The following paper reviews all the possible cases of coupled two-carrier planetary gears with four external shafts. An emphasis is made on the work of these gears with one degree of freedom, one input and one output shaft and brakes on the other two shafts . When switching over the gears, the speed ratio of the gear is changed, thus allowing the use in two-speed mechanical transmissions of technological lifting and other machines. Some relations are deduced for determining the speed ratios and the efficiency of all structural schemes.
Recommendations for the selection of the most appropriate structural scheme according to the current necessities can be made. A 3D model of the S13V3 two-speed, two-carrier gearbox was created to demonstrate the process of determining the viability of a particular gearbox layout.