Medication delivery pump

The present invention comprises a medication delivery pump that is configured to administer an infusion therapy using a medication delivery container. Medications in a flexible bag are expelled from the bag and delivered to an infusion site. A fluid delivery pump of the invention may have a constant force spring and a mechanical timer. The constant force spring is configured to compress a flexible fluid container. The mechanical timer assembly is coupled to the constant force spring and limits the maximum rate at which the spring compresses the fluid container. The pump may include first and second doors for charging the spring. Opening the first pump door partially charges the constant force spring and opening the second pump door fully charges the constant force spring. The pump provides improved administration of infusion therapy which is particularly advantageous for reducing errors, infections and other complications associated with manual infusion techniques.