H4-DV21-B gear units W Gear units with auxiliary drive Qua Helical gear boxes H4

Flender/Flender Gear Units/Helical gear boxes H4

ing which the gear was subject to signicant uctuating operating conditions. The pinion completed 1 whole rotations, while the gear only completed 6. single averaged datum point corresponds to each gear mesh period. This renders it possible to synchronous average the NLL values with respect to both the pinion and the gear without the need to resample the NLL signal. large average NLL value corresponds to the 1th pinion tooth, clearly indicating the presence of the fault induced signal irregularity. In this simple analytical example, the NLL synchronous average was able to clearly detect tooth damage, which could not be detected by conventional synchronous averaging. 4. Experimental setup The proposed NLL synchronous averaging methodology is subsequently investigated on experimental data which were recorded in the Sasol Laboratory for Structural Mechanics at the University of Pretoria [1]. 5.5 kW Induction motor Flender 6 gearboxFlender 2 gearboxAlternator 5.5 kVAFigure 7: The experimental setup of the gear test rig. Gear damage was investigated on single stage Flender E2A gearbox (rated load of 2 Nm) with helical gears and step up ratio of 1:1.9. mounted test bed was designed to conduct accelerated gear life tests on the gearbox under time-varying load conditions. As such the monitored gearbox was mounted between two Flender E6A gearboxes, the rst of which served to step the torque up and the second to step it down. The E6A gearbox pair increased the torque over the E2A test gearbox by ratio of 1:4.7. The fundamental system frequencies are presented in table 4. Table 4: Fundamental frequencies Gearbox Role Shaft input Teeth ratio Shaft output Mean Meshing Frequency Flender E6A Speed step down 2.5 Hz 1/8 5.1 Hz 4Hz Flender E2A Test gearbox, speed step up 5.1 Hz 4/2 1.1 Hz 2Hz Flender E6A Speed step up 1.1 Hz 8/1 4.8 Hz 8Hz The step down gearbox was driven by 5.5 kW three phase four pole WEG squirrel cage electric motor. The step up gearbox was connected to