This document describes the design of a mechanical hydraulic jack. It begins with introducing the basic principles of hydraulics and how hydraulic jacks work based on Pascal's law. It then discusses the design considerations and methodology for key components of the hydraulic jack, including the ram cylinder, plunger cylinder, plunger, lever, reservoir, and base. Detailed calculations are shown for sizing each component based on the design loads, pressures, and materials. Manufacturing and inspection steps are also outlined for the ram cylinder.