A device for delivering fluid to a patient, comprising: an exit port assembly a reservoir including a side wall extending towards an outlet connected to the exit port assembly a threaded lead screw received at least partly in the reservoir and extending towards the outlet a plunger secured to the lead screw and having an outer periphery linearly slideable along the side wall of the reservoir, wherein the plunger and the lead screw are operatively arranged such that rotating the lead screw in a first rotational direction causes the plunger to slide along the side wall towards the outlet of the reservoir a gear secured to the lead screw and including radially extending teeth a moveable pawl assembly including, a cage coaxially arranged with respect to the lead screw about the gear, the cage linearly movable in opposing first and second linear directions, a first pawl extending from the cage and biased against the teeth of the gear, wherein the first pawl and the teeth are shaped and oriented such that the first pawl rotates the gear in the first rotational direction during linear movement of the cage in the first linear direction but causes no rotation of the gear during linear movement of the cage in the second linear direction and wherein the first pawl prevents rotation of the gear in an opposite second rotational direction, and a second pawl extending from the cage and biased against the teeth of the gear, wherein the second pawl and the teeth are shaped and oriented such that the second pawl rotates the gear in the first rotational direction during linear movement of the cage in the second linear direction but causes no rotation of the gear during linear movement of the cage in the first linear direction and wherein the second pawl prevents rotation of the gear in the opposite second rotational direction.
