Reliability is the objective characteristic of normal functioning under the safety of operation of the element of load-lifting equipment. Reliability value is used to decide on the operation of the component, its strengthening or prohibition of exploitation. The residual resource of the structure determines the timely repair or termination of the operation. Prediction of residual resource, i.e. estimation of reserve of proper operation, is the main indicator determining reliability, as well as the most important element in the system of management of the technical condition of load-lifting cranes and its structural elements in operation. Deviation of values of diagnostic parameters beyond the permissible limits, caused by component various damages in the components of the mechanism, serves as a basis for deciding to carry out the necessary technical actions to restore operability. The method described in this article is based on the principle of fuzzy sets, which makes it possible to take into account the factor of uncertainty of operating conditions. A fuzzy value of the residual resource is defined in the form of an interval \([{T}_{pes}; {T}_{opt}]\) , where \({T}_{pes}\) and \({T}_{opt}\) are the values of the residual resource for the pessimistic and optimistic options, respectively, which allows to assess the degree of confidence in the new assigned service life and thus manage the risks arising during operation.