Scientific article perspective. Caterpillar armored vehicles remain a basis of the attacking forces of most armies, despite of a changeable combat situation. However the modern rigid methods of conducting of combat operations lead to increase of dynamical loads. In particular uses of additional armament and a guard of machines leads to increase in their weight and, respectively, loadings which reduce a longevity of caterpillars. Therefore the problem of a longevity of links of caterpillar chains, and other steel elements of designs of combat vehicles, is actual. As known that the elements of designs of combat vehicles, connected in the corresponding method, contact among themselves. In a time of a loading forces in them results from contact stresses and strains. Material in the place of contact, without having an opportunity to be deformed freely, is in volumetric stressed state. Contact stresses have local character and quickly decrease in accordance with a distance from a place of contact. However they can reach great values and cyclically change. Besides, contact interaction is followed by cracks near a contact zone. A friction on the surfaces of contact promotes acceleration of their chafing.The purpose. The purpose of the work is the research of distribution of contact stresses on width and depth of a plane of contact of steel elements of designs of combat vehicles taking into account a sliding friction on the surfaces of contact.Essence of researches, used methods. For research of contact stresses in the place of contact of the plane of a caterpillar link and effective area of the directing wheel, the model taking into account a frictional force is used. In that case on the surface of contact arise both normal and tangents stresses.It is built graphs of change of stresses in the center of the plane and on a surface of border of a plane of contact behind contact depth taking into account a frictional force. The equivalent stress in accordance with ІІІ theory of strength is determined and compared it with similar, however without a frictional force. In work elastic theory methods are used.The received results and conclusions. A stressed state in points of elements of designs with the contact depth is analysed in view of a frictional force on a surface. It is shown that the tangential stresses arise practically at the same distance of the contact depth, as well as without frictional force. However on a surface in the center of a plane of contact the equivalent stresses according to the III theory of strength will be larger almost for 15%, than the same stresses calculated without a frictional force. On borders of planes of contact on the surface of contact there will be stresses of stretch and stresses of press on borders of the site of contact. Therefore destruction of design elements and emergence of endurance cracks can begin not in the center, but on borders of a plane of contact. Besides, existence of the tangential stresses under the surface of contact causes shearing strains which are the reason of destructions of material of design elements from depth.Increase in external pressure at design elements of a caterpillar chain through an overload of contact surfaces and existence of cyclic-variable dynamic capacity predetermines emergence in material of a volume stressed state with the equivalent stresses, which can exceed limit of endurance. At a particular depth from the surface of contact microcracks arise and grow. Over time these microcracks expand, come to a surface, causing a spalling and chunk-out of material.