Abstract :
A simple mathematical model of a machine aggregate is derived and some of its dynamic properties are studied at periodic loading. The aggregate is composed of a finite power Diesel drive, a hydrodynamic power transmission, a mechanical gearing and a working machine. At mathematical modelling of the hydrotransmission, it is started from experimentally measured external static characteristics. The mathematical model has the form of a combined system of non-linear differential and algebraic equations. The stationary solution is looked for by a modified method of harmonic balance.