Servomotors from Pittman are available with integrated spur or planetary gearboxes in single and multistage models.
In general, spur gearheads are simpler and less expensive than planetary units and work best for low-torque applications. Torque capacity of spur types is limited because each gear in the train bears the entire torsional load.
Planetary gearheads, in contrast, share the load over multiple planet gears. Here, the input shaft drives a central sun gear which, in turn, drives the planet gears. Each of the planet gears simultaneously deliver torque to a rotating carrier plate coupled to a geared output shaft