AN AMERICAN FLYER® REPAIR CLINIC
From Port Lines Hobbies
AN AMERICAN FLYER® REPAIR CLINIC
From Port Lines Hobbies
"Newbies" in particular are often intimidated by the AF mechanical reverse units....you shouldn't be; they are easy to maintain. Moreover, proper maintenance is a "MUST" if they are to function properly.
FOUR-POSITION
REVERSE UNITS:
DISASSEMBLY: The earliest units were 4-step (F-N-R-N) units, located in the
boiler of steam engines, or about in the center of a diesel chassis. That lever
that protrudes from it is not an "on-off" switch.... it is a
locking lever that prevents the e-unit from functioning through its 4 positions.
If you do not want the engine to reverse direction when power is cut, the
locking lever is pushed sideways while the engine is running forward.
Now, the engine will always go forward in the future, unless you
"unlock" it. Later
e-units were moved to the tender of steam engines, and the lever points downward
through the chassis.
Once you have access to the e-unit, disassembly is simple.
You will see two fiber "finger boards" on it. The 4 copper or bronze
"fingers" make contact with a rotating drum. These fingers do
wear out because they are the site of electrical contact; they get dirty, and
they will eventually burn holes right through the contact-spot on each finger.
They need to be replaced before they reach this condition! To remove them, each
finger board is held onto the e-unit by two tiny metal tabs, one on each end.
Use pliers to straighten these tabs (which are twisted); just twist them
straight, and then lift off the board. Leave the wires soldered to the old board
for now. Next, remove the second finger board in the same way.
You can now gently spread the two sides of the e-unit just
enough to pop the drum out....clean it well, with a little contact cleaner on a
tissue, or even with just some rubbing alcohol on a tissue. Before replacing it,
notice that inside the e-unit, there is a "flapper" at the bottom with
a brass pawl that sticks upward and out through a hole in the side of the
e-unit. Make sure it operates freely; clean the rivet connection on it, and the
pawl, of any grease. Then replace the drum.
RE-ASSEMBLY:
You will need a new pair of finger boards; these are readily available, and
inexpensive, but quality is critical....the length of the copper fingers
must be precisely right or they will not contact the rotating drum in the proper
place!
Before pressing the new finger boards onto the tabs, give
each of the 4 fingers a slight downward bend (maybe 20-degrees or so); this will
ensure that they make good contact with the rotating drum. Insert the
finger-boards onto the appropriate tabs, and use your pliers to twist those tabs
just enough to hold the boards firmly in place. Be careful.....don't twist too
far or they will break right off! Note that the upper fingers have
the fingers offset to the right. The lower fingers are centered. Don't
mix them up.
Now just move the wires from the old finger boards over to
the corresponding fingers of the new boards, and solder them in place. Be sure
there is no wire or solder contact between adjacent wires, either on the surface
of the finger board, or underneath.....that will create a short.
That's it! You've rebuilt and cleaned your AF reverse unit!
One
final tip: It is not too unusual if these 4-position units seem to
"stick" in one position because the drum won't rotate (assuming you
don't have it locked, as described above). This is usually the result of the
tiny brass pawl that sticks out through the side of the e-unit. When that pawl
is pushed upward to rotate the drum, it may fail to drop back downward again.
Correcting this is trial-and-error, but here are some tips:
(1) be sure you cleaned the rivet connection at its lower end with some
degreaser or contact cleaner, so that it rotates freely at that rivet.
(2) use a round, rat-tile file to smooth the top edge of the hole through which
the pawl extends. Over years of use, the pawl hitting that upper surface can
actually create an tiny "notch" in the sheet-metal edge, and the pawl
now gets hung-up in it. Running the file over that surface will often correct
the problem.
(3) With needle-tip pliers, give the tip of the pawl a slight twist, resulting
in less metal-to-metal contact when it is in the "up" position.
This needs to be done with care however, as you can break the pawl off, or bend
it in such a way that it won't spin the drum.
(4) Another trick that usually works....IF that pawl just refuses to drop back
down, it may be because the "flapper" at the bottom of the e-unit has
become magnetized, and it won't release from the solenoid coil bottom. Easy
solution----glue a small fiber washer to the bottom of the solenoid coil.
Now, the "flapper" cannot contact it.....it will still operate, but it
will drop again when current to the coil ceases!
TWO-POSITION
REVERSE UNITS:
Gilbert later introduced a cheaper 2-position reverse unit
(no neutral) that operated on an internal cam which was tipped back and forth by
a rod that was pushed upward against it and then dropped back downward by
gravity.
Servicing these e-units is a little trickier, although you rarely have to
disassemble them. If it doesn't seem to be functioning properly,
(a) give it a quick shot of degreaser, particularly aiming at the upper surface
of the cam, and also at the metal weight if the rod doesn't seem to want to move
up and down freely.
(b) Then give it a follow-up shot or two of contact cleaner. Allow a little time
to evaporate, and then apply power and see if it has improved its operation.
This will usually solve most problems with these 2-position units.....fingers in
these rarely wear out.
PARTS
AVAILABILITY & PRICES:
(a) Finger boards for 4-position e-units: $2.50 per pair
(upper and lower)
(b) Drums (not reproduced; limited availability): $15
(Note that
drums do not go bad unless a tooth gets chipped off the cog, or the plastic
surface melts due to a short and heat damage.)
(c) Complete replacement e-unit (original/rebuilt): $30.
(Specify boiler or tender version)
(d) Modern solid-state reverse unit: $45. (Excellent quality,
and easy replacement).
(e) Contact Cleaner: I recommend Radio Shack Tuner Cleaner.
It comes in a small spray-can. It is a bit expensive, but it lasts a long time,
as you don't need a lot of it....just very quick bursts. I prefer it because it
is non-flammable, and it totally evaporates leaving no residue. Many other
contact cleaners are flammable.....BEWARE!
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