Hello. I need to calculate spur gear transmissions. I need a bit of guidance for the first steps. The data is the next: n= 1000 rev/min Mt torque= 28.65 Nm i transmission ratio= 4 P load in the shaft= 3kW I am a bit lost to star selecting the material (depending the load and work conditions). The strees of the transmissions and the module of the gears. I understand that I need to check the material in a catalogue of materials. But honestly I am lost trying to select the right one and fail at the beginning of my calculation of gears. Later on when I have to calculate the module, which date should I set as I random number, the number of teeth then I will be able to calculate the module later. Thank you.