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Passing Contact Switch : A changeover switch which only connects momentarily as the switch is thrown. Used for solenoid type turnout motors.
Plastikard : A trade name, for a range of thin polystyrene sheet, which is ideally suited for modelling. Plasticard is manufactured by Slaters Ltd and supplied is in a range of thickness ( 0.005" to 0.060"). Similar products are available from several suppliers.
Points : Another word for turnouts.
Pre-Group : In the United Kingdom this is the period up to the 'Grouping' of the railway companies in 1923 to form 'the Big Four' the GWR, LNER, LMS and Great Western Railway.
Push Pull : One of my favourite types of train where the train's carriages are kept permanently coupled to the locomotive which pulls them in one direction then pushes them in the other. On most layouts the locomotive would be of the tank variety.

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