This paper presents a novel 4 dofs (3T-1R) parallel redundant mechanism, with its complete study regarding inverse and direct geometric models (IGM and DGM), as well as singularity and workspace analysis. The robot is capable of performing a half-turn about the z axis (a complete turn would be theoretically possible if it were not for possible unavoidable inter-collisions in the practical case), and having all of its prismatic actuators along one direction, enables it to have an independent x motion - only limited by the stroke of the prismatic actuators. The mechanism is characterized by elevated dynamical capabilities having its actuators at base. Moreover, the performance of the robot is evaluated considering isotropy in velocity and forces.