Described herein are medical fluid infusion systems for pumping a fluid to a patient, such as in a hospital environment. In one aspect, disclosed is an infusion system including a drive assembly having a drive fluid reservoir and a drive mechanism configured to apply a force to drive fluid from the drive fluid reservoir through a length of tubing. The infusion system includes a hydraulic assembly having a first fluid chamber having an inlet port configured to be in fluid communication with the length of tubing and a second fluid chamber having an outlet port configured to be in fluid communication with a patient extension set and a flexible movable divider sealing the first fluid chamber from the second fluid chamber. Related apparatus, systems, techniques and articles are also described.