580470.fig.004a
(a) Nitrided driving gears
580470.fig.004b
(b) Nitrided driven gears
580470.fig.004c
(c) Nitrided+TiN coated driving gears
580470.fig.004d
(d) Nitrided+TiN coated driven gears
Figure 4: The photograph of tooth surface after running test magnified 50 times.