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Lisa

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Blog Comments posted by Lisa

    Steam_Julie

    Posted

    What causes the slackening of speed, whilst negotiating a curve is the flange on the wheel on the outside of the curve rail coming into contact with the inside face of said rail.

     

    That is why on the prototype the a check rail is place alongside the inner rail, to pull the wheelsets across to prevent the out wheel flange coming into contact with the rail edge.

     

    Lisa

    Ian Smith

    Posted

    Many passing loops on the GWR system that had bi-directional operation on one loop also had the option of switching out the signal box, when not required.

     

    This was controlled with a King lever, this allowed the the signaller to pull off both the Down and Up signals at the same time. Electrically the block instruments were also linked to bypass the switched out boxes instruments.

     

    There were special bell codes that the signaller in the box to be switched out used to both the boxes on both sides, which had to be recipricated before switch out. Before the switch out could be started both sections and the loop had to be unoccupied.

     

    Lisa

    Ian Smith

    Posted

    My comment relates to the Dummy which controls exit from the goods loop to the down main. This should be a yellow dummy. This has a yellow strip and shows a yellow aspect when ON and a green when OFF.

     

    This can be passed when the crossing to the connect to the goods loop and the down loop is set to allow trains to shunt into the goods shed or adjacent siding and Up or Down trains pass. This is called a Lock-in. The second point controlling access to the goods shed and middle would be controlled by an hand lever. Thus the signalman does not have to pull of the dummy when shunting is in progress in the yard, only when access to the Down loop is required.

     

    Many GWR lines had bi-directional signalling at such stations on the Up line, to allow through workings to pass whilst a Down freight trains was being shunted, with the brake van and several wagon in the down loop. These trains could be accepted by the signaller into the section provided the Up line was clear.

     

    Without the bi-directional signalling only Up trains can be accepted during a Lock-in situation. The latter is defined when the locomotive and part of the train are in the goods loop and sidings, with the points set to the Up loop with or without part of the train in the Down loop.

     

    If an Up train is fully in the Goods loop and sidings an Up or Down train can be accepted. I hope the above helps.

     

    I also think that the access points to the Back siding would be further along the loop to allow it to be shunted in Lock-in mode.

     

    Lisa

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