Several of Travel Town's locomotives are "goats" like this one. The term "goat" is rail jargon,
meaning "switch engine," or a locomotive employed to move other locomotives or cars around the
repair shop and switch yard. Switch yards are divided into several parts: receiving yard, separating
yard, classification yard, and departure yard. In these areas train cars are split up (or "cut" from the train) and regrouped for their continuing journey to their final destination. Additionally, switch yards contain maintenance and repair facilities. First, a train enters the receiving yard: where the
locomotive is disconnected and prepared for its next trip, the caboose is cut off, and the switch
engine usually takes over. In the next part of the switch yard, the train cars are "cut" and separated according to their destination or the product they are carrying.

   Cars carrying the same product or going to the same district are placed on the same track within
the switch yard's complex network of parallel and interconnecting railroad tracks. From the separating yard, cargos are classified even more precisely and cars are sorted again onto tracks with cars
carrying the same goods. New trains are assembled in the departure yard by coupling together cars
from different classification tracks. Finally, the switch engine is disengaged and the new train is
coupled to a regular road engine for continuation of its trip. During the early portion of its career,
#4439 worked as a "goat" in the U.P. switch yard in Cheyenne, Wyoming. Later #4439 served on
the Los Angeles Harbor Belt line, until her operation ended at the order of the Air Pollution Control
Board in 1957. U.P. #4439 was the last steam locomotive to have operated in both the Harbor
and the greater Los Angeles areas