The letter codes make reference to the control
box - CH Compost Heap, HO Houchel (neighbours name) RS Romford
South Box. RS signals are manually controlled by a 12 lever frame
in the signal box.
|After early trials with treadle switches
the decision was made to revert back to using track
circuiting as trialled in the tunnel. Originally I used
connector blocks to connect all the components together
but this was a bit messy.
Left - One
of the original control box under the bridge. These
components were removed and replaced with our new modular
|Above - Our new boards
which we are using on all our automatic signals. The
relay at the bottom right is to control the points and
crossing set up.
Left - The same box
with the new relay boards in place. By using individual
boards for each section, if one fails it can be easily
Track sectioning. Previously we used paxolin
board to hold the rails but we have found it was quite hard to
keep the rails inline. As an alternative we have used delrin
blocks which has a groove machined in the top edge which holds
the rails in line.
Below right - Having cleaned up and greased a
fishplates to allow a bit more thermal movement, we found that
the grease stopped the flow of electricity between the two rails.
To extend the circuit we have to loop around the join, just as
they do on the real thing.
While using 12v for the track circuits we have
come across a few problems.
1st few trains tend not to give good
contact - presumably this is down to rust.
Wet steel rail track can hold the circuit
open. For some reason the steel seems to let the
electricity carry better betweent the rails. Presumably
the current runs down the track screws and through the
sleeper. It doesn't let enough through to trip a circuit
but it does let enough through to hold a relay open once
a train has set it. We have cured this by adding a load
between the switched live rail and neutral.