WELCOME TO
RANDOLPH RESEARCH CO.
LAMIFLEX® Hi-Load Rubber Laminate Bearings / Seals

What are rubber laminate bearings?
They are made of many thin alternate layers or laminations of metal and rubber (elastomer) bonded together to form a stack. The laminations may be flat (as shown in the sketch), conical, hemispherical or curved to form a cylinder. Lateral motions between successive metal layers are permitted by shearing action within and parallel to the intervening rubber layers. At the same time, this stack of laminations can sustain high normal forces (e.g., 10,000 psi or more), with very slight compression because of negligible extrusion of the rubber out from between the metal laminations due to the thinness of the layers (as thin as .002" for some small bearings, but shown thicker for clarity).

So the laminate bearing can resist thrust, radial, or combined normal forces (depending upon its configuration) when they are imposed upon its outer layers, while permitting limited lateral or angular movement between those opposed outer members. This motion may include oscillatory pivoting about a normal axis, or transverse shifting, and results in a distribution of the shearing movement between the individual rubber layers, as indicated in the sketch by the change from a vertical line drawn on the edge to a slanted staircase in either direction. There is a proportional opposing force or torque resulting from the rubber shear stress, with negligible frictional resistance against this movement. Usually, the two outermost metal laminations are made thicker to form external load faces and permit keying. Obviously, continuous rotation is not possible.

Following Randolph Research's original patent for rubber laminate bearings, they have become the usual standard for retention of rotor blades in helicopters, sustaining many tons of centrifugal force while permitting pitching oscillation of each blade once per revolution of the rotor, greatly increasing lifetime over ball or roller bearings, with no lubrication. Wind turbine blades are a new possibility.

Recently developed LAMIFLEX Bearing-Seals are rubber laminated bearings with a central aperture that provide a hermetic seal against the radial flow of liquids or gasses between their periphery and their aperture, even under large differential pressure. These provide new opportunities for design of undersea craft (or other pressure vessels). They support and seal shafts that safely penetrate the hull. Test bearings were oscillated at +/- 15 degrees under 10,000 psi pressure for over 1 million cycles.

Some Applications
Helicopter and wind-turbine blade retention bearings for feathering axis motion while absorbing tons of centrifugal force.

For undersea craft (or other pressure vessels), bearing-seals to support and seal shafts that penetrate the hull. A flat washer type was oscillated at +/- 15 deg. under 10,000 psi differential pressure for over 1 million cycles.

Recent Paper
LAMINATED-RUBBER BEARINGS: FROM HELICOPTERS TO THE DEEP SEA - NEW POTENTIALS FOR UNDERSEA CONTROLS, Presented at UUST11, Portsmouth, NH, Aug.21-24, 2011 (expanded transcript)

Who are we?
We invented the concept of high-load rubber laminate bearings and developed the first application, helicopter blade retention (now standard practice). High-pressure LAMIFLEX laminate bearing-seals are a more recent innovation.

We're a small company dedicated to developing and making LAMIFLEX bearings and seals for various custom applications.
More information? Contact us
E-mail: info@randolphresearch.com 
Phone: Bill Hinks at 330-760-0744.

Randolph Research Co.
PO Box 336
Bath, Ohio 44210-0336

Updated 10/20/2011