A rubber bearing is defined as a tool which allows constrained relative motion between two parts—rotation or linear movement. the elemental purpose of an impact is to scale back friction and wear between rotating parts which are available contact with each other in any quite mechanism. Bearings are classified broadly into categories consistent with the motions they permit and consistent with their principle of operation. Each sort of bearing is employed for various purposes. Bearings are made from various materials but rubber may be a widely demanded material for creating bearings. Rubber has proved to be a superb bearing material, especially under circumstances during which abrasives could also be present within the lubricant. The rubber wont to make bearings may be a tough resilient compound similar in texture thereto in a car tire. aside from this main application, bearing devices must also allow –or prevent- relative movements (rotation and movement) of the joining elements and have durability consistent with the lifetime of the structure they're placed in.
Among all different kinds of bearing, elastomeric bearings – in their different types- are the best known and most often used.
Types of rubber used in making bearings
• Natural Rubber
• Butyl Rubber (IIR)
• Butadiene Rubber (BR)
• Ethylene Propylene Diene Monomer (EPM, EPDM)
Types of Rubber Bearings
• Plain and Laminated elastomeric bearings: Bearings for the housing industry in neoprene and natural rubber compound. Laminated rubber bearings provide the only method of isolation and are best suited for top frequency ground motions.
• High Damping Rubber Bearing (HDRB): this is often ideal for seismic isolation. they're vertically stiff, capable of supporting vertical gravity loads while being laterally flexible, capable of allowing large horizontal displacements. In effect, during an earthquake, the bottom is allowed to manoeuvre back and forth under a base-isolated, while leaving the building to stay "stationary." These HDRB bearings are flexible and have energy absorption capability. The rubber bearings isolation system partly reflects and partly absorbs a number of the earthquake input energy. Significant reductions of structural and non-structural damage also can be attained through the utilization of HDRB rubber bearings seismic isolation.
• Low Damping rubber bearing: within the isolation system, the various sorts of rubber bearings are designed and used alongside dampers. The system that's popularly adopted for buildings is that the elastomeric or rubber bearings with low damping. These rubber bearings are widely accepted due to their longevity, economy and better control on dynamic properties.
• Lead Rubber Bearings (LRB): A lead rubber bearing may be a much larger laminated bearing manufactured from layers of rubber which are sandwiched alongside layers of steel and within the middle of the bearing there'll be a solid lead "plug." Top and bottom of the LRB is fitted with steel plates, which are wont to attach bearing to putting together through its foundation. Lead rubber bearings are designed during a way that the bearing is stiff and powerful in the vertical direction and versatile in the horizontal direction. Lead, inserted as the centre of LRB dissipates the energy of earthquake and therefore the rubber, reinforced with steel plates helps in providing stability, supports the structure and isolates vibrations.
• Highly resistant