View source for EMD DD35

{{Short description|American diesel-electric locomotives (1963–1981)}}
{{more footnotes|date=July 2016}}
{{Infobox locomotive
| name=EMD DD35
| powertype=[[Diesel-electric]]
| gauge={{track gauge|ussg}}
| image=UP SD45 and DD35.jpg
| caption=Two [[Union Pacific Railroad]] EMD DD35s sandwiched between a lead [[EMD SD45|SD45]] (#3638) and an unidentified trailing unit.
| builder=[[Electro-Motive Diesel|General Motors Electro-Motive Division]] (EMD)
| aarwheels=[[AAR wheel arrangement#D-D|D-D]]
| uicclass=Do’Do’
| primemover=Dual [[Electro-Motive Diesel|EMD]] [[EMD 567|16-567D3A]]
| builddate=1963–1964
| totalproduction=30
| locale=[[North America]]
| poweroutput={{convert|5000|hp|kW|-1}}
| maxspeed=
| locoweight=
| tractiveeffort=
| length=
| enginetype=[[two-stroke diesel engine|2 stroke diesel]]
| aspiration=[[Turbocharger|Turbocharged]]
| cylindersize={{convert|8+1/2|×|10|in|mm|0|abbr=on}}
| transmission=[[Diesel-electric transmission|diesel electric]]
| generator=[[Direct current|DC]] generator
| tractionmotors= DC traction motors
| locobrakes=[[Railway air brake|Straight air]], [[Dynamic braking (locomotive)|Dynamic]]
| trainbrakes=[[Railway air brake|Air]]
| buildmodel=DD35
| retiredate=1981
| disposition=All scrapped
}}
The '''EMD DD35''' was a {{convert|5000|hp|kW}} [[diesel-electric locomotive]] of [[AAR wheel arrangement#D-D|D-D]] [[wheel arrangement]] built by [[General Motors Corporation|General Motors]] [[Electro-Motive Diesel|Electro-Motive Division]] for the [[Union Pacific Railroad]] and [[Southern Pacific Railroad]].

==History==
In the early 1960s, Union Pacific started asking for a {{convert|15,000|hp|kW|-2|abbr=on}} 3-unit ''locomotive set'' to not only replace their [[Union Pacific GTELs|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]]) locomotive that consisted of two [[EMD GP35|GP35]] locomotives prime movers (engines) and electrical systems, mounted on a common frame back-to-back, riding on a pair of 4-axle [[Flexicoil truck]]s, 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 [[EMD DD35A|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&nbsp;hp GP35s sandwiching a pair of DD35s, to make one 15,000&nbsp;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 [[St. Louis - San Francisco Railway|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 [[EMD F3|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, Los Angeles|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 (railways)|sandbox]]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 [[wikt:teething troubles|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==
{| class="wikitable"
! Owner
! Quantity
! Numbers
! Notes
|- align = "center"
|[[Southern Pacific Railroad]]
|3
|8400-8402
|
|- align = "center"
|[[Union Pacific Railroad]]
|27
|72B-98B
|72B and 73B ex EMD (demonstrators) 5653 and 5655
|-
|}

==See also==
* [[EMD DD35A]]
* [[EMD DDA40X]]
* [[EMD DDM45]]
* [[ALCO Century 855]]
* [[GE U50C]]

== References ==
{{reflist}}

* {{cite book|author=Pinkepank, Jerry A.|title=The Second Diesel Spotter's Guide|publisher=Kalmbach Publishing Co., Milwaukee, WI|year=1973|isbn=0-89024-026-4}}
* {{cite web| last=Barris| first=Wes| url=http://www.steamlocomotive.com/centennials/| title=Union Pacific Centennials| access-date=January 11, 2005| website=SteamLocomotive.com}}
* {{cite web| last=Strack| first=Don| url=http://utahrails.net/webpubs/up-dd35.php| title=Union Pacific's DD35 Double Diesels| website=Utah Rails| date=December 8, 2007}}

{{UP Giants}}
{{EMD SDs}}

{{DEFAULTSORT:Emd Dd35}}
[[Category:Diesel–electric locomotives of the United States]]
[[Category:Electro-Motive Division locomotives|DD35]]
[[Category:D-D locomotives]]
[[Category:Union Pacific Railroad locomotives]]
[[Category:Southern Pacific Railroad locomotives]]
[[Category:Railway locomotives introduced in 1963]]
[[Category:Locomotives with cabless variants]]
[[Category:Scrapped locomotives]]
[[Category:Freight locomotives]]
[[Category:Standard-gauge locomotives of the United States]]