Northwestern Pacific Railroad Network

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At least a few of these visited the NWP, so I compiled this info on them. 

(Also: If anyone knows how to reach My Espee Modeller's Archive, I would be more than willing to send them this info. I have tried, but it never reaches through their email.)

(MU means Multiple Unit Control)

SP AS-616:

Delivered in two batches, 5228-5249 and 5250-5278.

The first order is distinguishable by the cast frame instead of welded frame; the side sills are smaller than other units. They came equipped with dynamics, high mounted bells and numberboards. They were painted in “Tiger Stripe”.

The second order came with all of the goodies the first order had, but with a welded frame instead of the cast frame. Again, distinguishable by the “fatter” side sills and the cuts in the frame for the trucks to swing out farther (the cut is where the air reservoir for the brakes is on the truck).

While Baldwin was building the second batch, SP ordered concurrently the AS-616B’s and so a few of the AS-616’s in this number series were equipped with MU. Due to Baldwins build style (one engine at a time - like steam locomotives), the MU units were spread out among the entire 5250-5278 number system.

Shortly after arrival, the units with MU capability were given large “trash can” Mars lights on each end. This included fabricating a steel polygon that peaked at the Mars which continued the (very minimal) curvature of the hood. The bell on these were also moved to below the frame.

The MU capable units (with their matching AS-616B’s) were sent to the Northwestern Pacific, with a few stops in between to test the beasts at other locales. Eventually they migrated to Oregon before returning south to work California’s humpyards.

Some AS-616's were sent to Pacific Electric, gaining “Pacific Electric” lettering and trolley poles to work with Pacific Electric's crossings. This was likely very short lived, the AS-616's were barely scraping past the PE's weight limit…

Despite the fact that they were built for road service, they were used extensively at hump yards. Assignments were almost always switching around West Colton, Taylor and Roseville before being replaced by Century series units (which had been rebuilt at this time) in 1970.

Around 1965, when units came in for large maintenance, the shops lowered their gear ratios from 63:15 to 68:15, increasing tractive effort at the expense of speed (This usually came when the unit required heavy maintenance.) Not all got the ratio change, some staying almost entirely stock until the very end. Units that were sent in got repainted into Bloody Nose.

After the ratio change, the units were sent back to the humpyards at West Colton, Taylor and Roseville (with the DRS-6-6-1500 A/B’s, DRS-6-4-1500’s, and AS-616B’s). Not all got Bloody Nose, some keeping Black Widow well into 1969.

SP seemed to be very confused by these units, as photos of them show both the Bloody Nose switcher scheme and the Bloody Nose road scheme (with wings) on different units…

As with all SP light package-less Baldwins some were given small rotary beacons on the cab roof.

By 1966, there were only 34 on the roster, almost all the disappearing ones going to shortlines. Only 18 were still on the roster by 1967. All were written off after the removal of 5233 in 1971.

One interesting note (other than the number) was that the Baldwin’s were kept alive well past their builder’s life, mainly because of the replacement parts business…

A few select Baldwin employees kept making renewal parts for Baldwin-Lima-Hamilton diesels well into the 1990’s. Baldwin had two options for the AS-616’s gear ratio; 63:15 and 68:15 (written as 15:63 and 15:68 in the Baldwin archive). As such, the ratio change could be done by replacing the gearbox, thus extending the life of the engine.

Three still exist: 5274, 5253 and 5249.


SP DRS-6-6-1500:

Delivered in two (?) batches.


The first (from March 1949) came with cast frames, high mounted bells, and numberboards, numbered 5203-5210. The second (from December 1949) had welded frames and all the goodies of the first order (numbered 5211-5226). Dynamics came on the second order only.


These were bought for Oregon (like almost all the SP Baldwin road switchers) but they eventually migrated the Central Valley and Southern California. They were used for switching at Roseville and West Colton, as well as locals out of West Colton into Hollywood.


Some DRS-6-6-1500's were sent to Pacific Electric, gaining “Pacific Electric” lettering and trolley poles to work with Pacific Electric's crossings. They were returned to SP soon after.


Their paint system was pretty standard; all units were delivered with Tiger Stripe, then they were repainted with aluminum hood ends, then they were given Black Widow, before a select few still on the roster finished their days in Bloody Nose.


They had minimal upgrades over the years, the most extensive being the movement of the radiator upwards (as it was on the AS-616). Along with this modification, came an upgrade of the gearing from 63:15 to 68:15 ratios. Units that were upgraded were varied; some kept the original radiator grille but gutted, while some had it plated over.


The entire number series wore Black Widow, despite being classified as (and being used as) switchers.


As with all SP light package-less Baldwins some were given small rotary beacons on the cab roof. I don’t know which ones had them, but some digging could bring up one or two…


None were assigned a 1965 number, as they were to be removed from the roster by 1966.


Only one is preserved: 5308, at the California State Railroad Museum (being one of only two preserved DRS-6-6-1500’s).


As with all SP Baldwin road switchers, the paint shop was very confused by these units, with most gaining the Bloody Nose switcher scheme, but some got the Bloody Nose road scheme. This was likely fixed shortly after this blunder.

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Comment by Ian B. on March 25, 2018 at 10:52pm

MU means Multiple Unit Control. It is a way of controlling multiple engines at once. EMD, ALCo, GE, Baldwin, and Fairbanks Morse all use the term "MU" to denote whether or not a unit can control a second unit behind (or in front of) it. MU is "cross-compatible" with all builders, but Baldwin's throttle mechanism did not comply with the throttles of ALCo, Fairbanks-Morse, GE and EMD.

Comment by Richard C. Brand on March 25, 2018 at 10:44pm


You use the acronym "MU" frequently but don't explain reference connotation.  What is  MU?

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