ballast
131ballast resistor — (BAL RES) A resistor constructed of a special type wire, the properties of which tend to increase or decrease the voltage in direct proportion to the heat of the wire …
132Track ballast — forms the trackbed upon which railroad ties (US) or railway sleepers (UK) are laid. It is packed between, below, and around the ties. It is used to facilitate drainage of water, to distribute the load from the railroad ties, and also to keep down …
