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Union Pacific Steam Locomotives, 1915-1962

Part 15, OWRR&N 3800 to UP 3999

This page was last updated on December 2, 2015.

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ORR&N 2-8-8-2 -- 3 locomotives (compound)

1915 OWRR&N
Number
First
Number
Second
Number
Builder Builder
Number
Date
Built
Date
Vacated
Notes
OWRR&N 3800 ORR&N 450 OWRR&N 700 Baldwin 34016 Nov 1909 Sep 1928 1
OWRR&N 3801 ORR&N 451 OWRR&N 701 Baldwin 34017 Nov 1909 Oct 1928 2
OWRR&N 3802 ORR&N 452 OWRR&N 702 Baldwin 34018 Nov 1909 Nov 1928 3

Description:

CS Class: MC-1
Drive Wheel Diameter: 57 inches
Cylinders: 26&40x30
Maximum Tractive Effort: 94,880 pounds
Weight on Drivers: 394,150 pounds
Weight in Working Order (Engine Only): 425,900 pounds
Weight in Working Order (Engine and Tender): 599,181 pounds
Fuel: Oil

General Notes:

a. Mallet Compound (MC)
b. Built as ORR&N 450-452 in 1909; renumbered to OWRR&N 700-702 in 1911; renumbered to OWRR&N 3800-3802 in 1915-1916.
c. OWRR&N 3800 was equipped with a stoker in December 1917.
d. OWRR&N 3802 was equipped with a stoker in March 1918.
e. OWRR&N 3800-3802 were assigned to LaGrande, Oregon for service in the Blue Mountains.
f. See "Ocean Toads, 1909 Monster Mallets", by James L Ehernberger, The Streamliner, Volume 5, Number 2, pages 13-24

Notes:

1. OWRR&N 3800 was built as ORR&N 450 in 1909; to OWRR&N 700 in 1911; to OWRR&N 3800 in 1915; vacated in 1928
2. OWRR&N 3801 was built as ORR&N 451 in 1909; to OWRR&N 701 in 1911; to OWRR&N 3801 in 1915; vacated in 1928
3. OWRR&N 3802 was built as ORR&N 452 in 1909; to OWRR&N 702 in 1911; to OWRR&N 3802 in 1915; vacated in 1928
   

OWRR&N 2-8-8-0 -- 3 locomotives (compound)

OWRR&N
Number
Builder Builder
Number
Date
Built
Date Converted
To Simple
OWRR&N Number
As Simple
OWRR&N 3803 (1st) Brooks 63776 Mar 1923 Apr 1944 OWRR&N 3567
OWRR&N 3804 (1st) Brooks 63777 Mar 1923 Apr 1944 OWRR&N 3568
OWRR&N 3805 (1st) Brooks 63778 Mar 1923 Apr 1944 OWRR&N 3569

Description:

CS Class: MC-4
Cabside Class: MC-57
Drive Wheel Diameter: 57 inches (rebuilt to 59 inches in 1944)
Cylinders: 26&41x32 inches (rebuilt to 23&23x30 inches in 1944)
Maximum Tractive Effort: 103,000 pounds
Weight on Drivers: 464,000 pounds
Weight in Working Order (Engine Only): 494,500 pounds
Weight in Working Order (Engine and Tender): 712,600 pounds
Fuel: Oil (converted from coal)

General Notes:

a. Mallet Compound (MC)
b. Built as compound locomotives in 1923; rebuilt to simple locomotives in 1944 (including changing drivers from 57 inches to 59 inches) and renumbered to OWRR&N 3500 series
c. Built as coal burners; converted to oil burners before 1938
   

UP 4-6-6-4 -- 15 locomotives "Light Challengers"

1944 UP
Number
First
Number
Date To
3800 Series
Builder Builder
Number
Date
Built
1949-1950
UP Number
Date
Vacated
UP 3800 (2nd) UP 3900 Apr 1944 Schenectady 68745 Sep 1936   Aug 1957
UP 3801 (2nd) UP 3901 Apr 1944 Schenectady 68746 Sep 1936 UP 3701 Sep 1957
UP 3802 (2nd) UP 3902 Apr 1944 Schenectady 68747 Sep 1936 UP 3702 Dec 1958
UP 3803 (2nd) UP 3903 Apr 1944 Schenectady 68748 Sep 1936   May 1959
UP 3804 (2nd) UP 3904 Apr 1944 Schenectady 68749 Sep 1936 UP 3704 Jul 1959
UP 3805 (2nd) UP 3905 Apr 1944 Schenectady 68750 Sep 1936   Feb 1956
UP 3806 UP 3906 Apr 1944 Schenectady 68751 Sep 1936   Jul 1962
UP 3807 UP 3907 Apr 1944 Schenectady 68752 Sep 1936 UP 3707 Aug 1957
UP 3808 UP 3908 Apr 1944 Schenectady 68753 Sep 1936   Apr 1957
UP 3809 UP 3909 Apr 1944 Schenectady 68754 Sep 1936 UP 3709 Aug 1957
UP 3810 UP 3910 Apr 1944 Schenectady 68755 Sep 1936 UP 3710 Sep 1956
UP 3811 UP 3911 Apr 1944 Schenectady 68756 Sep 1936 UP 3711 Sep 1956
UP 3812 UP 3912 Apr 1944 Schenectady 68757 Sep 1936   Dec 1958
UP 3813 UP 3913 Apr 1944 Schenectady 68758 Sep 1936   Sep 1956
UP 3814 UP 3914 Apr 1944 Schenectady 68759 Sep 1936 UP 3714 Jun 1957

Description:

CS Class: CSA-1
Cabside Class: CSA-69
Drive Wheel Diameter: 69 inches
Cylinders: 22&22x32 inches
Maximum Tractive Effort: 97,400 pounds
Weight on Drivers: 386,000 pounds (as built) (in later years their weight-on-drivers varied between 399,660 pounds and 407,610 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine Only): 566,000 pounds (as built) (in later years their weight varied between 569,820 pounds and 590,550 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine and Tender): 876,000 pounds (as built) (varied between 892,420 pounds and 915,000 pounds depending on type of feedwater heater and weight of front engine))
Fuel: Oil (eight locomotives converted to coal, then back to oil)

General Notes:

a. Challenger Simple Articulated (CSA)
b. UP 3800-3814 were built as UP 3900-3914 in 1936; to UP 3800-3814 in 1944 to clear the 3900 series for use by new 4664-5 class Challengers
c. Eight locomotives (UP 3801, 3802, 3804, 3807, 3809, 3810, 3811, 3814) were converted to coal burners in 1949 and renumbered to UP 3701-3714; all eight locomotives were converted back to oil burners in 1950 and renumbered back to their 3800 series numbers
d. (Read a brief narrative written by Allen Copeland in 1978)
   

UP 4-6-6-4 -- 25 locomotives "Light Challengers"

1944 UP
Number
First
Number
Date To
3800 Series
Builder Builder
Number
Date
Built
1949-1950
UP Number
Date
Vacated
UP 3815 UP 3915 Apr 1944 Schenectady 68924 Aug 1937   Dec 1958
UP 3816 UP 3916 Apr 1944 Schenectady 68925 Aug 1937   Apr 1957
UP 3817 UP 3917 Apr 1944 Schenectady 68926 Aug 1937 UP 3717 Jun 1957
UP 3818 UP 3918 Apr 1944 Schenectady 68927 Aug 1937 UP 3718 Mar 1961
UP 3819 UP 3919 Apr 1944 Schenectady 68928 Aug 1937   Jul 1957
UP 3820 UP 3920 Apr 1944 Schenectady 68929 Aug 1937   Aug 1957
UP 3821 UP 3921 Apr 1944 Schenectady 68930 Aug 1937   Apr 1957
UP 3822 UP 3922 Apr 1944 Schenectady 68931 Aug 1937   Sep 1957
UP 3823 UP 3923 Apr 1944 Schenectady 68932 Aug 1937   Jul 1959
UP 3824 UP 3924 Apr 1944 Schenectady 68933 Aug 1937   Jul 1957
UP 3825 UP 3925 Apr 1944 Schenectady 68934 Aug 1937   Apr 1957
UP 3826 UP 3926 Apr 1944 Schenectady 68935 Aug 1937   Nov 1956
UP 3827 UP 3927 Apr 1944 Schenectady 68936 Aug 1937   Dec 1958
UP 3828 UP 3928 Apr 1944 Schenectady 68937 Aug 1937   Jul 1959
UP 3829 UP 3929 Apr 1944 Schenectady 68938 Aug 1937   Jul 1957
UP 3830 UP 3930 (1st) Apr 1944 Schenectady 68939 Aug 1937   May 1959
UP 3831 UP 3931 (1st) Apr 1944 Schenectady 68940 Aug 1937   Jun 1957
UP 3832 UP 3932 (1st) Apr 1944 Schenectady 68941 Aug 1937   May 1959
UP 3833 UP 3933 (1st) Apr 1944 Schenectady 68942 Aug 1937   Nov 1956
UP 3834 UP 3934 (1st) Apr 1944 Schenectady 68943 Aug 1937   Nov 1954
UP 3835 UP 3935 (1st) Apr 1944 Schenectady 68944 Aug 1937   Nov 1956
UP 3836 UP 3936 (1st) Apr 1944 Schenectady 68945 Aug 1937   Nov 1956
UP 3837 UP 3937 (1st) Apr 1944 Schenectady 68946 Aug 1937   Jul 1957
UP 3838 UP 3938 (1st) Apr 1944 Schenectady 68947 Aug 1937   May 1959
UP 3839 UP 3939 (1st) Apr 1944 Schenectady 68948 Aug 1937   Aug 1957

Description:

CS Class: CSA-2
Cabside Class: CSA-69
Drive Wheel Diameter: 69 inches
Cylinders: 22&22x32 inches
Maximum Tractive Effort: 97,400 pounds
Weight on Drivers: 403,000 pounds (as built) (in later years their weight-on-drivers varied between 399,660 pounds and 407,610 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine Only, UP 3915-3933): 582,000 pounds (as built) (in later years their weight varied between 569,820 pounds and 590,550 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine Only, UP 3934-3939): 584,100 pounds (as built) (in later years their weight varied between 569,820 pounds and 590,550 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine and Tender, UP 3815-3833): 894,000 pounds (as built) (varied between 892,420 pounds and 915,000 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine and Tender, UP 3834-3839): 896,100 pounds (as built) (varied between 892,420 pounds and 915,000 pounds depending on type of feedwater heater and weight of front engine)
Fuel: Oil (two locomotives converted to coal then back to oil)

General Notes:

a. Challenger Simple Articulated (CSA)
b. UP 3815-3839 were built as UP 3915-3939 in 1937; to UP 3815-3839 in 1944 to clear the 3900 series for use by new 4664-5 class Challengers
c. UP 3817 and 3818 were built as oil burners; converted to coal-burners in 1949 and renumbered to UP 3717 and 3718; converted back to oil burners in 1950 and renumbered back to UP 3817 and 3818.
d. UP 3834-3839 (six locomotives) were built as coal burners; converted to oil burners upon delivery and assigned to passenger service on the LA&SL.
e. (Read a brief narrative written by Allen Copeland in 1978)
   

UP 4-6-6-4 -- 15 locomotives "Light Challengers"

Road
Number
Builder Builder
Number
Date
Built
Date
Renumbered
1944 UP
Number
UP 3900 Schenectady 68745 Sep 1936 Apr 1944 UP 3800
UP 3901 Schenectady 68746 Sep 1936 Apr 1944 UP 3801
UP 3902 Schenectady 68747 Sep 1936 Apr 1944 UP 3802
UP 3903 Schenectady 68748 Sep 1936 Apr 1944 UP 3803
UP 3904 Schenectady 68749 Sep 1936 Apr 1944 UP 3804
UP 3905 Schenectady 68750 Sep 1936 Apr 1944 UP 3805
UP 3906 Schenectady 68751 Sep 1936 Apr 1944 UP 3806
UP 3907 Schenectady 68752 Sep 1936 Apr 1944 UP 3807
UP 3908 Schenectady 68753 Sep 1936 Apr 1944 UP 3808
UP 3909 Schenectady 68754 Sep 1936 Apr 1944 UP 3809
UP 3910 Schenectady 68755 Sep 1936 Apr 1944 UP 3810
UP 3911 Schenectady 68756 Sep 1936 Apr 1944 UP 3811
UP 3912 Schenectady 68757 Sep 1936 Apr 1944 UP 3812
UP 3913 Schenectady 68758 Sep 1936 Apr 1944 UP 3813
UP 3914 Schenectady 68759 Sep 1936 Apr 1944 UP 3814

Description:

CS Class: CSA-1
Cabside Class: CSA-69
Drive Wheel Diameter: 69 inches
Cylinders: 22&22x32 inches
Maximum Tractive Effort: 97,400 pounds
Weight on Drivers: 386,000 pounds (as built) (in later years their weight-on-drivers varied between 399,660 pounds and 407,610 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine Only): 566,000 pounds (as built) (in later years their weight varied between 569,820 pounds and 590,550 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine and Tender): 876,000 pounds (as built) (varied between 892,420 pounds and 915,000 pounds depending on type of feedwater heater and weight of front engine))
Fuel: Coal (converted to oil in 1941-1943)

General Notes:

a. Challenger Simple Articulated (CSA)
b. UP 3900-3914 were built in 1936 was coal burners; converted to oil burners starting in September 1941; completed in March 1943
c. Built as UP 3900-3914 in 1936; to UP 3800-3814 in 1944 to clear the 3900 series for use by new 4664-5 class Challengers
d. (Read a brief narrative written by Allen Copeland in 1978)
   

UP 4-6-6-4 -- 25 locomotives "Light Challengers"

Road
Number
Builder Builder
Number
Date
Built
Date
Renumbered
1944 UP
Number
UP 3915 Schenectady 68924 Aug 1937 Apr 1944 UP 3815
UP 3916 Schenectady 68925 Aug 1937 Apr 1944 UP 3816
UP 3917 Schenectady 68926 Aug 1937 Apr 1944 UP 3817
UP 3918 Schenectady 68927 Aug 1937 Apr 1944 UP 3818
UP 3919 Schenectady 68928 Aug 1937 Apr 1944 UP 3819
UP 3920 Schenectady 68929 Aug 1937 Apr 1944 UP 3820
UP 3921 Schenectady 68930 Aug 1937 Apr 1944 UP 3821
UP 3922 Schenectady 68931 Aug 1937 Apr 1944 UP 3822
UP 3923 Schenectady 68932 Aug 1937 Apr 1944 UP 3823
UP 3924 Schenectady 68933 Aug 1937 Apr 1944 UP 3824
UP 3925 Schenectady 68934 Aug 1937 Apr 1944 UP 3825
UP 3926 Schenectady 68935 Aug 1937 Apr 1944 UP 3826
UP 3927 Schenectady 68936 Aug 1937 Apr 1944 UP 3827
UP 3928 Schenectady 68937 Aug 1937 Apr 1944 UP 3828
UP 3929 Schenectady 68938 Aug 1937 Apr 1944 UP 3839
UP 3930 (1st) Schenectady 68939 Aug 1937 Apr 1944 UP 3830
UP 3931 (1st) Schenectady 68940 Aug 1937 Apr 1944 UP 3831
UP 3932 (1st) Schenectady 68941 Aug 1937 Apr 1944 UP 3832
UP 3933 (1st) Schenectady 68942 Aug 1937 Apr 1944 UP 3833
UP 3934 (1st) Schenectady 68943 Aug 1937 Apr 1944 UP 3834
UP 3935 (1st) Schenectady 68944 Aug 1937 Apr 1944 UP 3835
UP 3936 (1st) Schenectady 68945 Aug 1937 Apr 1944 UP 3836
UP 3937 (1st) Schenectady 68946 Aug 1937 Apr 1944 UP 3837
UP 3938 (1st) Schenectady 68947 Aug 1937 Apr 1944 UP 3838
UP 3939 (1st) Schenectady 68948 Aug 1937 Apr 1944 UP 3839

Description:

CS Class: CSA-2
Cabside Class: CSA-69
Drive Wheel Diameter: 69 inches
Cylinders: 22&22x32 inches
Maximum Tractive Effort: 97,400 pounds
Weight on Drivers: 403,000 pounds (as built) (in later years their weight-on-drivers varied between 399,660 pounds and 407,610 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine Only, UP 3915-3933): 582,000 pounds (as built) (in later years their weight varied between 569,820 pounds and 590,550 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine Only, UP 3934-3939): 584,100 pounds (as built) (in later years their weight varied between 569,820 pounds and 590,550 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine and Tender, UP 3815-3833): 894,000 pounds (as built) (varied between 892,420 pounds and 915,000 pounds depending on type of feedwater heater and weight of front engine)
Weight in Working Order (Engine and Tender, UP 3834-3839): 896,100 pounds (as built) (varied between 892,420 pounds and 915,000 pounds depending on type of feedwater heater and weight of front engine)
Fuel: Coal (converted to oil)

General Notes:

a. Challenger Simple Articulated (CSA)
b. UP 3915-3933 were built in 1937 as coal burners; converted to oil burners starting in 1941-1943
c. UP 3834-3839 (six locomotives) were built as coal burners; converted to oil burners upon delivery and assigned to passenger service on the LA&SL.
d. Built as UP 3915-3939 in 1937; renumbered to UP 3815-3839 in 1944 to clear the 3900 series for use by new 4664-5 class Challengers
e. (Read a brief narrative written by Allen Copeland in 1978)
   

UP 4-6-6-4 -- 20 locomotives

Road
Number
Builder Builder
Number
Date
Built
Date
Vacated
1952 UP
Number
UP 3930 (2nd) Schenectady 72792 Aug 1944 1952 UP 3700 (2nd)
UP 3931 (2nd) Schenectady 72793 Aug 1944 1952 UP 3701 (3rd)
UP 3932 (2nd) Schenectady 72794 Aug 1944 1952 UP 3702 (3rd)
UP 3933 (2nd) Schenectady 72795 Aug 1944 Jun 1959  
UP 3934 (2nd) Schenectady 72796 Aug 1944 1952 UP 3703 (2nd)
UP 3935 (2nd) Schenectady 72797 Aug 1944 Jun 1959  
UP 3936 (2nd) Schenectady 72798 Aug 1944 Jun 1959  
UP 3937 (2nd) Schenectady 72799 Aug 1944 1952 UP 3704 (3rd)
UP 3938 (2nd) Schenectady 72800 Aug 1944 1952 UP 3705 (2nd)
UP 3939 (2nd) Schenectady 72801 Aug 1944 Jun 1959  
UP 3940 Schenectady 72802 Aug 1944 Jul 1959  
UP 3941 Schenectady 72803 Aug 1944 Sep 1959  
UP 3942 Schenectady 72804 Aug 1944 Dec 1959  
UP 3943 Schenectady 72805 Aug 1944 1952 UP 3706
UP 3944 Schenectady 72806 Aug 1944 1952 UP 3707 (2nd)
UP 3945 Schenectady 72807 Aug 1944 Oct 1959  
UP 3946 Schenectady 72808 Aug 1944 Jul 1960  
UP 3947 Schenectady 72809 Aug 1944 Dec 1959  
UP 3948 Schenectady 72810 Aug 1944 Dec 1959  
UP 3949 Schenectady 72811 Aug 1944 Oct 1959  

Description:

Cabside Class: 4664-5
Drive Wheel Diameter: 69 inches
Cylinders: 21&21x32 inches
Maximum Tractive Effort: 97,350 pounds
Weight on Drivers: 406,200 pounds
Weight in Working Order (Engine Only): 634,500 pounds
Weight in Working Order (Engine and Tender): 1,071,000 pounds
Fuel: Coal

General Notes:

a. Eight UP 3900 series locomotives were converted from coal to oil in 1952 and renumbered to UP 3700-3707
   

UP 4-6-6-4 -- 20 locomotives

Road
Number
Builder Builder
Number
Date
Built
Date
Vacated
UP 3950 Schenectady 69760 May 1942 Mar 1961
UP 3951 Schenectady 69761 May 1942 Dec 1959
UP 3952 Schenectady 69762 May 1942 Jul 1960
UP 3953 Schenectady 69763 May 1942 Feb 1960
UP 3954 Schenectady 69764 May 1942 Feb 1960
UP 3955 Schenectady 69765 May 1942 Dec 1958
UP 3956 Schenectady 69766 May 1942 Feb 1960
UP 3957 Schenectady 69767 May 1942 Feb 1960
UP 3958 Schenectady 69768 May 1942 Mar 1960
UP 3959 Schenectady 69769 May 1942 Jul 1960
UP 3960 Schenectady 69770 May 1942 Dec 1958
UP 3961 Schenectady 69771 May 1942 Dec 1958
UP 3962 Schenectady 69772 May 1942 Mar 1960
UP 3963 Schenectady 69773 May 1942 Oct 1959
UP 3964 Schenectady 69774 May 1942 Oct 1959
UP 3965 Schenectady 69775 May 1942 Jul 1960
UP 3966 Schenectady 69776 May 1942 Mar 1960
UP 3967 Schenectady 69777 May 1942 Mar 1960
UP 3968 Schenectady 69778 May 1942 Apr 1960
UP 3969 Schenectady 69779 May 1942 Apr 1960

Description:

Cabside Class: 4664-3
Drive Wheel Diameter: 69 inches
Cylinders: 21721x32 inches
Maximum Tractive Effort: 97,350 pounds
Weight on Drivers: 403,700 pounds
Weight in Working Order (Engine Only): 627,000 pounds
Weight in Working Order (Engine and Tender): 1,063,500 pounds
Fuel: Coal
 

UP 4-6-6-4 -- 25 locomotives

Road
Number
Builder Builder
Number
Date
Built
Date
Vacated
1952 UP
Number
Notes
UP 3975 Schenectady 70158 Jun 1943 1952 UP 3708  
UP 3976 Schenectady 70159 Jun 1943 1952 UP 3709 (2nd)  
UP 3977 Schenectady 70160 Jun 1943 1952 UP 3710 (2nd) 1
UP 3978 Schenectady 70161 Jun 1943 1952 UP 3711 (2nd)  
UP 3979 Schenectady 70162 Jun 1943 1952 UP 3712  
UP 3980 Schenectady 70169 Jun 1943 1952 UP 3713  
UP 3981 Schenectady 70170 Jun 1943 1952 UP 3714 (2nd)  
UP 3982 Schenectady 70171 Jun 1943 1952 UP 3715  
UP 3983 Schenectady 70172 Jun 1943 1952 UP 3716  
UP 3984 Schenectady 70173 Jun 1943 1952 UP 3717 (2nd)  
UP 3985 Schenectady 70174 Jun 1943     2
UP 3986 Schenectady 70175 Jun 1943 Apr 1960    
UP 3987 Schenectady 70176 Jun 1943 Apr 1960    
UP 3988 Schenectady 70177 Jun 1943 Oct 1960    
UP 3989 Schenectady 70178 Jun 1943 Aug 1960    
UP 3990 Schenectady 70179 Jun 1943 Aug 1960    
UP 3991 Schenectady 70180 Jun 1943 Mar 1961    
UP 3992 Schenectady 70181 Jun 1943 Aug 1960    
UP 3993 Schenectady 70182 Jun 1943 Aug 1960    
UP 3994 Schenectady 70678 Jul 1943 Jul 1959    
UP 3995 Schenectady 70679 Jul 1943 Oct 1960    
UP 3996 Schenectady 70680 Jul 1943 Oct 1960    
UP 3997 Schenectady 70681 Jul 1943 Oct 1960    
UP 3998 Schenectady 70682 Jul 1943 Dec 1960    
UP 3999 Schenectady 70683 Jul 1943 Dec 1960    

Description:

Cabside Class: 4664-4
Drive Wheel Diameter: 69 inches
Cylinders: 21&21x32 inches
Maximum Tractive Effort: 97,350 pounds
Weight on Drivers: 407,500 pounds
Weight in Working Order (Engine Only): 633,500 pounds
Weight in Working Order (Engine and Tender): 1,070,000 pounds
Fuel: Coal (UP 3975-3984 converted to oil)

General Notes:

a. UP 3975-3984 (10 locomotives) were painted two-tone gray beginning in December 1946, while assigned to passenger service on the Northwestern District (OWRR&N); repainted back to standard black after being shopped and assigned to helper service east of Ogden, Utah.
b. UP 3975-3980 (5 locomotives) were converted to oil in November 1944 and assigned to the Los Angeles passenger pool, generally operating between Caliente and Los Angeles. Records indicate UP 3975-3980 joined the Huntington-Portland-Seattle pool in August 1946. (Gordon McCulloh, email dated March 9, 2014)
c. UP 3981-3984 (5 locomotives) were converted to oil in November 1946 and were sent to the Northwest Division.  Smoke lifting Wind Wings were being added beginning late in 1945. UP 3977 was photographed with them on January 6, 1946. (Gordon McCulloh, email dated March 9, 2014)
d. UP 3975-3984 (10 locomotives) were re-assigned to helper service on UP's wasatch grade east of Ogden, Utah in 1950, and were renumbered to the UP-3700 series in 1952. (Read more about UP 3975-3984)

Notes:

1. UP 3977 was renumbered to UP 3710 (2nd) in 1952; used in snow melting service in North Platte yard after October 1959, renumbered to UP 900079, "Roadway Locomotive" in November 1961; stored in the roundhouse at North Platte, Nebraska, and reported to have been fired up and prepared each December for snow melting service (photo in Trains magazine, May 1967, on December 6, 1966); donated to City of North Platte in June 1968; renumbered back to UP 3977; displayed at Cody Park, North Platte, Nebraska.
2. UP 3985 was first retired in July 1962; stored at Cheyenne, Wyoming, until placed on display at the Cheyenne depot in October 1974; removed from display in September 1979 and returned to service April 1981 (reinstated to roster in March 1981). (Read more about UP 3985 in service after 1981 as part of UP's Heritage Fleet)

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