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.

The cars were designed in the first class range with side corridor and in the second class area with aisle. An abortion was available in Wagenmitte. The car was divided into two compartments of 6 resp. 5 first-class seats and the large-capacity compartment with 24 second-class seats. Panoramic windows on the side door side and twin windows are the special features for these cars.

Registration numbers: AB3 2394 - 2445

1932-34: 24 cars to B3 Nos. 323 ....
1930-34: 24 cars to C3 nos. 68 .... and 73 .... surrounding.
1930: 4 wagons to Z3p. from 1947 701-704