MAIN & NOSE PISTON SEALS FOR LANDING GEARS

Scenario

In the aeronautical industry, and especially in landing gear applications, the operating conditions are increasingly demanding. Variations in temperature and speed, high number of cycles and pressures undergo all the elements of the shock-absorbing cylinders to considerable stress.

Challenge

Landing gears are a concentrate of technology. Fundamental functions depend on them, such as correct landing. Therefore mechanical design of each component must be extremely precise and studied in depth. One of our customers, leader in the aeronautical industry, asked us to realize new seals using a material characterized by low dilatometric coefficients, excellent resistance to oils, wear and therefore to abrasion.

Solution

Generally seals used in airplanes and helicopters landing gear cylinders retain the oil (generally fluids according to MIL specifications) which is found inside the cylinder itself. These actuators are designed to support high loads and the aircraft itself during landing. Operating conditions include sudden changes in temperature, high pressures and high instantaneous speeds. For this reason, both materials and outlines must guarantee perfect seals and very low friction. ATP studies, tests and produces – within its laboratories in Modena – special PTFE-based materials, capable of responding to the specific needs of applications according to operating conditions.

Application’s technical data

• Max pressure: 550/600 bar
• Temp.: -54°C + 135°C
• Speed: 5/6 m/sec.
• Stroke: 270mm
• Fluid: MIL-PRF oil

After analyzing the application, our technicians identified Sintek 310 with the perfect material to realize a part of the application. Special PTFE loaded with carbon fibers and other additives, Sintek 310 is able to contain thermal expansion and to reduce resistance to the Gap Extrusion phenomenon, moreover it is characterized by excellent resistance to loads, low friction and wear.

The sealing system suggested by our technical office also consists of other Sintek H-TPU-LT+ elements. Sintek H-TPU-LT+is a special polyurethane characterized by high resistance to oils, fats and very low temperatures. Both materials used, upon specific request, can be accompanied by a certificate 3.1.

Testimony

«Thanks to these materials and seals outlines suggested by ATP we can supply extremely reliable products.»