| SP PA1 6006, Ogden Utah, October 3, 1958, photographer unknown, Chuck Zeiler collection. Sometimes mistaken for a PA3, a model never built by Alco, this locomotive was built as a PA1 in 1948. Due to renumbering in 1949, my best guess is that 6006 was built as 6005C. The following is from the book, A Centennial Remembrance, by Richard T. Steinbrenner (c.2003, On Track Publishers, ISBN: 0911122-07-9): The SPs Pacific Lines basic acquisition policy of A-B-A sets continued to be followed with the PA-2/PB-2 orders. Alco delivered two sets in August-September 1950. By then the SP was using a new numbering system; the PAs continued in the 6000 series, and the PBs were numbered in the 5900 series. The PA-1/PB-1s numbered in the 6000 A-B-C sequence were renumbered into the new scheme, as were the subsidiaries PA-1 units. The SP came back for two more sets in April 1952, and then, in Alcos last big order for PA/PBs, for two batches, which were delivered in June-July and September-October 1953. The first batch was three sets of the usual A-B-As, but the second batch of 12 units was all PAs, equipped with standard Alco pilots. For most of their careers, the SPs Pacific Lines PA/PBs were assigned to the West Oakland Shops for maintenance although for a while seven of the final units were assigned to Taylor Yard in Los Angeles for Coast Line service to San Francisco. While the PA/PBs also operated on the San Joaquin Division on occasion, their principal assignments were on the Shasta Daylight and Cascade trains between San Francisco-Oakland and Portland, OR, and on the Overland route between Ogden, UT and San Francisco-Oakland. Beginning with the 1952 deliveries, the PA-2s came from Alco without pilots, enabling the SP to apply its own design snowplow pilots, built at the Sacramento Shops. The 1953 units incorporated the Model 244G prime mover, which included the new water-cooled turbochargers (Alco Model 710), and had distinctive stainless steel moldings around the windshields. In the meantime, maintenance costs of the 1948-49 PA-1/PB-1s had become problematic, and from July 1952 to March 1953 the West Oakland Shops replaced all their prime movers with 2250 hp Model 244Ds at the rate of four units per month. With the completion of the program, all the SP units were essentially PA-2/PB-2s. In 1956 the SP undertook a modernization program to encompass its entire PA/PB fleet. The prototypes were six high mileage units, which were stripped down to the frame and truss supports, then sandblasted down to bare metal. With GEs guidance, the SP had designed a new electrical equipment cabinet, greatly modernized and simplified. The new cabinets were preassembled and installed into the frame and truss from overhead. All of the previous wiring that snaked through the underframe was replaced and run in the engineroom overhead in troughs for ease of maintenance. Plug electrical connectors were replaced by screw connector blocks for greater reliability. The control equipment was upgraded and repackaged into compartments that featured greater accessibility. The first unit through was #6021, and by June, a three-unit set was ready for road testing. The Sacramento Shops proceeded to rebuild the entire PA/PB fleet in this manner. Externally, the most obvious effect of the upgrade was the application of Farr-Aire grills to all units that did not already have them (Alco had phased in the application of the Farr-Aire grills on the last order for 18 units to the MP in June-July 1952, which eliminated the PAs signature drip strip and horizontal slatted carbody grill). However, on the SP units, the Farr-Aire grills were not continuous along the side; rather solid panels were fixed between the grill sections. |