Reading Company C1a Class

P&RR C1a class
Reading No. 110, as built
Type and origin Power type Steam Builder Reading Company Build date 1915 Total produced 4
Specifications Configuration: ​  • Whyte 4-4-4 Gauge 4 ft 8+1⁄2 in (1,435 mm) Driver dia. 6 ft 8 in (2.032 m) Loco weight 230,800 lb (104,700 kg) Fuel type Coal Boiler pressure 240 psi (1.65 MPa) Cylinders Two, outside Cylinder size 23.5 in × 26 in (597 mm × 660 mm)
Performance figures Tractive effort 36,604 lbf (162.82 kN)
Career Withdrawn 1916

The C1a Class were a type of 4-4-4 steam locomotive built for the Philadelphia and Reading Railway in 1915. Four locomotives were built, road numbers #110-113. They used front and rear trucks that were effectively identical. During a year of operation, they proved to be quite unstable; after that year, they were rebuilt to 4-4-2 "Atlantic" locomotives, reclassified as P7sa, and renumbered #350-353.