Components, systems and materials › Bridge components › Pot bearing
Pot bearing
What it is
A pot bearing confines a rubber disc inside a steel pot under a close-fitting piston, carrying high vertical loads while allowing rotation; with a sliding plate it also allows horizontal movement.
Where it is used
Long-span and heavily loaded bridges, viaducts, metro and railway structures, and large industrial structures.
How it works
Rubber confined on all sides behaves like a very viscous fluid. It cannot squeeze out, so it carries very high pressure, yet it allows the piston to tilt, giving rotation capacity. A PTFE sheet sliding on polished stainless steel on top of the piston lets the deck move with low friction; guides restrict movement to one direction where needed.
Types
- Fixed pot bearings (rotation only)
- guided sliding pot bearings (movement in one direction)
- free sliding pot bearings (movement in all horizontal directions)
Materials
Steel pot and piston, natural rubber or chloroprene disc, brass or polymer sealing rings, dimpled PTFE with lubricant, stainless steel sliding plate, anchor bolts or dowels.
The bearing is designed for maximum and minimum vertical loads, horizontal forces from braking, wind, temperature restraint and earthquakes, rotation and movement range. Pressure on the elastomer and on PTFE is limited, and guides are sized for lateral loads. Bearing layout on the pier sets which supports are fixed and which slide.
Installation and QA steps
- Check supplier test certificates and markings for type and direction.
- Set on a levelled and grouted bedding with correct orientation and presetting.
- Fix anchor bolts or dowels.
- Remove transport clamps once the deck is fixed.
- Inspect seals, PTFE wear and corrosion during routine inspections.
- Seal ring failure and extrusion of rubber
- wear or loss of PTFE causing high friction
- transport clamps left in place, locking movement
- corrosion of pot and anchor bolts
Codes cited
- IRC:83 (Parts I to IV) (India): Road bridge bearings: metallic, elastomeric, pot and spherical types by part.
- EN 1337 (series) (Europe): Structural bearings.
Cited by number only. We do not reproduce code text, tables or figures.
Related
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