Help on removing trucks from this locomotive


S

shortwrench

Well-Known Member
I picked up this F7A at the Amherst train show. It's purpose is a guinea pig for my learning how to repaint a loco. Knew it didn't run but that's ok.
Would also like to get it running to gain experience in loco repair.

Can't figure out how to remove the trucks. The bottom of the fuel tank has the number 42005. Doesn't look like anything on the Bachmann site.
Anyone recognize the manufacturer and shed light on truck removal?

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The worm cover is horse shoe shaped with the ends clipping over the gearset. I used a small flat blade screwdriver to pry one side out and up slightly and then the other side. Be careful, they are slippery Delrin and can travel a great distance and hide well! :)
 
It looks to me like the universal on the forward truck is disconnected from the matching part on the motor. While the video is good, it looks like you are missing the metal contact strip that goes over the top of the motor and tucks in beneath the L-shaped pieces on each truck. No worries! You have the copper contact piece that clips to the top of the motor. Simply solder a flexible wire (say #24 AWG) to the copper strip, and an end to each of the L-shaped pieces on each truck. Unless the motor is burned out, it should put you in business. Be sure to use DC power ONLY! This is not equipped for DCC.
 
Thanks for all the replies.

Dave-nice video and a big help.

I ended up using a #11 Xacto knife to get the gear tower housings off and didn't lose any.

Yes, the forward universal is disconnected and got that way when I moved the motor up off
the lower spring mount when I was trying to figure out how to disassemble the drive. I had
removed the top contact piece after I got the shell off.

The end bearings on the worm shafts were all gummed up. The motor commutator needed
cleaning and the bearings needed lube.

Is there any way to isolate the motor from the frame so I can add a DCC decoder?

Not sure I want to use this loco as sacrificial unit to learn how to paint.
 
shortwrench said:
Thanks for all the replies.

Dave-nice video and a big help.

I ended up using a #11 Xacto knife to get the gear tower housings off and didn't lose any.

Yes, the forward universal is disconnected and got that way when I moved the motor up off
the lower spring mount when I was trying to figure out how to disassemble the drive. I had
removed the top contact piece after I got the shell off.

The end bearings on the worm shafts were all gummed up. The motor commutator needed
cleaning and the bearings needed lube.

Is there any way to isolate the motor from the frame so I can add a DCC decoder?

Not sure I want to use this loco as sacrificial unit to learn how to paint.
Click to expand...
To insulate the motor you have to pry it loose from the chassis, and remove the metal contact that lies between the bottom of the motor and the frame. If the rubber prongs that fit into the holes in the chassis won't go back in, or to insure insulation, use bath and tub calk to "glue" the motor to the frame. It would be best to check lack of continuity between the motor and the frame with an ohm meter. For a decoder I'd go with a Soundtraxx Tsunami diesel decoder that is rated for at least 1 amp full stall...maybe 2 amp. One thing about these old Athearn blue box F-7's, they will pull! Great if you have a large layout and/or one with a steep grade!
 
shortwrench said:
Is there any way to isolate the motor from the frame so I can add a DCC decoder?
Click to expand...
That old iron ring motor can draw over 2 amps. Some decoders meant for G or O scale stuff might have the capacity to run it, but not many. Make sure you confirm the amp rating for any decoder you use with it.

As for isolating it, remove the motor, bend the two tabs on the bottom metal strip on the motor up and away from the frame, and put a strip of kaptan or electrical tape over that part of the frame. Wire the lower motor connection to the headlight ground lug, or drill and tap and screw in and attach a wire to it.
 
After completely going through loco, the F7 is back together and running. The biggest problem
was the worm gear bearings were bound up on the worm shaft (both trucks). Dirty wheels, dirty
commutator, lack of lubrication of the motor bearings, and general cleaning were other factors
affecting the loco's ability to run.

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It certainly is a nice looking loco and will not be subjected to repainting. A DCC decoder will be installed. As stated,
it pulls great. Not bad for $10 at the train show.

Thanks to all for your help.
 
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