GBX planetary gearbox, 32:1 reduction
The GBX1200320703D is a Schneider Electric planetary gearbox with straight-cut teeth, a 32:1 single-stage reduction, and a Ø 120 mm housing that drops straight onto a servo or stepper motor mounting flange. The GBX family is sold on a 12 arc.min maximum backlash figure, so it is positioned for positioning axes where repeatable return-to-position matters more than the headline ratio. Continuous output torque is rated 260 N.m, with a 416 N.m peak ceiling for accelerating or shock-loaded duty, and the design life is sized for 30000 h at 100 rpm at 30 °C — the duty envelope an integrator should size against, not the peak number on the brochure.
Shaft load envelope and bearings
Maximum radial load on the output shaft is 1500 N at 100 rpm over the full 30000 h service life (2000 N if the application only needs 10000 h), and the maximum axial load is 2100 N under the same envelope (2800 N at the shorter life rating), force applied at mid-distance from the output shaft. The values are derated together — an integrator running higher than 100 rpm must pull both the Fa and Fr curves off the datasheet before sizing the coupling. Moment of inertia at the input is 1.3 g.cm², which keeps reflected inertia low for small-frame servo motors; the output shaft is C 45 medium-carbon steel, and the housing is black anodized aluminium — lightweight enough for moving carriages without giving up the heat-sinking a continuous-duty gearbox needs.
Precision, stiffness, and operating envelope
Torsional rigidity is 13 N.m/arcmin and maximum torsional backlash is 12 arc.min — paired numbers an automation engineer reads together: the gearbox will wind up under load by a predictable amount, but the unloaded return-to-position is repeatable enough for indexing and pick-and-place. Mounting position is unrestricted (any position), so the unit can be oriented to suit the machine envelope rather than the other way round. Operating ambient temperature spans -25 °C to 90 °C, and efficiency is rated 94 % on this size — meaning most of the motor power reaches the load and the gearbox does not need an external cooler inside the rated envelope. Noise is 65 dB measured at 1 m with the unit running no-load, the figure an integrator uses for cabinet-noise budgeting rather than the loaded operating figure.
Sealing, lubrication, and on-machine integration
The shaft seal carries an IP54 rating at the output, which covers dust ingress and splashing water but is not a washdown rating — an integrator specifying it for food-and-beverage lines or outdoor equipment should treat that as a placement constraint and add guarding. Lubrication is filled for life, so the unit ships ready to mount with no scheduled grease interval inside the 30000 h service window at 100 rpm / 30 °C.