This apparatus consists of two standard epicyclic gear trains. Each gear train consists of a sun gear in the centre, three planet gears, a planet linkage and an internal or ring gear. The sun gear, ring gear and planet carrier all rotate about the same axis. The planet gears are mounted on shafts that turn in planet carrier and meshes with both the sun gear and the ring gear. Pulleys fitted with protractors are attached to the input and output shaft so that torque and velocity ratios may be determined.
Torques can be applied to the shaft by adding weights on cords wrapped on the pulleys. Bearings are used in the entire unit to minimize friction losses.
The apparatus can be operated in one a variety of modes. Locking pins are used to holding different parts of the apparatus in position. This gives the user different options on gear ratios that can be applied between the input and output shafts. By changing the combinations between the first and second epicyclic gear sets a wide range of ratios and different output directions can be produced. Efficiencies can be calculated for the units operation as well as theory tables given for the different gear combinations.