American Flyer 312 Tender(SIT) Electrical Problem

Classic Toy Trains Forum
1

Back last December, I took this 312 tender apart for total overhaul, rewiring and smoke element replacement. I made a wiring diagram of all the wires before unsoldering them. I completed the overhaul(and replaced all wiring) and the smoke unit and motor driven bellows worked just fine. I set the tender aside as i needed to also overhaul the locomotive. Three months went by before I completed the engine overhaul. To my great surprise, the smoke unit and bellows motor no longer works.

The problem appears to be in the on/off lever switch that contols the smoke unit. The switch contact rivet is feed by a power lead that runs from the rear truck mounting rivet to a solder lug under the switch contact rivet. The actual switch lever has two wires soldered to a lug under the lever mounting rivet. One of these wires goes to a motor brush terminal and the other to the right hand terminal on the top of the smoke unit box. For some reason, when the switch is placed in the on position(lever contacts the switch contact rivet) no power flows thru the switch to the motor brush connection and smoke box terminal connection.

I have removed these wires, cleaned the lugs, and replaced the wiring a second time…did not fix the problem. I checked the two tender leads that plug into the loco terminal and they provide electricity to the loco when the tender is on track with power on. On of these plug/jack leads also solders to the head of the rear truck mounting rivet. To me, this means the switch contact rivet is definetely receiving power since its lead also solders to the rear truck mounting rivet.

I see no defects in the switch, the rivets are tight, insulators are in place.

I would appreciate advice on how to toubleshoot this perplexing problem.

2

The power flows from one truck pickup, through the switch, into one motor brush, out the other brush into one wire of the field coil, out the other field coil wire and to the other truck pickup to complete the circuit. The smoke unit also needs to get a power and ground connection. Disconnect the tender from the loco and check it independently. If you have a voltmeter, check for track power at both truck rivets where the wires are soldered. Check for power across the smoke unit. You should get power there at least. No power is a wiring or truck pickup issue. Power to smoke unit and no motor is a motor issue.

Larry

3

Larry,

I starting working on this tender this past Saturday afternoon. Put it on the track and did not work. I then took it to the bench and examined it carefully. That is when i discovered that the top bush spring was not contacting its brush . It must have come disengaged when I replaced the wire lead to it last week. I put the spring back in place and applied power…the motor runs great and it smokes just fine.

Thanks for your help.

4

http://americanflyerexpress.com/American-Flyer-Express/American-Flyer-Express-Pages/American-Flyer-Steam-and-Diesel-Factory-Reference-Manuals/Steam-and-Diesel-Factory-Service-Manual-Books/Gilbert-American-Flyer-Steam-Locomotives-2nd-Edition-765-pix-05.png

Go here for a picture of the wiring diagram for a Hudson 322 SIT tender.

5

check the connection from the lever side to the rivet that connects to the rear truck rivet.