A new large construction vehicle design required an array of aluminum bronze bushing sizes. CCTY Bearing reviewed the application, its loads and the mating components of the requested bushings. Concern was raised that the design lengths of the bushings were too long relative to the application loads on the shafts. The kind of loads that might create excessive shaft deflection within the bushings length.
CCTY Bearing requested a FEA – finite element analysis – of the shafts focusing on the amount of shaft deflection within the given length of the bushing. Excessive shaft deflection will deform the edges of the aluminum bronze bushing reducing its ability to perform as needed over time.
The FEA results confirmed CCTY’s concern, so the length of the bushings were reduced preventing deformation due to shaft deflection.
After receiving an inquiry about the bushings and learning more about the application, CCTY Bearing’s engineers questioned the generous design length of the bushing.
Initially, the bushing length appeared to be necessary for heavy application loads on the dozer’s shafts. The belief was that a longer bushing would provide a bigger load zone and reduce the PSI on the bushings surface.
An FEA confirmed the concern of CCTY’s engineers. It proved the additional length would not provide the load support as originally specified. The challenge was finding a way to accommodate the same loads with a bushing shorter than the original design length.
Having an in-depth background in bushings and finishes, CCTY Bearing’s engineers suggested that the right press fit with a closer bushing inner diameter to the outer diameter of the shaft would lead to an increased load zone, which would reduce the PSI on the bushing.
Press fits, manufacturing tolerances, tolerance stack-ups, concentricity’s, surface finishes, lubrication methods, chamfers and materials were evaluated. The necessary adjustments were made, increasing the load capacity of the shorter bushing enough to satisfy the application.
Competing bushing designs were evaluated by the engineering group for the dozer, including composite bushings. CCTY Bearing’s design was chosen because it proved to be the best solution to handle the application loads without galling the shaft’s surface.
“Sample requests allow us to work directly with the OEM and share our bushing expertise. In this situation, our team found a solution before it became an issue in the final product. This example showcases how CCTY Bearing works directly with customers to improve their design.”
John Sweetwood, Strategic Sales Manager
Backed by results from the FEA and field tests, the OEM’s team implemented the shorter aluminum bronze bushing with CCTY Bearing’s recommendations. The correctly engineered bushing fully protects the expensive shaft and handles the rigorous application loads generated from earth moving equipment.
CCTY Bearing’s solution proved to be:
- An enhanced design that eliminated premature bushing failure
- Greater protection for an expensive component
- Reduced cost with the shorter length bushing
The client is now able to manufacturer the machine with a part that is the right fit for the application.