Planetary gearbox, 120 mm, 4:1 — torque and stiffness numbers
The GBX1200040844D is a straight-tooth planetary gearbox in the 120 mm diameter frame, delivering a 4:1 reduction ratio. Continuous output torque is 155 N.m, with a maximum intermittent rating of 248 N.m — the gap between those two numbers is the thermal limit under sustained load, not a mechanical ceiling. Torsional rigidity is 12 N.m/arcmin and the maximum backlash is 8 arcmin. For a positioning axis, that stiffness number tells you how much wind-up you get under load — at 155 N.m continuous you're looking at roughly 13 arcmin of twist across the gear train before the load moves.
Efficiency, noise, and the load-life envelope
Rated 96 % efficiency — that's the power loss through the gear train at rated torque and speed. The 65 dB noise level at 1 m, no-load is a bench figure; expect a few dB higher under load, but it's still in the quiet range for a planetary stage of this size. Service life is 30,000 hours at 100 rpm and 30 °C ambient. The maximum axial force on the output shaft is 2100 N at that duty point, and maximum radial force is 1500 N applied at mid-shaft. If you push the speed or temperature, those numbers derate — the 10,000-hour figures (2800 N axial, 2000 N radial) give you the short-term overload boundary. The shaft output carries IP54 protection, so it handles dust and splashing water but not washdown.
Construction and sourcing
Housing is black anodized aluminium; the output shaft is C45 steel. Mounting position is any orientation, which simplifies layout in a crowded panel or machine frame.