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This is how I made the ground
signals work. The plastic cased relay is attached to the
ground signal by a piece of 6mm brass, which has a slot
cut up it. The ground signal is soldered to the brass, an
8BA screw attaches the relay to the bottom. By drilling
holes through the case, a screwdriver can be inserted. A
dropper goes from the arm to the relay armature, a pair
of tweezers is poked through another hole to insert the
wire. The advantage is that the signal can be assembled
on the workbench, disassembled, inserted into a 6mm hole
in the baseboard, then reconnected underneath. |
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This is an assembled ground
signal in situ on the layout. The extended sleeper has a
C shaped hole that fits around the spindle. Note the C & L plastic chairs have
yet to be painted in this shot, nor has the ballast been
applied. The balance weight is not connected to the
armature. This is because it only moves slightly, and
would therefore not be easily seen. And how many working
ground signals have you seen?
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What about the bouncing
signals? Standard Great western lower quadrant signals
bounced, by nature of the stretch in the wire making them
over pull on the downward stroke, then on their return to
danger, there was a spring loaded stop. A worn spring
would give that characterstic arm at on but pointing
slightly upwards. Here is
a view of a standard signal mechanism. A standard small
relay is stripped down, the action of the armature
against the large pendulum slows down the jerky action of
the relay. Approximate size of the pendulum is 4". A
flexible stop is made, in this case, of tinplate, with
some draught strip as an extra bounce. A simple 4mm ply
box surrounds the mechanism, the pendulum is pivoted on a
1/8" Ø rod, supported in the box. The whole
mechanism fits into a hole in the baseboard, so that it
can be assembled and adjusted on the bench before
installation.
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The mechanism for the up
bracket. Note the old TO3 transistors, used as extra mass
on the pendulums. The tortoise point motor is connected
to a standard 8 pin DIN plug, in case of problems, the
motor can be tested and replaced without a soldering iron
in sight. |
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A difficult shot, showing the
standard arrangement for the signals. A paxolin base is
drilled for pins that locate the signal onto its
mechanism. The top, being copperclad, can have ladders
soldered to it. Underneath, the push rod to the arm is
inside the 1/8 internal diameter tube. Note that the pushrod is not connected to
the counterweight. This would need extra bends in the
wire and is a source of problems. Better off leaving the
firmly fixed. The eye is drawn to the signal arm, not the
actions at the base.
At the bottom is the weight that
the top edge of the pendulum contacts with. The result is
a signal mechanism that can be assembled on the bench,
installed in the layout, and removed easily for
maintenance and transport.
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