BRIDGE BEARING

1. PTFE: Poly Tetra Fluoro Ethylene
It is a
 Linear chain polymer of high molecular
strength
 Chemically inert
 Low coefficient of friction
 Not oxidized easily
 Remains stable at extreme atmospheric
temperatures
 Resistant to all common solvent.

2. POT END
 POT bearing – It take beneficial properties of
confined elastomer behaving like pressurized fluid in
fixed bearings which helps in rotation and safe load
transfer
 Rotational movement permitted by shear
deformation of an elastomeric pad
 No compressive deflection of elastomer as it is
encased
 Sliding component can be added at top.

3. POT - PTFE END
 Mostly POT at bottom
 PTFE is helpful in design of large expansion
bearings as no rolling action is there
 Uses very low coefficient of friction between
stainless steel and PTFE
 Lateral movement restrained by guides
– Guides can be on either side or in center as per
design

5. POT
ELASTOMER
BRASS
SEAL
PISTON
PTFE
STAINLESS
STEEL
PLATE
WEARING
SURFACES
DUST
SEAL
WIPER
SEAL

6. Side Guides

7. Central guide

9. ROTATION OF POT PTFE BEARING
GAP BETWEEN TOP EDGE OF CYLINDER AND BOTTOM
EDGE OF PISTON SHALL BE MORE THAN 5 MM, 926.3.1.4

17. Pot Bearings used for the first time for Steel
Railway Bridge Girders of Indian Railways in
Mandovi and Zuari Bridges under Konkan Rly

18. Inspection
 Generally maintenance free
 However, they should be visually examined
during the inspection for any breakage in
dust seal and general cleanliness of the
bearing assembly.
 Evidence of free movement with temperature
and under loads to be seen

19. Maintenance Issues
 Extremely tight tolerance of manufacturing is
required to be maintained. Common issues:
– Leakage of the elastomer.
– Abrasion or wear of the elastomeric pad.
– Cracking of steel POT under transverse loads
 Normal maintenance is cleaning of
surrounding areas usually once a year.
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