Gearbox specs that determine the fit
The GBX1200080551F is a straight-tooth planetary gearbox, 120 mm diameter, with an 8:1 reduction ratio and 8 arc.min maximum torsional backlash — a precision class that matters for positioning applications where cumulative angular error stacks across multiple stages. Continuous output torque is 120 N.m at 100 rpm and 30 °C ambient; the peak (maximum output torque) hits 192 N.m under the same conditions, giving roughly 60 % overload headroom for starting or transient loads. Rated service life is 30,000 hours at 100 rpm and 30 °C — the axial and radial force ratings (Fa 2100 N, Fr 1500 N) are also quoted at that life target. Push the duty cycle or ambient temperature and the life drops; the 10,000-hour ratings (Fa 2800 N, Fr 2000 N) show the trade-off.
What the 94 % efficiency means on the line
At 94 % efficiency, the gearbox loses about 6 % of the input power as heat. For a 120 N.m continuous output at 100 rpm (~1.26 kW mechanical), that's roughly 75 W dissipated inside the housing — well within the capacity of the black anodized aluminium body, but worth factoring into the thermal budget if the gearbox is enclosed in a sealed cabinet. The shaft output carries an IP54 rating — protected against dust ingress and splashing water, but not submersion or high-pressure washdown. The rest of the housing is sealed by the anodized aluminium; the lubricated-for-life grease is captive, so no maintenance access ports to leak.
Sourcing this obsolete planetary gearbox
Schneider Electric lists the GBX1200080551F as obsolete. The part is lubricated for life and sealed — no field rebuild path — so replacement is a straight swap of the same unit or a parametric cross. Sourced through independent distribution against an RFQ. No stock-holding claim — every order is quoted to the BOM line.