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The EMD DD35 was a
diesel-electric locomotive A diesel locomotive is a type of railway locomotive in which the power source is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving whee ...
of D-D
wheel arrangement In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...
built by
General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...
Electro-Motive Division Electro-Motive Diesel (abbreviated EMD) is a brand of diesel-electric locomotives, locomotive products and diesel engines for the rail industry. Formerly a division of General Motors, EMD has been owned by Progress Rail since 2010. Electro-Motiv ...
for the
Union Pacific Railroad The Union Pacific Railroad is a Railroad classes, Class I freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United Stat ...
and
Southern Pacific Railroad The Southern Pacific (or Espee from the railroad initials) was an American Railroad classes#Class I, Class I Rail transport, railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was oper ...
.


History

In the early 1960s, Union Pacific started asking for a 3-unit ''locomotive set'' to not only replace their turbine locomotives, but to bring a new generation of diesel locomotives to their rails, and then put them into use. The EMD (Electro Motive Division of General Motors) DD35 was a cabless booster (
B unit A B-unit, in railroad terminology, is a locomotive unit (generally a diesel locomotive) which does not have a control cab or crew compartment, and must therefore be operated in tandem with another coupled locomotive with a cab (an A-unit) ...
) locomotive that consisted of two GP35 locomotives prime movers (engines) and electrical systems, mounted on a common frame back-to-back, riding on a pair of 4-axle Flexicoil trucks, so each prime mover was powering a single set of 4 axles instead of two sets of 2 axles, as in the GP35. Being a "B-unit", the DD35 lacked any sort of cab, and could only be run on the main line when connected with another "A-unit" to control it; the DD35A is an "A-unit" version of this locomotive subsequently built in 1965. 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 (basically six GP35s in four units). EMD produced a demonstrator set like this in September 1963, painted in red and white (similar to the Frisco's livery). It was demonstrated on several railroads, but the only interest came from Union Pacific and Southern Pacific. UP bought the entire 4-unit demonstrator set, and followed 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 old-style 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 the SP's Sunset Route early in their lives, but were among the first locomotives sidelined 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
sandbox A sandbox is a sandpit, a wide, shallow playground construction to hold sand, often made of wood or plastic. Sandbox or sand box may also refer to: Arts, entertainment, and media * Sandbox (band), a Canadian rock music group * Sandbox (Gu ...
es getting in electrical gear, so new sandboxes were fitted on the walkways in 1969. They were among the last EMD road units to be built with DC generators and old-fashioned switchgear, which were more maintenance-intensive than the 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 fell on harder times. The DD35As survived until 1981. All were eventually scrapped.


Original Buyers



See also

*
EMD DD35A The EMD DD35A, also known as the EMD DDA35, was a diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division exclusively for the Union Pacific Railroad. They were a cab-equipped variant of the previous, ...
*
EMD DDA40X The EMD DDA40X is a 6,600 hp (4,943 kW) D-D locomotive, built by EMD from 1969 to 1971 exclusively for the Union Pacific Railroad. It is the most powerful diesel–electric locomotive model ever built on a single frame, having two 1 ...
*
EMD DDM45 The EMD DDM45 is a meter-gauge diesel-electric locomotive built by EMD. The DD in the name means that it has eight axles in two trucks, giving it a D-D wheel arrangement, while the M stands for the meter-gauge track it was to operate on, and ...
*
ALCO Century 855 The ALCO Century 855 was a model of diesel-electric locomotive built in 1964 by the American Locomotive Company for the Union Pacific. The locomotive was notable for being ALCO's most powerful diesel-electric locomotive and, at the time, the mos ...
* GE U50C


References

* * * {{DEFAULTSORT:Emd Dd35 Diesel–electric locomotives of the United States DD35 D-D locomotives Union Pacific Railroad locomotives Southern Pacific Railroad locomotives Railway locomotives introduced in 1963 Locomotives with cabless variants Scrapped locomotives Freight locomotives Standard-gauge locomotives of the United States