# Bachmann K27 - How to reverse the fan?



## bobgrosh (Jan 2, 2008)

First thing to do was a brief checkout on analog DC.
Turned the switches in the smoke-box to "DC"
Turned motor off in tender.
Applied 18 volts
Headlight, cab light and marker lights are on, fan is running backward.


How do I reverse the fan?

B0B


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## Curmudgeon (Jan 11, 2008)

Backwards from what? 
Do you even know what it's for? 
Motor cooling. 
On a thick-walled, fully-enclosed Pittman can motor with no heat sinks or cooling fins. 
It really makes no difference. 
I have unplugged them and/or removed them in service already. 
I have 4 K's here (not counting my old one). 
If you feel it's that important, unplug it, unclip the pins from the plug, slide out and.......gee.......reverse them. 
I really should publish a letter from NASA stating "this is not rocket science". 

BTW, if you place a squirrel cage on the shaft in place of the flywheel, and the fan is "correct" rotation, you might get some extra "boost" at high speeds.


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## bobgrosh (Jan 2, 2008)

Posted By Curmudgeon on 01/18/2008 2:56 PM
Backward from what? 
Do you even know what it's for? 
Motor cooling. 



Yep, Motor cooling

So, What makes more sense?
 

Suck the air and smoke down the smokestack past the heating element and against the natural direction of convection onto the motor and out the bottom of the loco.
Suck cool air up from the bottom of the loco, and cary the heat out the smokestack. Where at least the smoke can be seen a little.  
 Absolutely no smoke comes out of the smoke stack. I can see plenty being made, but it is beings sucked down into the loco.
A lit cigarette held over the stack has its smoke drawn into the loco. It acts like one big smokeless ash tray.

My question had a lot to do with gaining access to the insides.

OK, So I had the loco an hour or two now, and I found the 8 screws and got it unlatched from the  front.

Inside is a DC brushless fan, so reversing the wires is a no-no. Looks like I might be able to just flip the whole fan.

Just asked because I figured you might have fixed the problem already, Oh,  I forgot, You just disconnect, rip and toss.
I'll update later if that helps.
Going to dinner now.


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## Curmudgeon (Jan 11, 2008)

There are 14 wires in a bundle preventing air flow along the inside top of the boiler. 
The fan allgedly draws air from the holes in the bottom of the firebox, by osmosis it follows the inside of said firebox to the space between the fan and the top of said firebox, and directs it towards the motor. 
Maybe it will work better with the fan reversed for your cigarette smoke, but if you have any experience at all with Bachmann smoke units, you might just say it is functioning normally, at best. 

One more piece designed by Stanley to be removed. 
Oh, and I hear The Bach-Man has been telling folks at shows that Stanley DID design the electronics. 

Your best bet is to yank the fan and mount it on the floor of the firebox to draw air in and pressurize the boiler. 
But, you knew that, right?


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## jimtyp (Jan 2, 2008)

Mine smoke unit works fine, but both the front and rear light is on going forward and reverse, i.e. non-directional lighting. Anyone have that issue?


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## Curmudgeon (Jan 11, 2008)

Had to go dig mine out of the bottom of the dumpster to read it.
Didn't even see it was brushless./DesktopModules/NTForums/themes/mls/emoticons/whistling.gif

Still, best bet is a full re-mount on the floor./DesktopModules/NTForums/themes/mls/emoticons/hehe.gif

Jim- Best ask Stanley.
He designed it, and there of course is no problem./DesktopModules/NTForums/themes/mls/emoticons/doze.gif

Me?


I yanked the LEDs for GOWs, and re-wired.
They certainly gave you enough wires to use./DesktopModules/NTForums/themes/mls/emoticons/w00t.gif

Gawd, these emoticons are fun!/DesktopModules/NTForums/themes/mls/emoticons/tongue2.gif

TOC/DesktopModules/NTForums/themes/mls/emoticons/shocked.gif


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## Mike Reilley (Jan 2, 2008)

FINALLY....I see that you are having fun!!! If I'm reading this right TOC...you emptied the boiler of electronics...put in your own chuff system...changed the lights....etc. etc...and are recommending that the cooling fan be installed in the bottom of the engine. Did you have to do anything to the motor or drive train on the engine....noise suppression, screw tightening, realignment, etc? Did you do anything special to make RC work?


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## Road Foreman (Jan 2, 2008)

Bob,

If it is a brushless motor you can reverse 2 wires & that should make it run the other direction..  They work just like a 3 phase motor..

BulletBob


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## bobgrosh (Jan 2, 2008)

Posted By jimtyp on 01/18/2008 4:43 PM
Mine smoke unit works fine, but both the front and rear light is on going forward and reverse, i.e. non-directional lighting. Anyone have that issue?


MY headlight comes on forward but not reverse, I have no backup light at all. (switches in DCC position.)

REVERSING THE FAN

There are two long black screws at the front, two shorter silver screws at the rear. Look closely at the front black one on the fireman side, in was pinching  the wires going to the smoke-box, Inspect and tape them up.
remove all four screws, discard the two longer black screws. Flip the fan over, install the two shorter screws in opposite diagonal corners. WARNING - DO NOT USE THE LONGER BLACK SCREWS WITH  THE FAN REVERSED.


Prior to reversing the fan all I got was an occasional puff or pop when the tube peculated. All the rest of the smoke was sucked back down the stack
Now with the fan reversed and 13.2 volts or more on the rails I get a continuous stream of smoke even with the spark arrestor installed


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## bobgrosh (Jan 2, 2008)

Fan should look like this when reversed.









and 
Instead of the smoke being sucked down the smokestack, it should look like this...








B0B


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## Dave F (Jan 2, 2008)

Why am i imagining TOC's K-27 looking like a C4400-9 when he gets finished.....


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## jimtyp (Jan 2, 2008)

I am having a problem with the smoke unit making a popping noise and spitting fluid. Anyone else have this issue?


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## bobgrosh (Jan 2, 2008)

Posted By jimtyp on 01/22/2008 10:09 AM
I am having a problem with the smoke unit making a popping noise and spitting fluid. Anyone else have this issue?


Yes.
If it does NOT make the popping noise, it is not working properly. 
What you are hearing is the percolation. 
The heating coil is a nichrome wire wrapped around the outside of a stainless steel tube. Inside the tube is a small short carbon rod. The fluid is drawn up around the rod by capillary action where it is heated and turned to smoke. The fluid actually percolates like an old coffee maker and blows smoke rings out the stainless steel tube. The smoke rings are not intended, the purpose is to move the smoke created out the tube. If the smoke allowed to sit in the tube, (or at the surface outside the tube) it will re-condense and very little usable smoke will be produced.

When it does that, it is working properly. On the Kay, the coil is about 56 ohms. At 12 volts the tube percolates. The coil is powered by an LM7812 voltage regulator so the tube can not get too hot. 

If it gets too hot, the fluid vaporizes inside the bottom of the tube below the small carbon rod and forces the fluid out the bottom of the tube,  starving the tube of it's supply of fluid and preventing it from percolating. The only smoke produced is at the surface of the fluid in the reservoir, and without a fan to blow the smoke away from that small junction, you will not get very much smoke. 

If the coil does not get hot enough, the tube will not percolate, there may be enough heat to produce a small amount of smoke where the surface of the fluid meets the hot exposed part of the coil. For example, the regulator on the three truck shay only put out about 9 volts. You only got 9 volts to the coil no mater how much higher your track voltage was. The only fix for the Shay was to put in a 12 volt regulator, or replace the smoke unit with a 5 volt version and add a matching 5 volt regulator.

OK, So if the popping noise is a GOOD thing, what about the spitting?
The fluid that comes with the Kay, and Shay is a light oil, It is too thick. Try a thinner fluid . I use LGB smoke fluid in the Kay and the Shay. Much less splattering and, the splatters that do happen quickly evaporate so as not to leave an oily mess on the boiler and smoke-box.

B0B


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## jimtyp (Jan 2, 2008)

Thanks for the insight Bob. I'll try a thinner fluid but I'm thinking of replacing the smoke unit. I don't run smoke all the time but when I do I like it to really smoke. 

I did notice one thing I thought was kind of cool on this smoke unit. If you don't reverse the fan some of the smoke, while idle, will come out along the sides and back by the cab. Have you seen that?


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