Sealing System for Landing Gear
Sealing systems used in the aircraft landing gear shock absorbers investigated here are normally expected to last 10 years without the need for maintenance. To achieve this it is therefore important to have a reliable sealing system with low friction that also minimises leakage. The aerospace industry is moving away from the use of hard chrome in sliding cylinders and alternative surfaces have been considered using thin coatings. The project involved an experimental study of the long term variation in friction of new compared with current coatings, and the development of new FEA based methods for predicting friction and wear.
The work was performed for Liebherr.
Project Goals
- Experimentally replicate the environment and so long-term performance of a nose landing gear system
- Determine the tribological characteristics of nano-coatings on metallic counter-faces
- Conduct experiments under transient short stroke conditions at representative pressure (30bar fluid pressure) and operating temperatures (-40 to + 40 oC)
- Evaluate variation in friction with duty cycles, impact of surface roughness, and variation of the friction profile with stroke
- Measure seal friction rods under conditions of short stroke reciprocating motion
- Compare performance of chrome and HVOF coated WCCoCr and NiCr-BSi surfaces
- Compare the friction properties of a commercially available elastomer seal arrangement
Applications
- Develop a cost-effective accelerated testing technique
- Rapid evaluation of new environmentally friendly coatings
- Select appropriate seal system designs, seal and housing
- Design tool to predict contact behaviour of the sealing systems when subjected to various pressure conditions, and friction and wear behaviour under lubricated condition
- Predicting the life of seals based on changes in the physical condition