Class 4000 “Big Boy”
The steep grades with inclines of up to 1.77 % on
the route between Ogden, Utah and Cheyenne,
Wyoming created considerable operating expenses
for the Union Pacific at the end of the 1930s. Up to
4 steam locomotives had to be coupled together in
tandem in order to pull the heavy freight trains along
this mountainous stretch of track.
An order was therefore placed with the American
Locomotive Corporation for a steam locomotive
capable of hauling these 3,600 ton locomotives
on its own along this route. The result was the
class 4000, placed into service in 1941 and soon
known around the world by its nickname of “Big Boy”.
The performance and dimensions of this 4-8-8-4
locomotive left all previous motive power in the dust,
and the Big Boy is still the largest steam locomotive
in the world.
Specifications:
Total locomotive length: 40.51 m
/ 132 ft. 9-7/8’’
Tender length:
13.90 m
/ 45 ft. 6 in.
Total weight:
540 t
/ 594 tons
Power:
5,884 kW / 7,000 hp
Coal capacity:
25.4 t
/ 28 tons
Water capacity:
94.75 m
3
/ 25,000 gal.
Top speed:
112 km/h / 70 mph
Normal speed:
64 km/h
/ 40 mph
3
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