Advantages of double helical gear :
- They develop opposite thrust reactions thus cancel out the thrust force within the gear itself.
- The net axial force that acts on the bearings is zero.
- Power transmitting capacity is very high.
- By using this high pitch line velocities can be attained.
Disadvantages of double helical gear :
- A double helical gear is expensive as compared to helical gear.
- Balancing of thrust forces depends upon the equal distribution of load between the right and left parts of the gear. Therefore, a high degree of precision is required to locate double-helical gears axially on the shaft.
- No external forces are present.