A test unit for quantitative analysis of a contact pattern and a method for quantitative analysis are provided. The test unit comprises an optoelectronic sensor that captures images of a contact pattern paint on a tooth surface of a gear. Furthermore, the test unit comprises a control unit, which is configured to determine and store a first distribution of an optical parameter of the contact pattern paint across the tooth surface from the first image. This is captured prior to testing of the gear. After the tooth surface is exposed to a test load, a second image is captured and a second distribution of the optical parameter is determined. The control unit is configured to perform a quantitative analysis of a contact pattern on the tooth surface by determining a deviation between the first and the second distribution of the optical parameter.

A power transmission system having at least one inlet speed-reducing gear and a main speed-reducing gear, each inlet speed-reducing gear comprising an inlet pinion meshing with an inlet gearwheel. The inlet gearwheel is constrained to rotate with a main pinion of the main speed-reducing gear, the main pinion meshing with a main gearwheel. At least one inlet gearwheel is secured to reversible connection means in order to be capable of driving a first additional drivetrain connected to an additional rotor.

In order to decrease computation requirements for updating ease-off for simulated mating gears upon changed misalignment and calculating corresponding gear penetration, the effect of gear misalignment is linearized. At least one representation of misalignment is added to an initially calculated ease-off to update the ease-off in response to the misalignment. The at least one representation of misalignment includes a representation of relative translation misalignment between the gears, a representation of relative rotational misalignment between the gears, a relative approach between gear flanks at a contact point, or a combination thereof.

A method of modifying a workpiece includes providing a workpiece, determining a load stress profile associated with a load condition, the load stress profile comprising a load stress greater than a material stress limit of the workpiece, determining a residual stress profile, the residual stress profile comprising a residual stress less than the material stress limit of the workpiece, and providing the workpiece with the residual stress profile, wherein a sum of the load stress and the residual stress is less than the material stress limit of the workpiece.