Developed the concept of high-load rubber laminate bearings and the first application for helicopter blade retention in place of ball or roller bearings. LAMIFLEX Bearing-Seals for underwater hermetic shaft seals are a more recent innovation.

1. Laminated Rubber Bearings
Heavy Duty Composites for
Aerospace and
Undersea

2. Laminated Rubber Bearings
(Elastomeric Bearings)
• Composite of elastomer and metal layers
• Support massive structures
-Permit thermal expansion
-Isolate bulidings from earthquakes
-Big, maybe 1/2 inch thin
• Small & dynamic
-Helicopters
-Undersea

5. (Seen from above,
moving up on picture)

6. Heavy Duty for a Thrust Bearing
• Tons of CF while oscillating
+/- a few degrees
• Early failure of ball / roller bearings
-spalling, fretting corrosion
A New Idea was needed ---
Laminated Rubber Bearings

7. (Seen from above,
moving up on picture)

8. Laminated Rubber /
Elastomeric Bearings
•Easily handle tons of CF
•Oscillate at high frequency
•No lubrication
•NR for high resilience
Used on most helicopters now

9. Enstrom – First with Elastomeric Bearings

10. Enstrom Bearing Design
• 2-1/4" in diameter
• More than100 rubber
& brass layers each
• All layers 0.002” thick
• 18,000 lbs. CF

11. Small Wind Turbines
• Blade pitch angle
variable with wind
• Increase efficiency

12. Compression Very Slight
• At 10,000 psi pressure on bearing
- thinner by a few sheets of paper
- about .010 of an inch
• Rubber layers can’t squeeze out
- because rubber layers are very thin
-only .002 of an inch thick
• Compression due to volume decrease

13. One-inch Square Laminate
Pads
• 40 layers
.002’ brass
• 39 layers
.002” NR
• Bendable
• RIGID

16. • RRC specializes in laminates with
very thin layers
• Small helicopters
• Chemical bond of NR to hi-tensile
brass
• Lack of adhesive reduces thickness
• Larger helicopters use thicker,
fewer layers

18. Planar & Chevron
• Planar
- angular oscillation & lateral movement
- easier to make – no metal forming
• Chevron
- precludes lateral shifting
- permits taller bearing for given load

19. Conical
• Combined radial & thrust
loads
• Angular motion about axis

20. Cylindrical (Radial) Bearing
• Circular & axial motion
• Wrapped around shaft
• Axial thermal expansion
of shaft
• Silicone rubber for heat

21. Spherical Bearings
• 3D angular motion about center
- rotation about longitudinal axis
- tilting L/R and in/out of screen

22. Helicopter Spherical Bearing
• Many large helicopters
• Ordinary pitch oscillation
• Also lead-lag & flapping

23. Design Factors
• Diametral dimensions
• Height
• Load forces
• Torsional stiffness
• Oscillatory torsional shear strain
• Fatigue life
• Angular range.

24. Some Relationships
• Torsional Stiffness
- prop. to 4th power of diameter
- inverse with height
• Torsional Shear Strain for given angle
- prop. to diameter
- inverse with height
• Fatigue Life
- Max oscillatory torsional shear strain
- internal pressure
- other factors

25. Bearing-Seals
• A more recent development by RRC
• New design opportunities
for undersea craft

26. Undersea Bearing-Seal
It’s the same thing!
-An ordinary laminated rubber bearing
- Top and bottom enclosed
•Circular body makes a hermetic seal
- Seawater outside can't penetrate
- Solid barrier around central hole

27. Undersea Bearing-Seal
It’s the same thing!
• Seals against immense pressure
-tested to 17,000 psi
• No flimsy sliding surfaces like lip or face
• Immune to sand and grit
• Torque remains constant with depth

28. What can we do with a
bearing-seal?
• Suppose we have a pressure vessel
- like a submarine
• And suppose we want to have a sealed
shaft that extends from the inside of it to
the outside
- like a diving plane shaft
• We can do that with a bearing-seal.

29. AUV
• Small autonomous robotic submarine
• Looks like a torpedo, but leisurely
• Loaded with sensors
- pressure, temps, sonar, guidance
• Pre-programmed for a mission over area
• Military, Scientific, Offshore Oil & Gas
- mine-hunting for the Navy
- sensing ocean variables
- inspect underwater oil & gas pipelines.

31. Application of Bearing-Seals
• Mount & seal external hydrofoils that can
control AUV:
- direction by rudder
- climb/descent by diving planes
• Even “fishtail” propulsion
- swivelling tail fin back & forth
• Advantage of actuation in air environment
- low cost, off shelf actuators
- no worries about seawater corrosion

33. Typical Bearing-Seal
• OD = 2.06", ID = 1", ht. = 1/2“
• 80 hi-tensile brass + 78 natural
rubber layers, both .002" thick
• 10,000 psi water pressure
outside
• +/- 15 degrees for 1,000,000
cycles
• Also cycled at max sea depth,
17,000 psi

34. Bearing-Seal application similar to
helicopter use
• Bearing - as well as hermetic seal
• Angular movement/oscillation
+/-15 degrees
• High force -intense hydrostatic pressure
instead of centrifugal force
• Millions of cycles

35. Laminated Rubber Bearing
Technology
• Simplicity
• Low cost
• No lubrication
• Reliability
• Long life
For vehicles that
Probe the sky and depths of the sea