Infusion Pump

An infusion pump for controlled administration of a fluid contains a receptacle 4 for storing the fluid. The receptacle has a piston 6 and an outlet connected to a tube 12 for delivering the fluid. Propulsion means in the pump push the piston to deliver the fluid. A retaining means such as a cable is engaged with the piston to control its position and movement towards the outlet. A valve, which is biased to be closed, acts upon the tube to prevent passage of fluid. A rod (38, figure 10) actuated by tension in the retaining means opposes the valve bias to allow the passage of fluid. Also claimed is an infusion pump in which the propulsion means is two or more concentrically arranged helical springs having opposing directions of winding. Preferably, the retaining cable is metered from a spool (32, figure 9) by a motor (35) and worm gear in a gearbox (20). The distal end of the cable may be attached to braking arms 45 which deploy if the cable loses tension. The pump may comprise a pump body 2 and a cap 3, with the valve being disposed in the cap.