The planetary gear is a special type of gear drive, in which the multiple planet gears revolve around a centrally arranged sun gear. The planet gears are mounted on a planet carrier and engage positively in an internally toothed ring gear. Torque and power are distributed among several planet gears. Sun gear, planet carrier and ring gear may either be driving, driven or fixed. Planetary gears are used in automotive construction and shipbuilding, as well as for stationary use in turbines and general mechanical engineering.

The GL 212 unit allows the investigation of the dynamic behaviour of a two-stage planetary gear. The trainer consists of two planet gear sets, each with three planet gears. The ring gear of the first stage is coupled to the planet carrier of the second stage. By fixing individual gears, it is possible to configure a total of four different transmission ratios. The gear is accelerated via a cable drum and a variable set of weights. The set of weights is raised via a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight has been released. The weight is caught by a shock absorber. A transparent protective cover prevents accidental contact with the rotating parts.

To be able to determine the effective torques, the force measurement measures the deflection of bending beams. Inductive speed sensors on all drive gears allow the speeds to be measured. The measured values are transmitted directly to a PC via USB. The data acquisition software is included. The angular acceleration can be read from the diagrams. Effective mass moments of inertia are determined by the angular acceleration.