Solving Transmission Housing Leakage in Agricultural Equipment

Overview

A client supplying hydraulic transmission assemblies for agricultural machinery faced significant challenges due to environmental exposure. The equipment operates in extreme temperatures ranging from -15°F to 250°F, with fluid pressures peaking at 50 psi. These assemblies, often stored outdoors, are subjected to various natural elements, including rain and freezing conditions.

Challenges

The end user reported leakage at the bottom cover gasket interface of the hydraulic assemblies. The existing sealing solution, which involved a solid nitrile gasket compressed between the transmission housing and the bottom cover plate, presented several issues:

Over-Compression: The gasket was compressed by torquing 10 self-tapping screws to 100-120 in/lb, leading to over-compression without the aid of a compression limiter, resulting in a loss of shape.
Uneven Sealing Pressure: The solid nitrile gasket failed to distribute sealing pressure evenly across the interface.
Installation Issues: Misalignment between the gasket and the transmission housing caused fraying of the rubber during installation.

Integral Seal™

Parker’s Solution

Parker developed a customized rubber-to-metal bonded Integral Seal™ gasket, incorporating the following key features:

Rigid Aluminum Retainer: The retainer matches the thermal expansion properties of the mating hardware, providing stability and preventing over-compression.
Edge-Bonded FKM Sealing Element: The vulcanized fluorocarbon (FKM) sealing element is edge-bonded to the aluminum retainer, ensuring consistent performance under varying temperatures.
Compression Limiter: The rigid frame serves as a compression limiter, maintaining the sealing element’s elasticity and force by preventing over-compression.
Consistent Bolt Hole Alignment: Utilizing a precise metal stamping process, Parker ensures bolt hole locations within .008”, eliminating misalignment during installation.

Conclusion

A Fuji impression of the newly engineered design confirmed an even distribution of sealing contact pressure against the mating hardware, significantly improving upon the previous solution. This innovative approach resolved the leakage issues, enhancing the reliability and durability of the hydraulic transmission assemblies in harsh agricultural environments.

This case study highlights Parker’s commitment to engineering tailored solutions that address specific customer challenges, ensuring optimal performance and longevity of their products.