The very item which makes a trolley model unique can also
be the model’s undoing. You place a trolley model on the track, place the trolley pole (pan) on the wire, turn on the power, and nothing happens.
The over all problem may be non-conductive oxidation or dirt on the wire, trolley pole slider or wheel, track, or wheels. OR, the model no longer runs due to an electrical short
circuit.
If you routine for getting the model to operate due to non-conductive oxidation or dirt does not work, STOP trying to pass electrical current through the model!
When the problem is due to an electrical short circuit, the
amperage of the power supply can be passing through the entire wiring of the
model including the trolley pole.
Resistance in an electrical circuit causes the conversion
of the electrical energy into heat energy (heat). The heat can cause problems.
Soldered joints in models or wiring will un-solder causing wires to come apart
and brass models to deform and come apart. Wire, which is metal in a thin,
dawn-out form, will not only deform but will lose other physical properties.
The reason for this post is the affect of an electrical short
circuit has on the trolley pole! When the total amperage of
the power supply goes through the trolley pole; the wire used for the trolley
pole, the material used for the trolley shoe or wheel and trolley base, the
springs, and the screw and/or material used to hold the trolley pole to the
roof of the model will be affected.
The most common affect I’ve seem is the deformation of
the springs. First the springs will become hot and then glow until the electric
current is turned off. After this the springs are soft and stretched-out. The
springs will no longer hold the trolley pole up to the trolley wire. The only
way to get the trolley pole to work again is to replace the springs.
Recently I obtained a streetcar which would not run when
placed on my test track. The test track is a 36” long straight piece of track
with overhead wire. An old power supply is used to power the test track. To see
the amount of current used both a voltmeter and ammeter are part of the
electrical circuit.
This photo is the power supply installed at 1 end of the test track.
From left to right - a brass rod line side pole with the positive power supply attached with an alligator clip.
At the bottom right is the negative power lead attached to the track.
The black electrical panel part in the center contains the 2 meters.
The black wire coming out of the panel is the positive and negative power leads with alligator clips.
The use of the toggle switch in the bottom center of the panel is unknown.
The toggle switch at the bottom right of the panel controls the direction.
At the right is the small but useful power supply.
The voltmeter and ammeter are an important part of the
circuit. You can tell immediately the electrical “condition” of the model or
whatever is connected to the wire leads of the power supply.
Recently to test a newly acquired non-operating model (without disassembling
the model or placing it on the test track) the positive (red) lead was
connected to the trolley pole and the negative (black) lead to the power truck.
The model didn’t run.
Next, the trolley pole was removed (unscrewed) from the
model. The pole unscrewed unevenly from the model (This turns out to be an
interesting observation.). The positive lead was attached to the 2-56 screw
sticking out of the model’s roof. The model still didn’t run.
I knew there was an electrical short circuit in the
model. Without knowing exactly where the short was, I decided to replace the
“wiring” from the inside of the trolley base to the motor lead outside the
model on the floor exterior. This was estimated to be a 30 minute task.
Without going into too much of a discussion, the model
was wired-up so the power truck could be easily electrically disconnected from
the model. At the same time the negative ground was brought-up into the model.
This later part was done for the future installation of interior lighting in
the model.
Back to my interesting observation of the difficult
trolley pole removal from the model – it’s the reason for this post. The
correct trolley pole base for the model is a 4 or 2 spring vertical. This was
on the model when I got it. Observation of the trolley pole base disclosed the vertical
part of the base was curved.
The springs were removed to be able to better see the
base and perform corrective actions. The vertical part of the base was deformed
when the full amount of electrical current of the power supply went through the
trolley pole. The piece of metal heated up enough to become soft. The action of
the springs was strong enough to cause the heated piece of metal to take on an
“S” shape.
The part of base which was deformed was a lost wax
casting. Small protrusions were filed off. Then the trolley base was placed in
a vice to apply enough pressure to straighten the metal casting.
The springs were replaced and the trolley pole moved up
and down without any problems. To blacken the part of the trolley pole which
had deformed, the lower portion of the trolley pole was dipped into Neolube #2.
At the same time this will improved the electrical connection where the 2-56
screw, screws into the trolley base. Allow the Neolube to dry first before
attaching the trolley pole to the model.
The bottom line of this post is when 1st
testing a model which you have never seen run, test it with a power supply
having both amp and volt meters. If there is a short, high amperage draw for a
comparable model, immediately turn off the power to avoid any damage to the
electrical circuit.
If a model with an electrical short circuit is allowed to
have high amperage go through the model for an appreciable length of time,
inspect the model including the trolley pole for damage. The trolley pole may
have been damaged in a way which alters the geometry of the shoe or slider and
the trolley wire.
Trolley poles are expensive. But at the same time they are the part of the model which sets it apart from other railway models.
Cheers,
Ed
