###### Abstract  
Aerostatic bearings are attractive, with minimal friction losses, high durability, and environmental friendliness. However, such designs have a number of disadvantages, including low load-bearing capacity and high compliance due to high air compressibility and limited injection pressure. The article proposes a double-row aerostatic journal bearing with an external combined throttling system and longitudinal microgrooves in the inter-row zone. It is hypothesized that the use of microgrooves will reduce the circumferential flows of compressed air, as a result of which the compliance should decrease and the bearing capacity should increase. To test the hypothesis, we carried out the mathematical modeling, calculations, and theoretical study of stationary operation modes of the bearing for small shaft eccentricities in the vicinity of the central equilibrium position of the shaft and bearing capacity for arbitrary eccentricities. Formulas were obtained for the numerical evaluation of compliance for bearings with a smooth bushing surface and with longitudinal microgrooves. Iterative finite-difference methods for evaluating the fields of the squared pressure are proposed, on the basis of which the load capacity of the bearings is calculated. Experimental verification of the bearing's theoretical characteristics was carried out, which showed satisfactory agreement between the compared data. The study of the compliance and load capacity of a microgroove bearing yielded impressive results. We show that the positive effect from the application of the improvement begins to manifest itself already at four microgrooves; the effect becomes significant at six microgrooves, and at twelve or more microgrooves, the circumferential flows in the bearing gap practically disappear; therefore, the bearing characteristics can be calculated on the basis of one-dimensional models of air lubrication longitudinal flow. Calculations have shown that for a length of \(L=1\), the maximum load capacity of a bearing with microgrooves is 1.5 times higher than that of a conventional bearing; for \(L\geq 1.5\), the bearing capacity increases twice or more. The result obtained allows us to recommend the proposed improvement for practical use in order to increase the load capacity of aerostatic journal bearings significantly. a aerostatic journal bearing; compliance; load capacity; longitudinal microgrooves 2021 11 5  
At the same time, aerostatic bearings have a number of disadvantages, the most predominant of which are low load-bearing capacity, high compliance (low stiffness), and an increased tendency for instability. The first two drawbacks are explained by the limited injection pressure, and the last drawback is determined by the high compressibility of air, even in microvolumes [17; 18]. To reduce compliance, aerostatic bearings are used with active compensation of airflow and with displacement compensators of the movable element (shaft) [19; 20; 21; 22; 23; 24]. In such bearings, the problem of high compliance is solved because these types of bearings allow a decrease in compliance to zero and even negative values (in the latter case, the shaft relative to the housing is displaced in the direction opposite to the current load), which allows the structures to be used not only as supports but also as active deformation compensators of the technological system of machine tools in order to reduce the time spent and increase metalworking accuracy. A constructive innovation--the system of external combined throttling (SECT) [18]--provides a significant decrease in compliance and guarantees stability. The use of SECT can significantly increase the performance speed of bearings and improve their dynamic quality, significantly reducing the oscillation of transient processes caused by external forces, which also affects the accuracy of metalworking. Progress towards improving compliance and stability characteristics has not, however, touched on one of the main performance characteristics of aerostatic bearings, namely, their bearing capacity.