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Ever since I watched Sid's video on upgrading locomotives to Blunami, I have been thinking about upgrading my Lionel 0-8-0 to DCC. However, I don't know if I should go with 4408 or 2200 version. In his video, he used a 4408 decoder, but some forum users have used 2200 instead. Which one should I pick?

Kyle Paul, A Fellow "Train-Nerd"

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The important question is just how much current that engine draws when pulling a significant number of cars up the steepest hill or around the sharpest curve that it will encounter, at the highest speed you expect it to run under such circumstances.  The number of cars should be what you consider to be the "typical maximum" that it will pull.  If the current draw is 1A or less, the 2200 will do.  Any more, use the 4408.  That size engine should not have a "current hog" motor that would challenge the 4408.

The 4408 is still reasonably small for O scale. I managed to pack one into an Atlas SW9, along with one of their current keepers and new speaker. I was wiring to work on A/C track, so I squeezed a rectifier in there as well. It was a tight fit, but works great. Now I'm refitting another 4408 into a broken PS1 FP40PH. There's tons of room in there, so much so that I'm contemplating dead-rail and multiple speakers for it. Cheers!

Fred

@Ccriss posted:

I just learned about this. Can you retrofit post war engines with this as a pulmotors will run great on dc? This sure sounds like an interesting way to go as lionel really has dropped the the ball bad on remote control to me.

A pullmor running on DC would draw waaaay more current that even a 4408 could provide. I believe there are 8 amp DCC decoders that might be able to handle them but you  would have to add a Bluerail board if you wanted remote operation on AC track. Cost would likely be more than the engine alone is worth.

Pete

Last edited by Norton

It's easy enough to add a rectifier which will make a Pullmor motor "look" like a can motor to the Blunami.  If you search the Forum, you'll find circuit diagrams for doing this.  The motor can then be reversed by reversing polarity to the brushes, just like any DC motor.

A single Pullmor in good working condition will probably draw fewer than 3 amps under load.  The fact that most locos with Pullmor motors don't also have rubber tires is a good thing!  When the loco is overloaded, its wheels should spin, which greatly reduces current draw compared to what you would get on a rubber-tired loco at full stall.  If your diesel has two motors, that complicates things because in a worst-case scenario it would draw more than 4 amps.  Test it on the rails by snugly pinching the rear coupler (NOT by pushing down on it!)  Just make sure to disconnect the headlight, smoke, lighted passenger cars, etc., so your amp reading is limited to just the motor(s).

A couple of other challenges:  Pullmors have a flat commutator so the brushes will tend to spark more than they would on the drum-style commutator of a can motor.  This creates radio frequency interference.  That's one reason Lionel used shunted brushes and snubber capacitors in its TMCC locos with Pullmor motors.  Also, don't expect a ton of low-speed precision, because it's still a WW2-design 3-pole motor geared 8:1 to the wheels.  If you get it to work, please please post some photos and a video!

Last edited by Ted S
@Ted S posted:

It's easy enough to add a rectifier which will make a Pullmor motor "look" like a can motor to the Blunami.  If you search the Forum, you'll find circuit diagrams for doing this.  It can then be reversed by reversing polarity to the brushes, just like any DC motor.

A single Pullmor in good working condition will probably draw fewer than 3 amps under load.  The fact that most locos with Pullmor motors don't also have rubber tires is a good thing!  When the loco is overloaded, its wheels should spin, which greatly reduces current draw compared to what you would get on a rubber-tired loco at full stall.  If your diesel has two motors, that complicates things because in a worst-case scenario it would draw more than 4 amps.  Test it on the rails.  Just make sure to disconnect the headlight, smoke, lighted passenger cars, etc., so your amp reading is limited to just the motor(s).

A couple of other challenges:  Pullmors have a flat commutator so the brushes will tend to spark more than they would on the drum-style commutator in a can motor.  That's one reason Lionel used shunted brushes and snubber capacitors in its TMCC locos with Pullmor motors.  Also, don't expect a ton of low-speed precision, because it's still a WW2-design 3-pole motor geared 8:1 to the wheels.  If you get it to work, please please post some photos and a video!

Ted, Pullmors draw 3 amps because the field is in series with the armature. Put them in parallel and they draw twice as much. You can add a bridge to power the field off track voltage so only the armature is powered by the Blunami. If you want constant speed then field voltage would have to be regulated. Bottom line working with Pullmors requires more large components than using permanent magnet motors.

Pete

@TheRambles posted:

Today, I added blunami to a boxcar and I am tethering the boxcar to the loco using USB C. Pretty neat!



I see that you're using the low-current DC>DC converter/regulator that's available from many sources.  Its output capacity is limited.  Fortunately, the current draw of your loco's motor is probably low enough that the converter/regulator not overloaded.  Neat idea of using USB-C wiring components, which are OK for a low current installation like this.

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