After the nationalization of the private railways had the SBB in their fleet a wide variety of car types, which were not up to the new requirements. Based on positive experiences with wagons with axles of 9.00 m, standards were set for the new types to be procured. For Nebenstrecken the biaxial second class carriages were included in the program.

For Nebenstrecken the three-axle car first class were included in the program. The cars were built as a side corridor and had cloth-upholstered seats. An abortion was present at one end of the wagon. The length of the leaf springs was set to 2.30m. The car was divided into four compartments of 6 seats each and the end compartment with 2 seats and additional side window on the boarding platform. Large panorama windows on the side door side are the special feature for this car.

Registration numbers: A3 511-525

1916: 15 wagons to B3 turn; Nos. 36 .... (from 1947 B3 8261-8275)
1924: 15 cars to C3 Nos. 74 ...