This paper concerns with the development of three nonmotorized individual lower limb joints rehabilitation mechanisms based on a four-bar linkage, and mechanical movement transmission from the motion of the patient’s upper limb. Initially, mathematical and computational models are built based on the desired angular motions for the hip, knee, and ankle. A prototype for the knee mechanism was constructed for initial experimental tests. The first test with wooden mannequin show that this prototype is lightweight, has an output movement compatible with the amplitudes, is easy to build and operate, being thus ready for clinical tests with healthy and impaired subjects.