S scale 4-4-2 hums but don't go

[SOU_RY_modeler]

 

I just bought an American Flyer 4-4-2 (Reading Lines # 302) yesterday at a train show, I test ran it after I cleaned the tracks I got with it and it ran fine but today it went fine but after passing over 3 sections it stopped and just buzzed... Does anyone know what the problem is the headlight comes on and the reverser buzzes but it doesn't go... yesterday it ran and smoked fine with no troubles... I would appreciate any help I can get seeing as I'm this is my first S scale locomotive and im still trying to figure out how everything works (I am using A.C. Current).

[Sturgeon-Phish]

American Flyer reverse mechanism can be finicky. There are a few things you can do to fix it.

The reverse unit works by a solenoid pulling up on a ratchet and pawl sending current to a different set of contacts.Ideally every times it cycles to 0 volts the solenoid allows the ratchet and pawl to cycle.It is a forward, neutral reverse neutral operation.

Open the tender shell, it is held on with metal tabs or screws depending on the year and you will see the reversing mechanism sometimes called the e-unit.

Set the tender on the track or better yet is apply power to the metal wheels, keep the tender in an upright position because the mechanism uses gravity to operate.

As you cycle the power there is a small cylinder with a copper band around it called the drum, that should rotate as you cycle the power.If it does not rotate there is a pawl and lever that often sticks.On the rear of the reverse mechanism toward the bottom is a small plate that moves up and down when the solenoid is energized.This can be cycled by hand.

The sticking pawl is fixable.First try cleaning it, then lubing it cycling the reverse unit by hand.CRC-5-56 or similar contact cleaner and a flux brush will do a good job of cleaning.If still sticking make sure there is not a burr or notch worn into the E-unit frame where the little brass “L” shaped piece makes contact, if there is use a small file to smooth the edge.Sometimes as a last resort, ever so gently bend the brass “L” shaped part so less surface area is coming in contact with the e-unit frame.

Once the e-unit is freely cycling, and it still just hums, then the current is not getting to the loco.Look at the strips of copper fingers on the e-unit where they contact the drum.It should be a sliding contact configuration.All four fingers must make contact with the drum.These often wear down and can be replaced.From there on out it is wire conductors and just do a continuity check for a break in the wires to the jack panel.

I hope this helps

Jim

 

 

 

[richhotrain]

Unless you are a purist and want to retain the original reversing unit, do what I did and replace it with a Dallee Electronics reversing unit.

http://www.dallee.com/E_Units.html

Rich

[Sturgeon-Phish]

A quick and dirty check if the e-unit is just sticking is to tap the tender as it sits on the track and hums.  Often if it is just sticking the tap will free the pawl and allow the drum to cycle 

Jim