Spiral Bevel Gears for Construction Drive Axles

Client Background#

The customer is a manufacturer of construction machinery and drive vehicles. The drive axle it builds calls for a high-performance spiral bevel gear pair with a high torque capacity, and the customer buys the two members as a matched set rather than as separate parts. The application is a drive axle in construction machinery, so durability under high torque is the working requirement and the gear pair has to hold its geometry over a long service period.

Requirement & Challenge#

• Module M8, helix angle 35°, material 20CrMnTi
• Paired lapping, with a tooth contact pattern of 60% or more
• DIN 6 batch accuracy

For a bevel gear pair the contact pattern is the working criterion. Unless the two members are lapped against each other, the load concentrates on part of the flank instead of being spread over the tooth surface, and the pair then runs hot and wears quickly even when every single dimension is within tolerance.

Solution & Process#

1. Gear milling + gear grinding - The teeth are milled to the Gleason system and then precision ground, so that the geometry produced by milling can be corrected to the accuracy required for the axle.
2. Paired lapping - Every gear pair undergoes matched lapping, so the two members run in against each other before they leave the factory, and the contact pattern is established on the pair that will actually run together.
3. Full dimensional inspection - Tooth pitch, tooth profile and helix are inspected on each gear, and the pair is released only when the contact pattern criterion of 60% or more is met.

Result & Feedback#

• Contact pattern reached 65%, with smooth transmission
• Load capacity increased 25%
• Mass delivery of 2000+ pieces, zero returns