Types of final drives

1.Bevel drive:
 

•  Bevel drive consists of a bevel pinion and crown wheel

     

  There are three types of bevel gears namely

  (a) Spur  bevel gears

   

   (b) Spiral bevel gears

             

  (c) Hypoid gears

  

  Gear ratio =Number of teeth on crown wheel/Number of teeth on pinion

 a) Spur  bevel gears:

•   Have straight teeth

•   Only one pair of teeth of pinion and the crown  wheel will be in contact

•   Uneven transfer of load from one pair of teeth to  the next

•   These gears are noisy and prone to faster wear

b) Spiral bevel gear:

•   These gears have curved teeth profile

•   The load is transferred smoothly and quietly

•   These are stronger than straight bevel gear

c) Hypoid gears:

•   These gears are arranged to have the axis of pinion   below that of ring gear

•   This permits a lower position of propeller shaft