58-62 HRC Customized Spiral Bevel Gears in Helicopter Transmission Systems

1) Features of Spiral Bevel Gear

• Unlike the straight tooth profile of spur bevel gears, the tooth line of helical bevel gears is curved and helical in shape. This enables the meshing process to commence at one end of the tooth and transition smoothly to the other, rather than achieving simultaneous full-line contact.
• Owing to the presence of the helix angle, multiple tooth surfaces remain in meshing contact simultaneously, achieving an exceptionally high overlap ratio. This fundamental geometric characteristic underpins their capacity for smooth, robust power transmission.

2) Functions of Spiral Bevel Gear

• Its core function lies in efficiently and smoothly altering the direction of power transmission. The helical tooth design significantly improves the ‘handover’ process between teeth, minimising impact and noise.
• Through the complex principle of partial conjugate meshing, it actively controls the shape and position of the contact area between tooth surfaces while transmitting power. This is key to optimising its performance and service life.

3) Application of Spiral Bevel Gear

Widely employed in the main reduction gear of automotive rear axle differentials, its smooth operation directly impacts driving comfort and noise levels. It is also utilised in helicopter main rotor transmission systems, where demands for dynamic balance and resistance to impact loads are exceptionally stringent.