Abstract: The response of hydropneumatic suspension in vehicles regarded as having two - degrees of freedom is discussed applying the theory of nonlinear random vibrations . The formulae for the means and variances are given . It is pointed out. in this paper that.a system will have non-zero mean response under zero mean excitation . This conclussion has not been arrived at in the paper by Lin Yaoqun and other . Also discussed the variations in means and variances with variable excitations .