To test seals for critical applications, Trelleborg Sealing Solutions invested in one of the world’s most powerful test benches for hydraulic rod seals. This facility allows testing to be carried out that has never been possible and has been used to qualify the seals for the landing gear of the Airbus A350. The sealing system has successfully passed 20,000 full landing cycles, plus additional tests for ice scraping and water spray.
Installed in a specially constructed concrete well to isolate vibrations from surrounding buildings, the 18-ton, 260-kW floating-mount rod seal test bench is located at Trelleborg’s research and development center in Stuttgart, Germany. It is capable of simulating the patterns of movements and stresses faced by hydraulic rod seals in some of the most demanding rod seal applications. The drive unit was set up in a separate room so that energy otherwise lost through emissions can be used in an environmentally-friendly manner to reheat the building.
“The rig can perform long-term endurance and development tests, reproducing the effect on hydraulic rod seals,” said Eric Seeling, the engineer responsible for the design of the test bench. “In particular, it excels in aerospace applications where it can check parameters such as braking or lateral forces on landing gear and even simulate life-like knocking caused by uneven runways; what might be called a bumpy landing.”
The test bench is suitable for seals from 100 to 400 mm (4 to 16 in.) in diameter and can test a complete sealing configuration in a single test construction, replicating the pressure between the primary and secondary seals realistically. Travelling at speeds of up to 1 m/sec or 3.3 ft/sec or frequencies up to 10 Hz, it can generate movements and pressure patterns in sine waves, trapezoidal forms and even freely modelled patterns.
One of the test bench’s more novel features is a lateral force cylinder mounted at the bottom of the bench. Capable of exerting forces of up to 225 kN, it can place permanent radial loads on the seals, or, depending on the stroke, exert dynamic loads. ￼