Although the SBB had taken over large numbers of the American four-axle coaches and the coaches had proven their worth in service, when ordering new vehicles it was decided to use a three-axle design. After some time, the long coach body showed a high level of warping and deformation. The reason for this was the very poor running properties of the primitive bogies without secondary suspension. Nevertheless, some remained in service until 1941 and trains formed solely with four-axle coaches of the same class still travelled between Winterthur and Wil in 1930.
