Whole house here is now led except for the basement and shop that are fluorescent tubes, but retiring all those this winter to use led tubes. Good as the ballasts are getting so cheaply made now they are blowing in like 1-3 years, especially in the garage which can get cold in winter. Led tubes are getting cheap and more light and less than half the watts! 

 

Sure the locos have some 12v batteries for stuff and they could run some leds quite a while.

 

Jeff

[kvp]

Until the end of the 1980ies many industrial buildings had sawtooth roof, so natural light could get in and natural ventillation is provided. A more classic solution was to raise the top middle part, so smoke could get out and light could get in. Quite a lot of japanese model buildings show both styles and in the past japanese locomotives borrowed both solutions to allow light in. Modern lighting solutions allow simple flat roofs, but fixing a power supply or lighting problem with handheld lamps is not easy.

 

Older boxcab locomotives had full rows of normal windows, while later designs replaced some or all of these openable windows with ventiallation grilles and left only a few smaller fixed windows or a small row of windows on top. The main change that eliminated this was that older locomotive designs had most equipment in the center, with walkways on both sides. This allowed the developement of the classic american locomotive with open walkways, allowing usable visibility from a single cab on one end and easy maintenance. The other direction for boxcab designs was to move the equipment to the sides with a narrow central walkway. These locomotives are usually not easy to repair on the road, but could hold more equipment. Some in between japanese designs used a single side corridor with windows on one side only. Having a central corridor allows cooling on both sides and could have an easier to design weight distribution. The drawback is that the middle walkway is completly dark once the power is gone due to a fault or during maintenance when all power is intentionally turned off. The usual solution is to remove the roof and use a crane to lift out whole equipment boxes that could be repaired or replaced while outside or have openable/removable side panels that could only be accessed from outside the loading gauge. It's completly possible in the future to have a full width boxcab locomotive where you can't even enter the equipment space. This would allow even higher densitity designs, which would allow shorter locmotive lengths for the same amount of equipment, with some limitations on tunnel usage.

[Takahama Trainwatcher]

2 hours ago, kvp said:

It's completly possible in the future to have a full width boxcab locomotive where you can't even enter the equipment space. This would allow even higher densitity designs, which would allow shorter locmotive lengths for the same amount of equipment, with some limitations on tunnel usage.

 

Would you anticipate any situations where the shorter length of track over which the locomotive's weight was distributed might cause issues for the track?

[kvp]

44 minutes ago, Takahama Trainwatcher said:

 

Would you anticipate any situations where the shorter length of track over which the locomotive's weight was distributed might cause issues for the track?

Track load is usually measured based on axle load. A shorter locomotive with the same amount of axles and the same bogie types should have mostly the same effect on the track as long as the axle distances between two bogies is larger or equal to the axle distances within each bogie. Several older designs even put the inner axles on each bogie closer together than the axle distance within the bogies.

 

To increase traction power while keeping the axle loads the same, it's possible to use shorter locomotive sections with more bogies. Essentially more than 2 axle bogie, 2 bogie sections that have the bogies spaces as close as possible. Modern japanese freight locomotive design tends to move towards this and the first example was the EH10, but it took quite some time until this wheel arrangement was picked up again. Actually using these short dual bogied sections are better for the track than using 3 or more bogies under a rigid frame as axle loads more constant regardless of track curvature and gradient transitions.

 

ps: If you look at the EH800 series, then it would be possible to shorten the middle part in each section to have the same distance between the inner axles as between the axles of each bogie. The inter section axle distance is already set in the same way to mach the intra bogie axle distance. This would result in the most even load distribution on the rails. But this is purely theoretical as current loco sizes are already much shorter than in the past for the same power rating and there aren't much to gain by making them shorter as train lengths are not a serious concern. 

 

Original and 'shortened' EH800:

[Kiha66]

14 hours ago, kvp said:

. It's completly possible in the future to have a full width boxcab locomotive where you can't even enter the equipment space.

 

The new JR West diesel locomotive キヤ143形 seems to have equipment filling the body with limited interior access, so the large Louvers on the side also act as access panels to work on the machine.  It also has large windows on the side, which is unusual for such a modern locomotive. 

(I really want kato to make a  model of this one, especially in the summer form where it pulls tourist trains)