July 11, 2011 - Update

July 11, 2011

The hot days of summer are here but there are many cool shaded spots at MCC such as near the new truss bridge shown here (click thumbnail to enlarge).  Recent construction activities  are described below.

Sidings at Whitaker​:  Randy is adding three sidings (a mini yard) at Whitaker on top of the big hill.   The sidings are on fill excavated (mostly by hand) from the nearby cut.

 

This photo was taken from the west side of the loop on the hill looking south.  The left track is the main track.  The next track to the right is the Whitaker siding that is in operation.    The right three tracks are the new sidings.

This photo was taken from the switches for the three new sidings looking southeast.    The plan appears to be to connect the left most of the three sidings first.  

This is further along the left most of the three new sidings.  The two switches are for the south end of the other two new sidings.   

This last photo taken from the switches in the previous photo is looking east.   The switch on the main line is already in place.   This wonderfully shaded area will be a great place for a summer picnic.

Signals: Mill Creek Central is a single track railroad with passing sidings located about every 600 feet.   The single track sections (called blocks) have two-way traffic so a signal system is required to control access to each block.    The new lower loop track required the addition of two new blocks.  The buried wiring for the new blocks was completed last week and the installation of the new signals is underway.   This construction provides a good excuse for the following short description of the signals.


This photo taken from the Daffodil siding looking north into the NORATS block shows the three signal components required at each end of a block: the Signal Stand with lights, the yellow Block Take momentary switch stand on the right and the green Block Release momentary switch stand on the left.  The gray box on the ground to the right of the signal stand contains the low voltage transformer and the power module. One power module is required per block; more than one block can be powered from a transformer.  

The lights in this case are green indicating that the block is idle.  Before entering the idle block the train engineer must operate the yellow block take momentary switch.   If the take operation is successful the lights will change to amber   

This photo shows the amber lights after the block has been taken from this end.  The train can now enter the block.  The engineer must operate the green block release momentary switch when the other end of the block is reached to return the block to the idle state.  The momentary switches are located on the right side of the track .  Note the green momentary  switch is on the left in this photo but is to be used only by trains traveling toward the photographer which puts it on the right side of the engineer.  An engineer should not enter a block that has an amber signal obtained by another train ahead of the engineer ----- the engineer of that train will release the bock when he gets to the other end and any following train could be in the block when the block is given to another train entering the block from the far end.      

This photo shows the red signal lights indicating that a train is coming from the far end.   The yellow momentary take switch has no effect when the signal lights are red.    

This is Lora (the signals engineer) installing the power box for the two new blocks.  The box contains a 115 volt to ~ 9 volt transformer and a power module for each of the two new blocks.    

These modules Lora designed and built are solid state.  The module on the left in the photo (it looks to be about 1" X 2") is the power module (one per block) that is housed in the power box with the transformer.  The signal module (about 2" X 2") (one per signal housed in the bottom of the signal stand) is on the right.  The beauty of this system is that the everything interconnects with 2-wire cables.  That is: 2 wires between each momentary switch and the associated signal module and 2 wires (the power wires) between the signal modules.  The 2 wires from the power module can connect into (in parallel with) the power wires between the signal modules at either end or anywhere between. The control signals between the signal modules are carried over the power wires.   

A neat feature of this design is that additional signal stands, modules and momentary switches can be added in situations where there is a third (or forth) entry/exit point to/from a block.   The 2 wires from that third module are merely wired in parallel to the 2 power wires connecting the other two modules.     

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