NFLShop.com - NFL Jerseys and Gear
Enter the Classic Streamliners Bookstore.
Shop for Trains and Railroad Collectibles on eBay
Shop for Railroad and Train Collectibles on eBay
Enter the Classic Streamliners Bookstore.
NFLShop.com - NFL Jerseys and Gear

Classic Streamliners - TRAIN​CYCLOPEDIA

Historic Rail - Shop Now!

Southern Pacific AC-4 No. 4100 and crew.

Baldwin logo.
Southern Pacific AC-4 No. 4100 and crew.
SP herald.

Southern Pacific Class AC-4 Articulated Consolidation Cab Forward Steam Locomotive
Southern Pacific Railroad's AC-4 class of steam locomotives were the first class of 4-8-8-2 cab forward locomotives. They were intended to improve on the railroad's MC class 2-8-8-2 locomotives with a larger firebox.

The AC-4s were the first SP Mallets built for simple expansion. Baldwin Locomotive Works built them in August through October of 1928 with a maximum cutoff of 70%, so tractive effort was rated at 112,760 lbf (501.6 kN); a few years later limited cutoff was dropped and calculated tractive effort increased to 116,000 lbf (520 kN).

The AC-4s were removed from service starting in 1953 and all ten were scrapped by June 1955.

Southern Pacific class AC-4 Overview
Type and origin
Power type: Steam
Builder: Baldwin Locomotive Works
Serial numbers: 60575, 60576, 60623-60625, 60666-60669
Build dates: August–October 1928
Specifications
Configuration: 4-8-8-2
Gauge: 4 ft 8 1⁄2 in (1,435 mm) standard gauge
Driver diameter: 63 in (1,600 mm)
Adhesive weight: 475,200 lb (215,500 kg; 215.5 t)
Loco weight: 614,600 lb (278,800 kg; 278.8 t)
Boiler pressure: 235 psi (1.62 MPa)
Feedwater heater: 4¼-BL Worthington
Cylinder size 24 in × 32 in (610 mm × 813 mm) (bore × stroke)
Performance figures
Tractive effort: 112,760 lbf (501.6 kN), 116,900 lbf (520 kN) rebuilt

Career
Operator: Southern Pacific Railroad
Class: AC-4
Number in class: 10
Numbers: 4100 – 4109
First run: October 1928
Disposition: scrapped

See also:

Cab Forward Locomotives

4-8-8-2 Locomotives

Steam Locomotives

Baldwin Locomotive Works

Locomotives