An injector for injection a fluid into a patient, including: a first pressurizing mechanism adapted to operatively connect with a first fluid container to pressurize fluid therein; at least a second pressurizing mechanism to operatively connect with a second fluid container to pressurize a fluid therein; a single drive; and a transmission to control how power from the drive is distributed to the first pressurizing mechanism of the first container and to the second pressurizing mechanism of the second container to control injection of fluid from the first container and from the second container. The drive can, for example, be an electric motor or other drive.