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1: Sergent HO scale
couplers function
like the prototype,
with a ball dropping
in place behind the
knuckle arm to lock
couplers closed.
Graphite lubrication
and careful removal
of casting flash
is vital to smooth
operation.
I have Sergent couplers on my whole fleet, but they are more
time-consuming to assemble and install than more traditional
couplers. Wherever possible, I buy the kit couplers, and I find
they tend to work better than the factory-assembled ones.
When I assemble the couplers, I inspect every casting and
remove even seemingly insignificant flash before assembling
anything. Just to be sure the ball pocket is clear on top, I usu-
ally stick the point of a hobby knife in there and spin it around a
couple of times. Sometimes there is flash in there that is difficult
to see. Next, I apply graphite to the working surfaces of the top
casting, the place the knuckle sits, the ball opening, and any sur-
face the knuckle will slide on or near.
With the top casting all graphited, I assemble the coupler. Once
assembled, I remove it from the jig and glue it together. I have
found the best way to glue them is to use as little as possible, so
little that it flows into the opening by capillary action. If there is
a drop or bead of glue when I am done, I have used too much.
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