I’ve seen posts regarding this topic in the past but could not find any using the forum search. I have several older Athearn BB four-axle diesels I need to repower to make them more compatible for DCC (too much current draw at present). Micro Mark has a can motor with flywheels and drive shafts on sale for $27. Has anyone used this setup to convert an Athearn BB diesel? Other posts have recommended the Kato can motor but I’d need to know what other parts are needed to install the Kato motor.
I have several older blur box locos with the ild gray round motor and cast flywheels and they run just fine with decoders.If you want an easier upgrade for your locos just use the newer Athearn flat can it just simply plugs into the chassis like the old one.
I never have done a motor swap on an Athearn blue box locomotive. I own 6 or 8 of 'em. I don’t run DCC and my Tech 4 powerpack has no trouble running four of 'em in one lashup, which is all I want to do.
You might want to use a real ammeter to measure the current draw. Betcha it is under an amp, probably 3/4 amp, worst case, drivers spinning. I think modern decoders can handle up to one amp motor current, although you need to check that on the decoder datasheet.
Have you considered cutting the brush springs?
The Kato motor is a very easy swap. It is held in with a plastic mount that has the same four screw pattern that the rubber mounts have. Just put those in the current holes and the use the screws and the motor is secure. The Kato drive train uses a dog bone system, so you will have to change the coupling on the tower gear and get a proper length dog bone. You will need to five wire the truck connections, but you should do that even if you stay with the Athearn motor.
Realize that your getting a quieter lower current draw motor. In the process, your giving up power. This will show up in a reduced draw bar force and maximum speed. The former is more important than the latter. There is a good chance you will not notice much improvement in low speed operation. It is really for sound reduction and current budget.
Larry
Hello All,
Here is a conversion tutorial for BB’s:
http://cs.trains.com/mrr/f/744/t/241180.aspx.
I just finished a conversion of a BB SW1500 (actually a NW2) to DCC.
One poster to this forum suggested to cut the brush springs in half to reduce the amperage draw on the OEM motor.
I’ve done this to all my old BB motors. I don’t have a way to measure if the amperage actually dropped but the older motors seem to run better.
It has been suggested that the wheel pickups on BB’s be isolated from the frame (BB’s use the frame as an electrical path.) I have done conversions using both the frame as an electrical path and isolating the wheel pickups from the frame, with equal success.
On this last upgrade I isolated the wheel pickups from the frame and soldered NMRA color coded wires; Red on the right pickup, Black on the left. (Digitrax sells a pack of 30ga decoder wire in the 7 NMRA compliant colors in 10-foot lengths. I picked it up for $11.99 despite the MSRP of $15.00.)
Because I was using the OEM drive components I didn’t need replace any of these. However, on another upgrade of a Model Power RS11 I used North West Short Line’s drive line components along with a motor upgrade from a 3-pole to a 5-pole motor from Atlas.
To completely isolate the OEM BB motor from the frame I swapped the pronged lower brush cover with the top one. I used a coat of liquid electrical tape on the frame where the pronged brush cover previously contacted the frame and used two layers of Kapton tape between the motor mounts on the lower brush cover to completely isolate the motor from the frame.
I then soldered Orange and Gray wires to the brush covers; as per NMRA specs.
For this conversion I installed LED lighting with the appropriate resistors. I then soldered and shrink wrapped the decoder (Digitrax D
Why cut the brush springs? What besides current reduction is happening?
I have swapped old for new several times and measured no appreciable impact in current draw or any other parameter. The old springs were short and the brushes were also shorter than the new.
What I was looking for at the time was what tune up elements had the largest impact. Cleaning the communicator and lightly oiling the motor bearings showed the largest benefit. The brush results were mixed over a sample of five. None of the changes for the brushes were worth discussing. Courious what others have seen.
Larry
I did a copy of these in the past. If you can find the decoder listed in the link, it is cake to install. Ebay and older Hobby Shops may still have some in old stock.
http://www.digitrax.com/products/retired/mobile-decoders/dh123at/
How is cutting the brush springs supposed to help? From my racing days, I know that cutting a spring actually makes it stiffer, not softer. A stiffer spring would press harder against the brush contacts creating MORE friction, not less. Maybe its the more positive brush contact making the motor work better?
The brushes only need enough pressure to keep them in contact.cutting the springs reduces the pressure on the brushes but still allows full contact .Less pressure is less drag meaning less friction meaning longer brush life and a motor that runs smoother with less drag.My F/FP 45s all have the old gray round motor they have shortened brush springs and the draw 1/2 amp or less under load.They are a bit noisey but I can keep track of them .[:D]
I’ve used the remotor kits from Micro Mark, they are installed on BB F7A&B. They are Kader motors as used in Bachmann locmotives. They are fairly easy to install and perform quite well. I plan on doing some other refits with them as $$ allows.
Mark H
Thanks for the reply Mark. Any specific things I should know about before installing one of the Micro Mark motor kits?
They have an acetyl plastic motor mount that allows you to mount the motor either vertical or horizontal (lengthwise), it slipped right into the inside cavity of the F7 fuel tank but it doesn’t glue very well, it can be held in with screws. The motor also has power leads so correct polarity can be matched to another Athearn. I run DC only, so setting it up for DCC…??
Otherwise I can’t think of any particular issues. They do work with Athearn drivelines.
Mark H
All this insulating and isolating is way overkill and unneccesary. By swapping the brush covers you create a dead air space of 3/16 between the motor bottom plate and the frame, there’s no way the two can touch., therefore no tape or anything is required. Air is a perfectly good isolater. I have done this dozens of times and never had a problem with shorts thru the motor/frame.
Once the motor has been isolated, isolating the pickups is again overkill as there is no way for them to short out the motor. For electrical pickups I just solder four wires to the brass rivets on the trucks.
As for isolating the couplers, drill and tap (available from KD) a hole in the mounting pad and use a KD draft gear box to mount the coupler in. For a body mount, build up a mounting pad behing the pilot and remove the frame pad.
I run a strip of electrical tape under the motors on my Athearn conversions.It may be overkill but it may save you the cost of a replacement decoder.Since I always visually check the brushs when doing a install that is the perfect time to shorten the springs.As for switching the copper strips top to bottom that is excellent advice.
I have at various times bought locos swith dead motors I save the springs ,brushes and anything else I may have a use for.Replacing the top strip with a spare bottom strip makes hard wiring easier by providing two tabs to solder the wires to.
I have 6 Athearn BB SD40-2 frames with Cary E7 bodies and at slip the motors only draw a little over 850 ma., any one amp decoder should work fine on a normal Athearn BB. I’m using Digitrax DH126 decoders in my Athearn/Cary E7s and I’ve never had a problem.
The Athearn/Cary weighs 2.3 pounds and on my 3½% grades two locomotives draw a total of 1.55 amps towing ten 6+ ounce passenger cars. Measurements were made using a Fluke 78 Multimeter.
The worst problem using an older motor is not keeping the commutator clean, excessive arcing at the brushes causes voltage spikes that can ding a decoder. Placing a 18 to 20 volt MOV (metal oxide varistor) or a pair of 18 volt 3 watt Zener diodes back to back across the motor wires will clamp the spiking, about 40¢ each at any electronics parts house.
Reducing the spring pressure of the brushes against commutator will increase the possibility of arcing. Keep the commutator clean and you won’t have near as many problems. I only need clean up my motors about every 100 hours of operation. If you see major arcing at the brush c
The cutting of the springs probably has little to do with current draw. The biggest factors here are voltage, load: ie torque requirement and magnetic flux. The brushes could act like a brake if the pressure was to high. However you would feel it if you rotate the flywheels.
There are a few misconceptions about the current you need to be able to sustain with the decoder. The real issue is power, VI. When the voltage spikes, it draws more current. This doubly hits the decoder. The stall current that is critical is the level at the maximum voltage of the supply. To increase the voltage above that some it has to be coming from the supply. (Shorts are a little different and we really don’t size the decoder for shorts.) The stall current for the round “jet” motor is around 3.2 amps at 16 volts. Using Olhms law, That would be 2.4 amps at 12 volts. The later rectangular motors reduced the stall current to like 2.2 amps at 16 volts. Or 1.7 amps at 12 volts. For a DCC power supply the critical values are between these two numbers.
There are a couple of issues to consider. An engine that is fully loaded, such that the wheels just start to spin at max power is likely drawing close to the stall current. If the stall current is 2.0, then it easily is drawing 1.6 amps.
The second issue is that at start, every motor draws its stall current for the voltage for a very small amount of time. As soon as the rotor gets moving, the level drops back. So for micro seconds, the motor is drawing stall current through the decoder. For DCC that is the current for like 14 volts.
The great mystery is how much current can a decoder take before the dreaded smoke occurs. And for what duration. Earlier vintage decoders had more capacity. Very few engines released today have a stall current greater than one amp. Thus for todays engines, one amp is en
Hello modelmaker51,
You may feel that my insulating and isolating are “overkill” but having a background in robotics for the entertainment industry I’ve learned that physical barriers are far superior to an “air-gap” for containing those pesky electrons.
For a few pennies, I have put in place redundant systems that will prevent (no such thing in electronics as “insured”) the loss of a component that costs hundreds of times that of the actual amount of materials used.
“An ounce of prevention is worth a pound of cure.”
I agree that you may have not experienced component failure with your method. I’m not arguing that. But once the “magic blue smoke” has left the component (a decoder in this situation) it’s impossible to put it back without replacing it entirely.
Nothing is “idiot proof, just idiot resistant.”
Hope this helps.
I have been using this kit from PPW. The lead cradle goes in place of the Athearn mount and has a radius to match a can motor. I have installed this into 6 BBs and Atlas yellow boxes and am very happy with the results. Much better low end response and the same top speed.
I have also used the PPW motors and remotoring kits in several Blue Box DC improvements.