of torque ratings for different gear reducer sizes or ratios?

In the context of industrial engineering, a torque of 1,558 lb-in often serves as a "Thermal Capacity Rating". This metric is critical because it defines the limit at which a machine can operate continuously without overheating. While a gear reducer might be capable of a higher mechanical output (such as 2,419 lb-in), the 1,558 lb-in threshold ensures the longevity of the components by balancing work output with heat dissipation. Precision in Heavy Machinery

Based on the safety requirements outlined in related FAA directives like AD 92-08-04

This is the maximum torque the internal components (gears, shafts, bearings) can physically withstand without breaking. For a standard 3.25" box size reducer, this might be as high as 2,419 in-lb Thermal Capacity (1,558 in-lb):

Let us examine the three most probable interpretations of "1558" in a torque context.

Inspect the rudder torque tube fitting to determine if it is made of