**3.1 Test-rig**

The test-rig employed for this investigation consists of one identical oil-bath lubricated gearbox, 3 HP-motor, rigid coupling, tapper-roller bearing, pinion, gear, control panel and break system, as seen Fig. 4. The pinion was made from steel with heat treatment, the number of teeth is 70, and diameter is 140 mm. The gear was made from steel, but it was produced without any heat treatment process during manufacturing. The number of gear teeth is 50 and diameter is 100 mm, and module is 2 mm for the gear and pinion, respectively.

Fig. 4. Test-rig

(a) Envelope analysis

Fig. 3. The comparison of Power spectrums in Envelope analysis with/without DWT

The test-rig employed for this investigation consists of one identical oil-bath lubricated gearbox, 3 HP-motor, rigid coupling, tapper-roller bearing, pinion, gear, control panel and break system, as seen Fig. 4. The pinion was made from steel with heat treatment, the number of teeth is 70, and diameter is 140 mm. The gear was made from steel, but it was produced without any heat treatment process during manufacturing. The number of gear teeth is 50 and diameter is 100 mm, and module is 2 mm for the gear and pinion,

(b) Envelope analysis with DWT

**3. Gearbox 3.1 Test-rig** 

respectively.

Fig. 4. Test-rig

A simple mechanism that permitted a break of disk-pad type to be rotated relative to each other was employed to apply torque to the gear. Contact ratio (Pinion/Gear) of the gears was 1.4. The motor used to drive the gearbox was a 3-phase induction motor with a maximum running speed of 1800 rpm respectively and was operated for 15 days with 1500rpm. The torque on the output shaft was 1.2 kN·m while the motor was in operation, and other specifications of the gearbox are given as in Table 1.


Table 1. Specification of gearbox and bearing
