Изложена методика компьютерного проектирования прямозубых передач при переходе от однопарного к двухпарному зацеплению при сохранении неизменными: корпусных деталей, валов и посадочных поверхностей. Даны примеры синтеза 4-х передач, имеющих одинаковые размеры, но разную нагрузочную способность: две с коэффициентами перекрытия ε2. Приведена диаграмма для количественной оценки зависимости повышения нагрузочной способности передач с ε>2 в зависимости от сочетания чисел зубьев шестерни и колеса в исходной передаче. The technique of computer design of spur gears in the transition from single-pair to two-pair linkage is stated. While the case shaped parts, shafts and mounting surfaces remain invariable. The non-standard initial contour having parameters ha*=1.25, co*=0.20, α=20° was used in a technique basis. Quality of the designed gears is estimated by two criteria along all line of linkage: level of contact voltages according to Hertz and intensity of abrasive damage of teeth (coefficient of specific sliding). We created two diagrams for quickly to estimate prospects of replacement of single-pair engagement by the two-pair. The first diagram concerns dependence of overlap factor ε of the projected gear with ε2. The second diagram concerns quantitative assessment of increase of rated power P1 of gear upon transition from the optimized single-pair engagement to not optimized two-pair engagement (depending on a combination of numbers of teeth z1 and z2 in initial gear). We gave examples of synthesis of 4 transfers: having the same sizes, but different loading capacity: two to overlap factor ε2. The article, technique of synthesis and the developed program and methodical providing are focused on ordinary engineers, technicians and students.