Union Pacific Light Challenger

Union Pacific Fetter Challengers
Technical specifications
Designer(s)	Arthur H. Fetter
Serial number(s)	68745–68759, 68924–68948
Manufacturer(s)	American Locomotive Company
Build date	1936-1937
Total produced	40
Classification	CSA-1, CSA-2
Rail gauge	4 ft 8+1⁄2 in (1,435 mm) standard gauge
Cylinders	Four
Boiler pressure	255 lbf/in2 (1.76 MPa)
Bore stroke	22 in × 32 in (559 mm × 813 mm)
Firegrate area	108.25 sq ft (10 m2)
Fuel type	Coal, oil
Heating area	2,162 sq ft (200.9 m2)
Performance figures
Maximum speed	70 mph (110 km/h)
Tractive effort	97,305 lbf (432.83 kN)
Factor of adhesion	4.11
Service information
Running numbers	3900–3914, 3915–3939. Renumbered as 3800–3814, 3815–3839
Disposition details
Preserved	None were preserved
Disposition	All Scrapped

The Union Pacific Fetter Challengers were a class of 4-6-6-4 "Challenger" Locomotives built for the Union Pacific Railroad.

History

Inception

In the 1930s, the Union Pacific Railroad needed a new class of locomotives to tackle the mountain passes of Sherman Hill and the Wasatch Mountains in Utah. Their largest Non-Articulated Locomotives at that time, the 9000 Class 4-12-2s, were tried out but couldn't handle the tight curves of the route due to their exceptionally long rigid frames.

Construction

Arthur H. Fetter went to the drawing board to create a new steam locomotive by splitting the 12 driving wheel frame in half and have it joined by a hinge-pin in the middle so the engine could bend around tight curves, enter the Union Pacific's Fetter Challengers. They were classified as "CSA-1" and "CSA-2". All members were built by The American Locomotive Company (ALCO).

Disposition

Sadly, all 40 were retired from active service when the Union Pacific Railroad began to dieselize their lines. Although Union Pacific's 4664 Class No. 3977 and 3985 were preserved, all 40 of the Fetter Challengers were scrapped.

Trivia

• Some chose to call them Light Challengers after the heavy challengers were constructed.

Stock list

Number	Photograph	Build date	Notes
3800		1936
3801		1936
3802		1936
3803		1936
3804		1936
3805		1936
3806		1936
3807		1936
3808		1936
3809		1936
3810		1936	It was originally numbered #3910, but then in 1949 it was renumbered to #3710 because of a coal strike.
3811		1936
3812		1936
3813		1936
3814		1936
3815		1937
3816		1937
3817		1937
3818		1937
3819		1937
3820		1937
3821		1937
3822		1937
3823		1937
3824		1937
3825		1937
3826		1937
3827		1937
3828		1937
3829		1937
3830		1937
3831		1937
3832		1937
3833		1937
3834		1937
3835		1937
3836		1937
3837		1937
3838		1937
3839		1937

A sound recording of 3827’s whistle.

List of Union Pacific Challenger Locomotives
CSA-1:	3900 (3800) • 3901 (3801) • 3902 (3802) • 3903 (3803) • 3904 (3804) • 3805 • 3906 (3806) • 3807 • 3808 • 3909 (3809) • 3910 (3810) • 3911 (3811) • 3912 (3812) • 3913 (3813) • 3914 (3814)
CSA-2:	3815 • 3816 • 3817 • 3918 (3818) • 3819 • 3820 • 3821 • 3822 • 3823 • 3822 • 3823 • 3824 • 3825 • 3826 • 3827 • 3828 • 3829 • 3830 • 3831 • 3832 • 3833 • 3834 • 3835 • 3836 • 3837 • 3838 • 3839
4664-3:	3950 • 3951 • 3952 • 3953 • 3954 • 3955 • 3956 • 3957 • 3958 • 3959 • 3960 • 3961 • 3962 • 3963 • 3964 • 3965 • 3966 • 3967 • 3968 • 3969
4664-4:	3975 • 3976 • 3977 • 3978 • 3979 • 3980 • 3981 • 3982 • 3983 • 3984 • 3985 • 3986 • 3987 • 3988 • 3989 • 3990 • 3991 • 3992 • 3993 • 3994 • 3995 • 3996 • 3997 • 3998 • 3999
4664-5:	3730 • 3731 • 3732 • 3733 • 3734 • 3735 • 3736 • 3737 • 3738 • 3939 • 3740 • 3741 • 3742 • 3743 • 3744 • 3745 • 3746 • 3747 • 3748 • 3749
Clinchfield Railroad:	Locomotive Type
Extinct:	Fetter Challengers
Excursion Star:	3967 • 3985
Preserved:	3977 • 3985