User Manual
  The Challenger type of locomotive would serve 
until the end of mainline steam service. They were 
assigned  to  railroads  across  the  nation  and  under 
all operating conditions gave a good accounting of 
themselves. Two examples escaped dismantling. UP 
3985 has been  restored and joins UP 4-8-4  844  as 
the only two steam locomotives operated by a class 
1 railroad today. The other, UP 3977, has been on 
display in North Platte, Nebraska since 1968 and has 
recently  been  refurbished  by  a  group  of  dedicated 
(Alco) finalized the design of what was to become 
one  of  the  most  widely  recognized  locomotives  in 
the world. In 1936,  the  first  group  of  locomotives 
with  the  4-6-6-4  wheel  arrangement  was  delivered 
to the Union Pacific Railroad. They were an imme
-
diate  success  and  their  roster  grew  to  number  105 
locomotives  on  the  Union  Pacific  alone.  This  new 
wheel  arrangement  was  given  the  name 
“CHAL-
LENGER”. While the origin of the name is unclear, 
it proved to be an apt moniker.
railfan volunteers.
  In  1936,  the  Union  Pacific  Railroad  and  Alco 
met  the  needs  of  increased  speeds  and  tractive 
effort  with  the  design  of  the  Challenger.  Today,  the 
Genesis
TM
 Challenger meets the needs of modelers 
and collectors by providing an HO scale model that 
captures all nuances of the prototype, taking model 
steam realism to the next level.










