The problem with the Bachmann HO 1870's 4-4-0 is not in the motor. The performance problem is the lack of reliable electrical pickup. The stock locomotive electrical pickup only has pickup on one side of each tender truck and one set of drivers. This does not give good running performance. I have found that all wheel tender pickup is the key to good small steam performance. The tender provides a flexible platform for wheel contact and wipers that contact the wheels directly gives excellent performance.
My first attempt was using 31-1/2" diameter IHC wheels with wipers. This was the method I used on my old time IHC 4-4-0's. Performance was excellent but the wheels were just a little too large.
Here is the tender with Kadee 28" diameter wheels. They fit the short tender better visually. This article discusses putting wipers and those wheels on the tender and eliminating the pizza cutter stock wheels.
Kadee Centering Springs for #5 couplers
Kadee 28" Wheelsets
NWSL has 28" wheels with short axles.
#00-90 x 3/16 long round head screws
.002 brass shim stock
Flexible wire
1/32 Thick PCB
The truck sideframes will be needed to be reamed with a truck reamer. I got mine at Micro-Mark.
Testing the trucks for electrical pickup will require an electrical tester. I use an automotive circuit tester. Ace hardware has one for $2.99.
Also used:
A small soldering iron, Rosin flux and electrical solder
#00-90 Tap and drill set
ACC
Needle nosed pliers
Screwdrivers
Motor Tool and Brass wire Brush
#400 grit sandper
Fine cut needle files
Vernier Calipers
A power pack and test track
Carefully spread the side frame apart and insert the reamer and spin it to make the journal deeper. Do both sides.
The finish on the Kadee 28" wheelset doesn't conduct electricity so it is removed with a brass wire brush in a motor tool.
I originally burnished them after shortening the axles to fit, utilizing the original frames.
Now I would put them in a regular HO truck frame that accommodates the wheelsets without reaming the journals and burnish them.
I melted one of the Bachmann journals by using too much force. It is better melting a "mule".
Burnish the wheel treads and the lip on the back of the flange. Make sure they are smooth.
Shorten the axles by removing the points of the axles by drawing the points across #400 grit sandpaper.
Shorten the axles equally on both sides until they are about .910 wide. Test them in the frames. The should spin freely.
If they don't remove the axle end a small bit at a time. The axles should be between .905 and .910.
Ream a little if they still won't spin at .905.
The stock Bachmann "pizza cutter" wheel set at the bottom, the modified Kadee in the middle and the stock Kadee at the top.
The Kadee axle has to be blunted because of the smaller diameter of the Bachmann axle and the limited "meat" in the truck sideframe journal. The wheelset rides on the taper.
Originally I was going to use the large flat on the wheel. There was a casting nib on the inside of the wheelset at the yellow arrow. I could not smoothly remove the nibs.
My contact surface was moved out to the back of the flange.
The back of the flange actually works better with the short wheelbased trucks.
The wings of the Kadee centering spring are spread out. One of the wings is larger, I found that making the wings symmetrical makes for easier tuning.
Grasp the wing in a pair of pliers with a portion above the jaws. With a fine file, filing toward the handle taper the wing.
The spring should be symmetrical.
Cut off the spring body at the bottom of the large hole. Drill a #60 tap drill hole through the spring body. Support it with a small piece of wood. I used a coffee stirrer.
Place the spring on the sideframe and drill and tap for a #00-90 screw.
Use the truck reamer to break the edge of the tapped hole to make the insertion of the screw easier.
Using a #55 drill open up the hole in the wiper to clear the screw.
Remove everything not shown from the bottom of the tender frame. Slide 3/16" wide x .002 thick brass strips under the tender contacts. Solder them as shown and ACC the strips to the frame when the solder has cooled.
Attach the wiper to the truck with a #00-90 x 3/16 long screw. The longer screw will allow the wiper to be pulled up off the wheelsets during tuning without taking the wiper off. This is a picture from the 2006 article. The wires are from the original idea.
Bend the wiper wings to allow the wheels to turn "freely". The wheels should roll along the track with light finger pressure on truck while it is pushed along the track.
Test the electrical pickup with the automotive tester while rolling the truck along the track. Test one wheel at a time.
Place the truck on the frame with the motor as a weight. The wheels should turn as the tender is pushed along.
Take the wiper off and do the wiper on the opposite side.
After both wipers are individually "tuned" test that they will roll together.
This modification will make the HO Bachmann 1870's 4-4-0 crawl through plastic frogs of both Atlas and Bachmann EZ-Track. It even goes through an unpowered Atlas #10.
This modification can be accomplished without having to dis-assemble the locomotive.
(Click Images to Enlarge)
Cut the original wipers in half and bend them as shown. Slide them under the truck pickups. Cut about a 1/16" off of the wiper blade. There is interference at the wiper, nip off the piece.
DCC is easy. Use a small N/Z scale decoder. I used a Digitrax DN135D. Just hook up the red and black wires to the tender lugs and the orange and grey to the motor. Watch the distance between the orange wire and the tender pickup.
Cut a piece of PCB to cover the bottom of the loco. 1/16" is shown. That won't work, D-oh!!, the tender connector wires will short out on turnouts. I replaced it with 1/32" thick and that worked. If you can't find PCB that thin an alternate is brass shim stock glued to styrene like the strips on the tender.
The electrical board has to be relieved to clear the gear.
Cut a KD #5 spring in half to make a wiper and solder them to the PCB.
Those are reduced flanges accomplished by chucking the drivers in an electric drill.
Solder flexible wires to the pickup strips and the locomotive. The wires could be made to look like water hoses.
Make sure the PCB is electrically separated into halves. Remove the copper clad around the screw, D-oh!!!
Reduced Flanges in the Blue Box
The new locomotives in the "Blue Box" have flanges that will negotiate Micro-Engineering Code 55 track.
Cut the tender deck for clearance and run the wires away from the motor armature.
