Last revised: August 27, 2024
By: Adam Burns
The oddly named cow-calf design was released only by Electro-Motive, first built as an experimental prior to World War II. It was essentially a different name for "A" and "B" (cabless) locomotives, commonly found in the F and E series cab models.
EMD took the same concept and applied it to its switcher line for use in transfer and yard work by providing a cabless "B" unit mated to an "A." Doing so offered more horsepower and tractive effort without the need of supplying an additional crew.
As with transfer models offered by other builders, railroads remained largely disinterested in such a specialized locomotive, even for EMD's highly respectable designs rolling out of La Grange at the time.
Overall, few cow-calves were sold among the seven different types offered although they did prove more successful than similar examples cataloged by other manufacturers. As the years passed railroads tended to lashup "A's" and "B's" of different models together.
The cow-calf term is unique into itself; technically it is neither a mother-slug (a fully operational locomotive coupled to a unit with no prime mover, only traction motors and/or ballasting for increased tractive effort) nor an actual "B" unit.
Instead the design refers solely to switchers built by Electro-Motive. The "cow-calf" designation was not the product of EMD, merely a nickname adopted by train enthusiasts.
EMD referred to these designs as transfer switchers, the first of which was an experimental. This unit, numbered 9201 (later changed to #9202) and listed as the T-Model (for Transfer) was a single, center-cab locomotive built in 1936 for Illinois Central, which intended to use it in yard service between Chicago and Markham Yard.
It was constructed by what was then the Electro-Motive Corporation featuring a pair of 900 horsepower, Winton V-12 201-A prime movers with the carbody supplied by the St. Louis Car Company.
Railroad officials were pleased with the model although its unique B-B+B-B wheel arrangement and longer frame caused the unit to develop a sag beneath the cab. The issue was later resolved by EMD.
In 1940 the first, true cow-calf model was outshopped by EMD; designated class TR (TRansfer), it was based on the popular 1,000 horsepower NW2.
However, instead of Winton prime movers the locomotive featured EMD's highly reliable 12-cylinder, model 567 power plant.
The IC was so pleased with this latest design it ultimately purchased three sets, numbered 9203A–9205A/9203B-9205B.
During their long career these cow-calves spent most of their time in yard service pushing long cuts of freight cars over the hump at Markham.
It was the only system to purchase the TR, as well as the following TR1 of 1941. This particular variant featured a very interesting extended carbody based on the NW3.
It was capable of producing a combined 2,700 horsepower and was essentially an FT in a switcher carbody, even sporting Blomberg trucks; only two sets were built.
In 1945 EMD began production on the 2,000-horsepower TR2, also based from the NW2 but sporting the updated 567A power plant.
The most successful of the series, 36 sets were built for seven different lines by 1949. In a bit of comedy, names for future cow-calf combinations became even more interesting.
During the summer of that same year (1949) the Chesapeake & Ohio took delivery of the TR3; a three-unit, cow-calf-calf combination, or "herd," which could produce 3,000 horsepower.
TR (NW2)
Entered Production | 2/1940 (Illinois Central #9203) |
Years Produced | 2/1940 - 11/1940 |
EMD Class | TR |
Engines (2) | 567 (6 Cylinder) |
Engine Builder | GM/EMD |
Horsepower | 2000 |
RPM | 800 |
Length (End of Couplers) | 44' 5" (Per Locomotive) |
Total Length (End of Couplers) | 86' 5" |
Height (Top Of Rail To Top Of Cab) | 14' 6 ¼" |
Width | 10' 0" |
Weight | 250,000 Lbs (Per Locomotive) |
Fuel Capacity | 600 Gallons |
Air Compressor | 3C2C (Westinghouse) |
Air Brake Schedule | 24EL (Westinghouse) |
Trucks | B-B |
Truck Type | GRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A) |
Truck Wheelbase | 8' 0" |
Wheel Size | 40" |
Traction Motors (Per Locomotive) | D7 (4), GM/EMD |
Traction Generator | D4/D4D, GM/EMD |
MU (Multiple-Unit) | Yes |
Dynamic Brakes | No |
Gear Ratio | 62:15 |
Tractive Effort/Starting | 62,500 Lbs |
Top Speed | 65 mph |
TR1 (FT)
Entered Production | 4/1941 (Illinois Central #9250-9251) |
Years Produced | 4/1941 - 5/1941 |
EMD Class | TR |
Engines (2) | 567 (8 Cylinder) |
Engine Builder | GM/EMD |
Horsepower | 2700 |
RPM | 800 |
Length | 52' 1 1/2" (Per Locomotive) |
Height (Top Of Rail To Top Of Cab) | 14' 6 ¼" |
Width | 9' 11 ½" |
Weight | 230,000 Lbs |
Fuel Capacity | 600 Gallons |
Air Compressor | 3C2C (Westinghouse) |
Air Brake Schedule | 24EL (Westinghouse) |
Trucks | B-B |
Truck Type | Blomberg |
Truck Wheelbase | 9' 0" |
Wheel Size | 40" |
Traction Motors (Per Locomotive) | D7 (4), GM/EMD |
Traction Generator | D12, GM/EMD |
MU (Multiple-Unit) | Yes |
Dynamic Brakes | No |
Gear Ratio | 62:15 |
Tractive Effort/Starting | 55,000 Lbs |
Top Speed | 65 mph |
This variant was a stretched version of an NW, essentially an NW3 which Electro-Motive briefly marketed.
Internally, it was nearly identical to an FT sporting a 567A prime mover capable of producing 1,350 horsepower each. In addition, it rode on Blomberg trucks.
TR2 (NW2)
Entered Production | 11/1945 (Illinois Central #9206A-9206B) |
Years Produced | 11/1945 - 12/1949 |
EMD Class | TR2 |
Engines (2) | 567A (6 Cylinder) |
Engine Builder | GM/EMD |
Horsepower | 2000 |
RPM | 800 |
Length | 44' 5" (Per Locomotive) |
Height (Top Of Rail To Top Of Cab) | 14' 6 ¼" |
Width | 10' 0" |
Weight | 250,000 Lbs (Per Locomotive) |
Fuel Capacity | 600 Gallons |
Air Compressor | 3C2C (Westinghouse) |
Air Brake Schedule | 24EL (Westinghouse) |
Trucks | B-B |
Truck Type | GRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A) |
Truck Wheelbase | 8' 0" |
Wheel Size | 40" |
Traction Motors (Per Locomotive) | D7 (4), GM/EMD |
Traction Generator | D4/D4D, GM/EMD |
Auxiliary Generator | General Motors/EMD |
MU (Multiple-Unit) | Yes |
Dynamic Brakes | No |
Gear Ratio | 62:15 |
Tractive Effort/Starting | 62,500 Lbs |
Top Speed | 65 mph |
TR3 (NW2)
Entered Production | 7/1949 (Chesapeake & Ohio #6500) |
Years Produced | 7/1949 - 10/1949 |
EMD Class | TR3 |
Engines (3) | 567A (6 Cylinder) |
Engine Builder | GM/EMD |
Horsepower | 3000 |
RPM | 800 |
Length | 44' 5" (Per Locomotive) |
Height (Top Of Rail To Top Of Cab) | 14' 6 ¼" |
Width | 10' 0" |
Weight | 250,000 Lbs (Per Locomotive) |
Fuel Capacity | 600 Gallons |
Air Compressor | 3C2C (Westinghouse) |
Air Brake Schedule | 24EL (Westinghouse) |
Trucks | B-B |
Truck Type | GRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A) |
Truck Wheelbase | 8' 0" |
Wheel Size | 40" |
Traction Motors (Per Locomotive) | D7 (4), GM/EMD |
Traction Generator | D4/D4D, GM/EMD |
Auxiliary Generator | General Motors/EMD |
MU (Multiple-Unit) | Yes |
Dynamic Brakes | No |
Gear Ratio | 62:15 |
Tractive Effort/Starting | 62,500 Lbs |
Top Speed | 65 mph |
TR4 (SW7)
Entered Production | 6/1950 (Chesapeake & Ohio #6000A) |
Years Produced | 6/1950 - 1/1951 |
EMD Class | TR4 |
Engines (2) | 567A (6 Cylinder) |
Engine Builder | GM/EMD |
Horsepower | 2400 |
RPM | 800 |
Length | 44' 5" (Per Locomotive) |
Height (Top Of Rail To Top Of Cab) | 14' 6 ½" |
Width | 9' 11 ½" |
Weight | 250,000 Lbs (Per Locomotive) |
Fuel Capacity | 600 Gallons |
Air Compressor | WXO (GM/EMD) |
Air Brake Schedule | 24EL (Westinghouse) |
Trucks | B-B |
Truck Type | GRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A) |
Truck Wheelbase | 8' 0" |
Wheel Size | 40" |
Traction Motors (Per Locomotive) | D7 (4), GM/EMD |
Traction Generator | D4/D4D, GM/EMD |
Auxiliary Generator | General Motors/EMD |
MU (Multiple-Unit) | Yes |
Dynamic Brakes | No |
Gear Ratio | 62:15 |
Tractive Effort/Starting | 62,500 Lbs |
Top Speed | 65 mph |
TR5 (SW9)
Entered Production | 3/1951 (Union Railroad #701-702) |
Years Produced | 3/1951 - 10/1951 |
EMD Class | TR5 |
Engines (2) | 567B (6 Cylinder) |
Engine Builder | GM/EMD |
Horsepower | 2400 |
RPM | 800 |
Length | 44' 5" (Per Locomotive) |
Height (Top Of Rail To Top Of Cab) | 14' 6 ½" |
Width | 9' 11 1/2" |
Weight | 250,000 Lbs (Per Locomotive) |
Fuel Capacity | 600 Gallons |
Air Compressor | WXO (GM/EMD) |
Air Brake Schedule | 6BL (Westinghouse) |
Trucks | B-B |
Truck Type | GRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A) |
Truck Wheelbase | 8' 0" |
Wheel Size | 40" |
Traction Motors (Per Locomotive) | D37 (4), GM/EMD |
Traction Generator | D15C, GM/EMD |
Auxiliary Generator | General Motors/EMD |
MU (Multiple-Unit) | Yes |
Dynamic Brakes | No |
Gear Ratio | 62:15 |
Tractive Effort/Starting | 62,500 Lbs |
Top Speed | 65 mph |
TR6 (SW8)
Entered Production | 11/1950 (Electro-Motive #1600-1600B) |
Years Produced | 11/1950 - 8/1953 |
EMD Class | TR6 |
Engines (2) | 567B (4 Cylinder) |
Engine Builder | GM/EMD |
Horsepower | 1600 |
RPM | 800 |
Length | 44' 5" (Per Locomotive) |
Height (Top Of Rail To Top Of Cab) | 14' 6 ½" |
Width | 10' |
Weight | 230,000 Lbs (Per Locomotive) |
Fuel Capacity | 600 Gallons |
Air Compressor | WXO (Gardner-Denver) |
Air Brake Schedule | 6BL (Westinghouse) |
Trucks | B-B |
Truck Type | GRS Rigid Bolster, Drop-Side Equalizer (AAR Type-A) |
Truck Wheelbase | 8' 0" |
Wheel Size | 40" |
Traction Motors (Per Locomotive) | D37 (4), GM/EMD |
Traction Generator | D15C, GM/EMD |
Auxiliary Generator | General Motors/EMD |
MU (Multiple-Unit) | Yes |
Dynamic Brakes | No |
Gear Ratio | 62:15 |
Tractive Effort/Starting | 69,000 Lbs (at 30% adhesion) |
Top Speed | 65 mph |
According to Electro-Motive's Operating Manual #2303, the D15A main generator and D27 traction motors were used in NW2's after August, 1949 and in SW7's after October, 1949.
(Total Built = 3 Sets)
Owner | Road Number | Serial Number | Order Number | Completion Date | Quantity |
---|---|---|---|---|---|
Illinois Central | 9203-9204 (A-B) | 1032-1033 | E286 | 2/1940 | 2 |
Illinois Central | 9205 (A-B) | 1190 | E345 | 11/1940 | 1 |
(Total Built = 2 Sets)
Owner | Road Number | Serial Number | Order Number | Completion Date | Quantity |
---|---|---|---|---|---|
Illinois Central | 9250-9251 (A-B) | 1191 | E358 | 4/1941-5/1941 | 2 |
(Total Built = 36 Sets)
Owner | Road Number | Serial Number | Order Number | Completion Date | Quantity |
---|---|---|---|---|---|
Illinois Central | 9206A (A), 9206B (B) | 2067-2068 | E552 | 11/1945 | 2 |
Southern Railway | 2400A-2403A (A) | 4764-4767 | E829 | 8/1947 | 4 |
Southern Railway | 2400B-2403B (B) | 4768-4771 | E829 | 8/1947 | 4 |
Southern Railway | 2404A (A), 2404B (B) | 5002-5003 | E829 | 8/1947 | 2 |
Electro-Motive (Demonstrator) | 912A (A), 912B (B)* | 5514-5515 | E912 | 10/1947 | 2 |
Chicago, Burlington & Quincy | 9401A-9405A (A) | 6563-6567 | E1009 | 2/1949 | 5 |
Chicago, Burlington & Quincy | 9401B-9405B (B) | 6568-6572 | E1009 | 2/1949 | 5 |
Chicago, Burlington & Quincy | 9406A-9408A (A) | 6573-6575 | E1009 | 2/1949-3/1949 | 3 |
Chicago, Burlington & Quincy | 9406B-9408B (B) | 6576-6578 | E1009 | 2/1949-3/1949 | 3 |
Chicago, Burlington & Quincy | 9409A (A), 9409B (B) | 6579-6580 | E1009 | 3/1949 | 2 |
Chicago Great Western | 58A (A), 58B (B) | 6877-6878 | E1097 | 8/1948 | 2 |
Chicago Great Western | 59A-65A (A) | 6879-6885 | E1033 | 7/1949-8/1949 | 7 |
Chicago Great Western | 59B-65B (A) | 6886-6892 | E1033 | 7/1949-8/1949 | 7 |
Chicago Great Western | 66A (A), 66B (B) | 6893-6894 | E1033 | 7/1949 | 2 |
Milwaukee Road | 2000A (A), 2000B (B) | 7919-7920 | E1124 | 12/1949 | 2 |
Chicago, Burlington & Quincy | 9410A-9413A (A) | 8505-8508 | E1179 | 11/1949 | 4 |
Chicago, Burlington & Quincy | 9410B-9411B (B) | 8509-8510 | E1179 | 11/1949 | 2 |
Chicago, Burlington & Quincy | 9412B-9413B (B) | 8598-8599 | E1179 | 11/1949 | 2 |
Chicago & North Western | 2000A-2001A (A) | 10021-10022 | E1305 | 10/1949 | 2 |
Chicago & North Western | 2000B-2001B (B) | 10023-10024 | E1305 | 10/1949 | 2 |
Illinois Central | 9207A (A), 9207B (B) | 10056-10057 | 6007 | 12/1949 | 2 |
Illinois Central | 9208A (A), 9208B (B) | 10058-10059 | 6007 | 12/1949 | 2 |
Belt Railway Of Chicago | 500A-501A (A) | 10512-10513 | 6027 | 11/1949-12/1949 | 2 |
Belt Railway Of Chicago | 500B-501B (B) | 10514-10515 | 6027 | 11/1949-12/1949 | 2 |
* Sold to Chicago, Burlington & Quincy as #9400A-9400B.
(Total Built = 2 Sets)
Owner | Road Number | Serial Number | Order Number | Completion Date | Quantity |
---|---|---|---|---|---|
Chesapeake & Ohio | 6500A (A) | 10253 | 6018 | 7/1949 | 1 |
Chesapeake & Ohio | 6500C, 6500B (B) | 10254-10255 | 6018 | 7/1949 | 2 |
Chesapeake & Ohio | 6501A (A) | 10256 | 6018 | 10/1949 | 1 |
Chesapeake & Ohio | 6501C, 6501B (B) | 10257-10258 | 6018 | 10/1949 | 2 |
(Total Built = 15 Sets)
Owner | Road Number | Serial Number | Order Number | Completion Date | Quantity |
---|---|---|---|---|---|
Belt Railway of Chicago | 502A-506A (A) | 10516-10520 | 4032 | 9/1950 | 5 |
Belt Railway of Chicago | 502B-506B (B) | 10521-10525 | 4032 | 9/1950 | 5 |
Milwaukee Road | 2001A (A) | 11402 | 4051 | 9/1950 | 1 |
Milwaukee Road | 2001B (B) | 11403 | 4051 | 9/1950 | 1 |
Chesapeake & Ohio | 6000A (A) | 11945 | 6124 | 6/1950 | 1 |
Chesapeake & Ohio | 6000B (B) | 11946 | 6124 | 6/1950 | 1 |
Chesapeake & Ohio | 6001A (A) | 11947 | 6124 | 6/1950 | 1 |
Chesapeake & Ohio | 6001B (B) | 11948 | 6124 | 6/1950 | 1 |
Santa Fe | 2418 (A) | 12360 | 6146 | 6/1950 | 1 |
Santa Fe | 2418A (B) | 12361 | 6146 | 6/1950 | 1 |
Milwaukee Road | 2002A-2006A (A) | 12447-12451 | 4071 | 1/1951 | 5 |
Milwaukee Road | 2002B-2006B (B) | 12452-12456 | 4071 | 1/1951 | 5 |
Santa Fe | 2419 (A) | 13827 | 6214 | 1/1951 | 1 |
Santa Fe | 2419A (B) | 13828 | 6214 | 1/1951 | 1 |
(Total Built = 10 Sets And 2 Calves)
Owner | Road Number | Serial Number | Order Number | Completion Date | Quantity |
---|---|---|---|---|---|
Union Railroad | 701-702 (A) | 8544-8545 | E1187 | 3/1951 | 2 |
Union Railroad | 701C-702C (B) | 8546-8547 | E1187 | 3/1951 | 2 |
Union Railroad | 703C-704C (B) | 14786-14787 | 6253 | 10/1951 | 2 |
Union Pacific | 1870A-1877A (A) | 15068-15075 | 6284 | 9/1951-10/1951 | 8 |
Union Pacific | 1870B-1877B (B) | 15076-15083 | 6284 | 9/1951-10/1951 | 8 |
(Total Built = 12 Sets)
Owner | Road Number | Serial Number | Order Number | Completion Date | Quantity |
---|---|---|---|---|---|
Electro-Motive (Demonstrator) | 1600 (A)* | 13549 | 15051 | 11/1950 | 1 |
Electro-Motive (Demonstrator) | 1600B (B)** | 13550 | 15051 | 11/1950 | 1 |
Oliver Iron Mining Company | 1207A-1209A (A) | 14829-14831 | 6321 | 10/1951-12/1951 | 3 |
Oliver Iron Mining Company | 1207B-1209B (B) | 14832-14834 | 6321 | 10/1951-12/1951 | 3 |
Oliver Iron Mining Company | 1210A-1211A (A) | 14835-14836 | 6332 | 12/1951 | 2 |
Oliver Iron Mining Company | 1210B-1211B (B) | 14837-14838 | 6332 | 12/1951 | 2 |
Southern Pacific | 4601-4603 (A) | 15084-15086 | 4100 | 10/1951 | 3 |
Southern Pacific | 4701-4703 (B) | 15117-15119 | 4100 | 10/1951 | 3 |
Oliver Iron Mining Company | 1212A (A) | 17052 | 6382 | 5/1952 | 1 |
Oliver Iron Mining Company | 1212B (B) | 17053 | 6382 | 5/1952 | 1 |
Oliver Iron Mining Company | 1213A (A) | 17054 | 6382 | 5/1952 | 1 |
Oliver Iron Mining Company | 121BA (B) | 17055 | 6382 | 5/1952 | 1 |
Oliver Iron Mining Company | 1216A (A) | 18619 | 6502 | 8/1953 | 1 |
Oliver Iron Mining Company | 1216B (B) | 18620 | 6502 | 8/1953 | 1 |
* Became Southern Pacific #4600 (A). Order number 4147.
** Became Southern Pacific #4700 (B). Order number 4147.
The C&O went on to purchase two, three-unit sets; #6500ABC-6501ABC. EMD's last three cow-calf models saw only modest sales:
Once again there were few buyers as only the Southern Pacific, which acquired four sets (including EMD's demonstrator), and the Oliver Iron Mining Company took orders.
By the early 1950s no more TR examples were outshopped although those that were remained in use for several years, many of which were rebuilt with cabs like the CB&Q's.
Oct 09, 24 10:21 PM
Oct 09, 24 03:10 PM
Oct 09, 24 03:09 PM