Timken's integrated flexpin bearing features pins pressed into only one wall of the gearset carrier. At the free end of the pin, an annular sleeve and bearing assembly support the gear. Under load, opposing bending forces in the sleeve and pin offset one another, resulting in zero misalignment across a broad range of torque. This enables much simpler gear design while providing significant torque reduction.

When compared with an equivalent sized, conventional planetary gear system, the highly engineered integrated flexpin, or flex drive, bearing can provide greater power. It is the right solution for the most challenging applications: aerospace gearboxes, construction equipment final drives and wind turbine gearboxes. This solution creates new and very substantial opportunities for machine designers to either downsize systems or to upgrade the rated horsepower of their existing machinery, and to achieve higher levels of performance.

Design Attributes

• Offsetting torsion in the pins and annular shafts supporting the gears results in equalized loads.
• Gear misalignment created by induced carrier deflection under load is reduced or eliminated. Load distribution among planets within an array are equalized.
• Design reduces gear loads and the need for gear profile and lead correction. Enables smaller, lighter gears for weight-sensitive applications.
• Provides greater torque capacity within the same space.

Applications

• Gear drives in aerospace, agricultural, defense, heavy industry and mining applications.

High performance epicyclical gearing systems inherently place more stress on all the components. Gear stresses are elevated from load and misalignments created by the torsional wind up of the planetary carrier. Designers may try to solve this stress problem by increasing face length and using lead correction and gear profiling to manage the stress along the gear tooth. While it may be logical to decrease unit load by increasing the number of planets to more than three, it becomes less certain what percentage of the power is being transmitted through each mesh. All of these challenges can be resolved by applying one simple product.

Timken's integrated flexpin bearing is built around the principle of a double-cantilever shaft that extends from a single walled planetary carrier. This construction provides circumferential compliancy among planets to ensure uniform load distribution among the planets (testing shows K-gamma for 7 planets is close to unity at all load levels). Just as important, the single walled carrier construction virtually eliminates gear tilting from torsional wind up. This means unit loading on the gears and bearings is decreased by virtue of using more planets and improving K-gamma, and misalignment from torsional wind up is virtually eliminated.

Additionally, the integrated flexpin construction is based on full integration of bearing races with the planet gear and sleeve, allowing radial space for the bearing rolling elements. Bearings may also be very precisely preloaded at the bearing factory so that the spring rate of each IFB remains constant permitting uniform loading among planets. The integrated flex pin represents state-of-the-art technology in epicyclical gearing system design. Its compliant construction offers the greatest opportunity for reducing gear mass and balancing reliability of all system components.