A cylindrical drift chamber with ″bicycle-wheel″ geometry has been constructed as the central detector for the Axial Field Spectrometer (AFS) at the ISR. To permit particle separation in jet-like events at high event rates, a considerable degree of azimuthal segmentation was chosen with up to 42 space points per track. These points are obtained from measurements of drift time and charge division. Some particle identification is achieved with ionization loss sampling (dE/dx). This contribution presents details on the construction and the operation of the drift chamber at the ISR and preliminary performance results.