K27 smoke

[ironlake]

does the smoke on the k27 get blown out or does it just drift up on its own?

[Tony Walsham]

Some of it may drift up and out, but most of it gets sucked down into the loco because the motor "cooling"  fan is mounted the wrong way around.
If you can get it mounted the right way around, the smoke output through the stack becomes copious.

[ironlake]

why in the world would they mount the fan backwards?

[Bucksco]

The fan is NOT mounted backwards. The purpose of the fan is to cool the motor - not blow smoke out of the stack. If it is turned around it would be drawing air away from the motor instead of cooling it.

[NarrowMinded]

Just my $0 .02

Whether you draw air away from the motor or push it towards the motor you are still creating air flow across the surface which pulls heat away from the motor, the flow path through the locomotive should be about the same just reversed.

remember the air that cools the motor does not know it is being pushed or pulled it is just moving from a high pressure zone to a low pressure zone.

(if the hot air leaves  through holes in the bottom of the K27 and you reverse the flow you could create a vacuum pulling up road dust into your locomotive.

Just One more note: I am not familiar with the layout of the K27 one bad effect of reversing flow would be if you have electrical components that are before the fan which are being cooled by fresh cross flow towards the motor, would now be getting preheated air, just something to think about.


NM-JEff

[Bucksco]

This thread is about to dissapear. A lot of thought went into the design of the K-27. It is engineered this way on pupose. If someone chooses to modify the locomotive that's fine, but the locomotive's design should not be construed as wrong.....

[Skarloey Railway]

Surely a little common sense might apply. If, say, you live in Southern California and you only like to operate your south-facing garden rr on nice sunny days then maybe leaving the cooling system on your mostly black K27 just as it is is not a bad idea. otherwise, surely this is a judgement call as, presumably, mucking about with the cooling fan will invalidate the warranty.

[StanAmes]

Perhaps I can shed some light on the fan in the K27.

During development of the K27 it was decided to add a fan to cool the motor.  The reason was that it can get real hot in a black boiler on a hot sunny day, especially when the K is pulling a heavy load for an extended period of time.  By blowing air on the motor , the lifespan for the motor is significantly increased especially if you run your K in the sun on a hot day.

Because of the way air is circulated inside the boiler the side effect is that the smoke production is less.

I am not totally sure but I seem to remember that the later production of the K27 (identified by metal trucks on the tender) reversed the fan so that air is drawn from under the motor into the boiler and in turn more air  is produced out the stack.  This has the effect of less cooling and more smoke production.

Some users have reversed the fan in the boiler and report better smoke production without any ill effects to the motor likely in part because most of us do not operate the K in the sun on very hot sunny days for extended periods pulling a heavy load.

Hope that helps

Stan Ames

[armorsmith]

I agree with the Bach Man.  The fan is not mounted backwards, because it does not make any difference which way the fan is mounted for the purpose with which it is there.  The fan is cramped so close to the shell it does not have proper 'breathing room' anyway.  Those small fans have very little available static pressure as is, and chocking the flow in the manner it is mounted SEVERELY reduces the air the fan can move.

Removing the thread will only confirm the claims by Tony Walsham and myself.  I spend 15 years moving air professionally, the fan is wrong.

[the Bach-man]

Dear All,
The Yardmaster is correct. The fan is mounted for optimum motor cooling, not moving smoke. If you wish to change yours for smoke movement, you're on your own.
the Bach-man