truck and track
The most up-to-date subway trucks ride on tires, which provide fast acceleration and little noise or vibration.
runway
Metal or concrete track that is fixed to the invert on which the tires roll.
running rail
Regular railroad rail for the steel safety wheel to roll on in the event the tire deflates; it also receives the traction current from the return shoe.
guiding and current bar
Metal bar against which the guiding tire rolls; it also supplies the traction current.
inflated guiding tire
Tire mounted at right angles to the carrying tire; it rolls against the guiding bar to guide the truck.
inflated carrying tire
Nitrogen-filled tire that supports and conveys the car.
steel safety wheel
Auxiliary regular train wheel that comes in contact with the running rail in the event the tire deflates and during switching.
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