Planet Gear Shaft

The planet gear shaft is a critical component in automatic and hybrid transmissions, supporting the planet gears as they rotate and orbit. We manufacture it from ultra-high-strength alloy steel, with a deep case-hardening process that produces a hard, wear-resistant surface layer of HRC 60–64, while the core remains strong and flexible. This provides excellent resistance to bending and shearing, with highly stable dimensions that maintain gear clearance under high torque and high speeds. The result is smooth transmission operation and efficient power flow.

This shaft is used in the planetary gear sets of multi-speed gearboxes, acting as the central support for the planet gears. Its performance determines the load capacity of the gear set and directly affects noise, vibration, and harshness levels. It withstands complex and fluctuating stresses during frequent gear shifts and full acceleration. Our planet gear shaft is engineered for these demanding conditions, ensuring precise power split and combination.

We use high-grade case-hardening bearing steels such as 20CrMnTiH or SAE 8620. Forging produces a dense, uniform microstructure, while heat treatment in a controlled-atmosphere furnace ensures an even, smooth hardened layer. Production follows the IATF 16949 quality management system and strict cleanliness standards such as ISO 16232, preventing contamination by particles that could affect the transmission valve body.

Critical dimensions-including shaft diameter, length, shoulder positions, and oil holes-are precisely matched to the planet gear and carrier. CNC precision grinding and super-finishing deliver excellent roundness, straightness, and surface smoothness. We work closely with customers to support custom designs for different transmission types, including Lepelletier or Ravigneaux systems. Customization options include light-weighting, strengthening, and optimized oil flow.

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