ABSTRACT: In this paper, the forced three-dimensional vibrations of a machine unit mounted on the wagons of the electric modular trains are studied. The unit is suspended on three vertical supports to the wagon frame. A vibrating isolation assembly is constructed at the top end of each carrier. The unit is accepted as an ideal rigid body. The bearers along with the vibrating insulating knots are considered to be perfectly elastic and immaculate. The first stage of this study was carried out, and it involved the task of determining Eigen frequencies and Eigen forms. The present work is a second stage and is related to the study of forced vibrations of the same aggregate. They arise from the unbalanced masses and the inertial forces generated by the piston compressor operating cycle. The paper shows the mathematical model of the unit and the differential equations in the matrix form describing the small three-dimensional forced vibrations. The main objective of the study is to identify damping in the system. It consists of three vibrating insulating units consisting of successively and in parallel working rubber shock absorbers and metal connecting elements. Recordings of hysteresis curves obtained from laboratory tests of exploited and new dampers were used. For each vibrating isolator, the absorption coefficient is determined, followed by the damping coefficients.