CONSTRUCTION AND MATERIALS
Gears
23. The spur gears of the external or auxiliary gearbox gear train (fig. 7-4 and 7-5) are mounted
between bearings supported by the front and rear casings which are bolted together. They transmit the
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| Fig. 7-4 An external gearbox and accessory units. |
units and approximately 20,000 r.p.m. for the centrifugal breather.
24. All gear meshes are designed with 'hunting tooth' ratios which ensure that each tooth of a gear
does not engage between the same set of opposing teeth on each revolution. This spreads any wear
evenly across all teeth.
