Railroads relied on the high quality cast iron produced at Greenwood Works. Though hard and brittle, it could withstand great weight. Shipped to Freedom Iron Works, the parent plant twelve miles away, Greenwood Works’ cast iron was made into locomotive tires, railroad wheels and axles, and piston and pump rods. It performed so well that Enoch Lewis, the General Superintendent of the Pennsylvania Railroad, wrote to Col. John A. Wright, Greenwood’s owner, that the railroad had used Greenwood iron for various purposes for more than six years and believed it to be the best iron it could procure for its most difficult forgings. Work begun at Greenwood continued in the factories at Burnham, where pig iron became finished products such as locomotive tires, the metal rims surrounding the wheels. As molten iron ran from the furnace, it filled channels in the sandy floor of the casting shed, and because these connected castings resembled nursing piglets, they came to be called pig iron.