Effect of outlet pressure (pressure) flow of oil from the hydraulic resistance on the discharge coefficient (conductivity) of the individual throttle element is essential, as noted in the literature. Simultaneously, the authors indicate that the size and behavior of the flow depends on the geometry, but this feature of throttling element is not explained in the literature. Studies have shown that the flow coefficient (resistance) and its behavior in the presence of back pressure should be determined on the basis of experimental flow characteristics - dependence of flow on the difference of pressure and rpodmin rpodmax on existing throttling element by contraction. Construction of flow characteristics in logarithmic coordinates the average discharge coefficient in the range of flow (pressure drop) available in the throttling element is determined. Further calculations should be based on standard formulas.