Influenza like pandemics are a severe threat to any established health care system as many thousands of patients would need emergency ventilator support during the acute respiratory failure stage, and this quickly overloads the existing facilities. The present article addresses the design and development of a human breathing assist machine (ventilator) prototype for use by qualified medical professionals in the emergency room, as well as in other locations, where a regular ventilator machine cannot be made available. The ventilator has been designed using readily available locally sourced materials, which can be assembled in a short time. This ensures the minimum required features to ventilate a patient in emergency conditions. The popular crank-rocker mechanism has been used to meet some of the vital design requirements of the emergency ventilator. The size of the links has been chosen to maintain a fixed inspiratory-to-expiratory (I:E) time ratio of 1:2. The kinematic linkage design has been kept modular by introducing a feature to adjust the location of the rocker tip to control the tidal volume from 100 ml to 600 ml of oxygenated air per breath. A virtual CAD model, based on the above-mentioned linkage design, has been designed to assess the variation of the position and velocity with time. Finally, a working prototype has been made, and it was observed that the I:E time ratio of 1:2 was achieved satisfactorily.