Union Pacific DD35 and DD35A

Author: John Oxlade, Salfords, Surrey, UK (EMail: )

Prototype information:

DD35 #73B

Although the Union Pacific asked EMD, GE and ALCO to design 3 locomotive sets of approx. 15000hp, EMD instead chose to offer a special DD35 booster, to run in pairs between two GP35s (i.e. a 4 loco set). EMD took their then standard GP35 and essentially mounted two of the car bodies (without cabs) on a common chassis. Unlike GE and ALCO's offerings, EMD chose to design a new D (4 axle) truck specifically for this locomotive.

EMD planned to sell the DD35 with GP35s as the control units on either side, though any loco with MU capability could (and often was) used. EMD built two DD35 demonstrators in November 1963 and along with a pair of GP35s painted in a striking red and white livery (similar to the Frisco scheme). These toured several Class I railroads looking for potential buyers. In the end only the Union Pacific and Southern Pacific bought DD35s. UP bought the two demonstrators (along with the GP35s) and another 25 DD35s, the SP bought only 3.

The 2 demonstrators were bought by the UP in June 1964 and numbered 72B and 73B. 74B arrived in May 1964 with production running through to September 1964 when the last, 98B, was delivered. (Note: The delivery of 80B resulted in the UP's experimental coal-burning turbine being renumbered from 80 to 8080 in April 1964 to make space. As far as is known the coal-burning turbine never ran with the number 8080 as it was already in storage at this time.)

DD35A #75

At its inception, EMD considered the DD35 to be purely a booster. The UP was pleased with the performance of the units and in 1965 turned to EMD to request a version of the DD35 with a cab. The new loco was identified as a DD35A. (Note: Original EMD documentation calls the B-unit a DD35 not a DD35B.) Apart from having a standard 35-series cab as fitted to contemporary GPs and SDs, the new DD35A also incorporated the new flared radiators that were being tested on the 645-series test-bed locos (i.e. the prototype SD40s #434A-434E). UP received 15 DD35As between May and July 1965.

Early in their careers the DD35s suffered from poor electrical reliability. It was suspected that sand from the internal sandboxes was getting in to the switchgear and new sandboxes were mounted on the walkways. This seems to have resovled many of the electrical problems, but as time moved on, they became quite "old fashioned". The DD35s did not having any form of anti-wheel-slip, and they were also the last EMD locos (along with the GP35s) to have DC generators.

The DD35s performed well all over the UP and were found in multiple with many other diesels (and not just UP either). It was quite normal to have a DD35 running behind a U50. The units were worked hard throughut the 1970s and with the arrival of newer units in the late 70s the B-units were put to one side in 1979. The downturn in the economy in the early 1980s started the withdrawl of the A-units, and all of the DD35s were off of the UP roster by 1981. In their final months of service, the DD35s were mostly used around Salt Lake City so that they were kept close to the repair shops there.

No DD35s have been preserved.

Footnotes:

• Unit 82 was equipped with RCS Control equipment, with unit 82B equipped as the RCS Remote unit from May 1968 to July 1973.
• Units 71, 81B and 86B were fitted with Performance Control equipment and could run at a continuous minimum speed of 11mph.
• Large external sand boxes were added to all DD35s in 1969. These large boxes were fitted on the edge of the frames in line with the handrails. They were fitted front and back on DD35s and at the rear only on DD35As.

Model information:

Hobby-quality

Unfortunately no hobby-quality models of the DD35 or DD35A have been made. Athearn do however produce a model of a DD40. This was patterned after a model that EMD offered but never actually built so will always be an approximation. It is also one of Athearn's older "too-wide-hood" models. It would be possible to build a representation of a DD35A from one of these, though the work involved would be considerable. Contrary to the title, the article "Modeling the Centennials -- Union Pacific's Famous 6900's" (listed in the references below) describes how to build a DD35A from Athearn's DD40.

Modelling a DD35 should be possible by combining 2 Rail Power Products GP35 shells with a scratchbuilt chassis and Athearn D trucks. It would not be an easy kitbashing exercise, but most of the components are fairly easily available and it would make an unusual model.

Collector-quality

Brass DD35s have been imported by ALCO and Overland (and perhaps others). Overland locos run well and have good detailing but are expensive. Though not especially good runners, ALCO models have generally good detailing and will stand up to inspection at normal operating distances. North West Short Line (www.nwsl.com) produce replacement gears and universal-joints (along with new motors) that can be used to upgrade the mechanism of an ALCO model.

ALCO Models DD35	Overland Models DD35A

References:

Carter, Brian, and Carter, Charles. "Modeling the Centennials -- Union Pacific's Famous 6900's." Railroad Model Craftsman, November, 1994, pp. 77-83. Cockle, George R., Giants of the West, Overland Publications, Muncie Indiana, ISBN 0-916160-12-2

[ last updated 31st Dec 2003 ]