SP M-4 #1673 is on display at the Southern Pacific Depot in Tucson, AZ

SP M-4 #1673, Tucson, AZ

#1673 is a Mogul type (2-6-0) M-4 Class locomotive built as a coal burner for the Southern Pacific Railroad in 1900 by the Schenectady Locomotive Works in Schenectady, NY, later part of Alco. A total of one hundred and three of the class were built for the SP between 1899 and 1900, the majority by the Cooke Locomotive Works in Patterson, NJ, with Schenectady providing just nineteen (#1615-#1618, #1629-#1631, #1673-#1674 & #1708-#1719).

As built, #1673 weighed 146,200 lbs, 123,700 lbs on its 63" drivers. It had 20" x 28" cylinders, a 168 sq ft firebox and total heating surface of 2,101 sq ft. Operating at a boiler pressure of 190 psi, it delivered 28,711 lbs tractive effort.

#1673 was based in Tucson, AZ, and operated primarily in southern Arizona hauling freight trains, logging over a million miles in service before retiring in 1955. It underwent several major overhauls and alterations during this period. In 1906, it was converted to a coal burner. In 1922, the locomotive was taken out of service for the addition of 269 sq ft superheating which, in turn, required replacing the slide valves with piston valves.


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SP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, Tucson
SP M-4 #1673, Tucson

The Stephenson valve gear was also replaced
with Walschaert valve gear. The upgrade
increased the engine weight to 157,900 lbs, 134,600 lbs on its drivers. The firebox area decreased slightly to 156 sq ft and overall heating surface dropped to 1,775 sq ft. Everything else remained much the same.

By the early 1950s, #1673 had been relegated to switching work and its original Vanderbilt tender had been replaced with a smaller square box tender. The engine's use further declined as the SP dieselised.

SP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, Tucson

Above, #1673 had a brief role in the 1954 film Oklahoma, for which it was fitted with a diamond stack and other turn of the century equipment.

By 1955, the engine  was seeing little use and mainly sitting in serviceable storage. That year, it featured in a publicity photo shoot in Sahuarita, AZ. It also featured that year in SP's 75th anniversary celebration in Tucson, AZ, hauling an excursion train from the SP Depot to the Pacific Fruit Express yard.

SP M-4 #1673, Tucson
SP M-4 #1673, TucsonSP M-4 #1673, Tucson

#1673 was presented to the City of Tucson in 1955 and went on display in front of the then Pioneers Historical Society, later the Arizona Historical Society.

In 1962, it was moved to Himmel Park and sat there for many years, exposed to the elements, gradually deteriorating and suffering periodic vandalism and theft of equipment, including its builder's plates and gauges.

SP M-4 #1673, TucsonSP M-4 #1673, TucsonSP M-4 #1673, Tucson

By the early 1990s, #1673 was in bad shape and facing disposal, but a group of volunteers, the 1673 Task Force, was formed to preserve the engine. In 1992, the locomotive was added to the National Register of Historic Places and, by 1994, it had been taken apart, sandblasted, cosmetically restored and reassembled.

In December 2000, the engine was moved out to the Southern Pacific Depot in downtown Tucson and, by 2002, a shelter and security fence had been erected around it. In 2005, it opened to public display following completion of restoration.

SP M-4 #1673, TucsonSP M-4 #1673, Tucson
SP M-4 #1673, Tucson

Since then, work has continued to repair and preserve #1673, including modifying the paint scheme to more accurately reflect how it appeared in the early to mid 1950s, painting parts such as the injectors and check valves red in keeping with SP practice.

Work has also been underway to clean, lubricate and reinstall parts removed during the 1992-1994 restoration but kept in storage, as well as finding or fabricating replacements for parts lost, stolen or damaged beyond repair during the many years of #1673's display.

The depot serves Amtrak's Sunset Limited and Texas Eagle services, and is next to an active Union Pacific line.

Below and right, UP GE AC45CCTE #7360, EMD SD70M #5166 and GE C40-8 #9213 heading north with a mixed freight.

UP GE AC45CCTE #7360, TucsonUP GE AC45CCTE #7360, Tucson
UP GE AC45CCTE #7360, TucsonUP EMD SD70M #5166, TucsonUP GE C40-8 #9213, TucsonUP GE C40-8 #9213, Tucson