In a Spin

Date: 16.10.19
Efficiency is key for aerospace applications. That's why we endeavor to make the seals that are an integral part of these ever better and it is what we have achieved with the HiSpin®; PDR RT and HiSpin®; HS40 rotary seals. - By Donna Guinivan

IN SHORT

  • Seals are required to withstand higher speed aerospace applications, especially rotary wing aircraft.
  • HiSpin® PDR RT deals with extremely high speeds with minimal friction and power loss.
  • HiSpin® HS40 offers highspeed performance, specially designed for ‘more electric aircraft’.
  • Both seals are well tested and validated andimprove aerospace application performance.

HiSpin® PDR RT gets rotary wing aircraft in the right gear

Chris Cox, Senior Product Engineer at the Trelleborg Sealing Solutions manufacturing facility in Bridgwater, England, said: “Our customers wanted us to de sign a seal that would provide an even better performance at very high speeds, specifically for rotary wing aircraft. That meant engineering a seal that outperforms anything comparable.

Ensuring that essential lubrication is maintained and preventing any leakage presented major challenges, but with the ne w HiSpin® PDR RT rotary seal we were able to overcome them.”

Overcoming a paradox

Efficient lubrication on the one hand, and a dry shaft on the other were needed. That might sound like a paradox, especially for a single component, but it is ensured by a unique design of the sealing lip in the HiSpin® PDR RT. Withstanding extremely high speeds at high temperatures with minimum friction and minimum power loss, it maintains lubrication within the gearbox while keeping the shaft dry.  


The superior high-speed sealing capability of the HiSpin® PDR RT, not only matches the needs for high speed rotary seals in helicopter gearboxes but also provides a longer lifetime for the gearbox assembly, resulting in a better service life for the helicopter and ultimately it increased safety.

Higher rotational speeds

Running in dry, moist or lubricated environments, HiSpin® PDR RT meets an ever growing demand for seal integrity at increasingly higher rotational speeds. Its excellent sealing characteristics allow continuous use at speeds of up to 60 meters per second.


The combination of a unique material, an innovative manufacturing process and specialized sealing lip design, reduces friction by up to 75 percent when compared to traditional PTFE seals. This leads to a significant reduction in power consumption, heat generation and wear on both  the seal itself and its mating surface.

Outstanding test results

The design of the HiSpin® PDR RT has been optimized so it can run on a range of surface finishes and coatings, including ceramics. In in-house tests, the seal has undergone more than 20,000 hours of endurance testing, with this pioneering design operating at 3,500 hours leak free.

FEATURES AND BENEFITS - HiSpin® PDR RT
  • Capable of operational surface speeds up to 60 m/s (195 ft/s) and beyond
  • Bi-directional sealing capability
  • Compact design reduces assembly space requirement
  • Wide temperature range, from -60 °C to +200 °C (-75°F to +390°F)
  • Ability to handle pressure
  • Excellent sealing performance with and without lubrication
  • Extremely low friction and heat development
  • Wide media compatibility
  • Negligible shaft wear
  • Design optimized for durability and long service life
FEATURES AND BENEFITS - HiSpin® HS40
  • Works at high speeds up to 40 m/s (130 ft/s)
  • Bi-directional sealing capability
  • Compact design to reduce assembly space
  • Wide temperature range, from -45 °C to +200 °C (-50°F to +390°F)
  • Ability to handle run out
  • Excellent sealing performance in different lubricated environments
  • Exceptional low frictional torque
  • Reduction of heat development
  • Proven compatibility with various eMobility transmission and other aggressive fluids
  • Negligible shaft wear
  • Easy installation
  • Cost effective
  • Available in different outer diameter configurations, e.g. partially rubber covered
Making electric cars possible

Not just for aerospace applications, HiSpin® PDR RT and HiSpin® HS40 will contribute to extending the travelling distance of electric cars.


Jan Zumbach, the head of business development for eMobility at Trelleborg Sealing Solutions, says that overcoming ‘range anxiety’ is critical to mass adoption of electric vehicles. “With gasoline or diesel vehicles people know they will get where they need to. The infrastructure is there and filling up the tank is never an issue.

“When people drive an electric vehicle they worry if they will have enough charge to arrive at their chosen destination. The solution to this is to install a charging infrastructure and increase battery capacity to extend the distance that can be travelled on one charge.”


As electric motors run most efficiently at high speeds, seals within the e-axle need to operate at speeds beyond the capabilities of standard seals. HiSpin® PDR RT and HiSpin® HS40 increase operating rotational speed to at least 40 meters per second, which will help increase battery capacity.

Electric in the Skies

The development of “more electric aircraft” holds huge potential and at the same time many challenges for aerospace systems and their sealing solutions. To meet these new demands, HiSpin® HS40 represents a ground breaking design for eMobility applications. Tested under extreme conditions, HiSpin® HS40 offers superior cost-effective performance and reliability. Its outstanding low friction capabilities meet the demanding conditions of high-speed electric aerospace applications, such as electric hoists and electro mechanical actuators.

Innovative design and materials

A unique hydrodynamic feature within the HiSpin® HS40 helps reduce frictional torque. Simultaneously, oil back pumping leads to improved sealing performance without causing any damage to the shaft.


The seal is manufactured with our proprietary XLT high-performance fluoroelastomer (FKM). This material provides outstanding resistance to extreme engine conditions resulting from high motor speeds and aggressive synthetic fluids. Testing of the new generation of XLT compounds has proven that these low temperature FKM grades outperform and extend the temperature performance capability of traditional FKM materials.