EMD DD35

From Wikipedia, the free encyclopedia
Jump to: navigation, search
EMD DD35
UP SD45 and DD35.jpg
Two Union Pacific Railroad EMD DD35s between a lead SD45 (#3638) and an unidentified trailing unit.
Specifications
Power type Diesel-electric
Builder General Motors Electro-Motive Division (EMD)
Model DD35
Build date 1963–1964
Total produced 30
AAR wheel arr. D-D
Gauge 4 ft 8 12 in (1,435 mm)
Prime mover Dual EMD 16-567D3A
Engine type 2 stroke diesel
Aspiration Turbocharged
Generator DC generator
Cylinder size 8 12 in × 10 in (216 mm × 254 mm)
Transmission diesel electric
Power output 5,000 horsepower (3,730 kW)
Locomotive brake Straight air, Dynamic
Train brakes Air
Career
Locale North America
Retired 1981
Disposition No surviving units[1]

The EMD DD35 was a 5,000 horsepower (3,700 kW) diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division for the Union Pacific Railroad and Southern Pacific Railroad. In the early 1960s, Union Pacific started asking for a 15,000 hp (11,200 kW) 3-unit locomotive set to not only replace their turbine locomotives, but to bring new generation of diesel locomotives to the states, and then put them into use. The DD35 was a cabless booster (B unit) locomotive that consisted of two GP35 locomotives on a common frame, riding on a pair of 4-axle Flexicoil trucks. The 4-axle truck was considered too harsh on the trackwork to be in the lead, and thus EMD's response to UP's request was a 4-unit (instead of the requested 3-unit set) locomotive set, consisting of a pair of 2,500 hp GP35s sandwiching a pair of DD35s, to make one 15,000 hp locomotive set.

EMD produced a demonstrator set like this in September 1963, painted in striking red and white (similar to the Frisco's livery). It was demonstrated on a number of railroads, but the only interest came from Union Pacific and Southern Pacific. UP bought the entire 4-unit demonstrator set, and followed up with an order for 25 more, which were delivered from May through September 1964. The two demonstrator locomotives were numbered 72B and 73B; the 25 production locomotives were assigned 74B through 98B.

Southern Pacific ordered a small, three-unit sample, which were shipped with older bearings from six F3B trade-in units, but ordered no more. They were numbered 8400-8402, later 9500-9502, and still later 9900-9902. They were used on SP's mainline between Los Angeles and New Orleans early in their lives, but were among the first locomotives stored whenever there was a downturn in traffic. Later, they were relegated to transfer service between West Colton and yards closer to Los Angeles, mainly Taylor Yard north of downtown. SP scrapped all three units in 1978 after their leases ran out.

The DD35s were initially quite unreliable; some of this was blamed on sand from the internal sandboxes getting in electrical gear, so new sandboxes were fitted on the walkways in 1969. The locomotives were among the last EMD road units to be built with DC generators and old-fashioned switchgear, which were more maintenance-intensive than later AC/DC equipment.

Once teething troubles had been surmounted, the DD35s were reasonably successful, but they were less flexible than smaller units and thus all of the original B units were withdrawn by 1977 as the railroads faced competition with automobile transportation. The DD35As survived a little longer, until 1981.

Original Buyers[edit]


Owner Quantity Numbers Notes
Southern Pacific Railroad 3 8400-8402
Union Pacific Railroad 27 72B-98B 72B and 73B ex EMD (demonstrators) 5653 and 5655

References[edit]