The attention was focused on the problem of frequently occurred failures of power supply elements (voltage stabilizers and relays of DC motors used in crane motion mechanisms. The analysis of this problem, carried out based on the monitored operational parameters and performances of the object, led to the straightforward conclusion that the failure frequency depends on the operational conditions such as the crane load and accelerations of the crane movement mechanisms. The mean values between failures of those operational parameters in and a (the crane load and acceleration respectively) were assumed as the input variables of the fuzzy predictive model