23-07-2012, 10:39 AM
Dismantling of 18.3m Plate Girders – A case study
Why required to do so
In Regirdering Using Portals and Dip Lorry
Method, the old girder is cut into two pieces and
pushed apart to make space for placing new
girder.
Functional Requirement
Carrier should be capable of
(a) lifting both leafs one end
(b) holding firmly two leafs
© moving by manual force
Equipment Development
Tools & Plant
Winches(2Nos), Wire ropes for winches (suitable
length), Wire ropes 4m(2Nos), Chain block
10t(4Nos), Chain block 5t(4Nos), Hyd. Jack 30t(4Nos),
Mech. Track jack 15t(2Nos), Rail pieces 2.5m(4Nos),
Crow bars (8Nos), Gas Cutting Set(2Nos).
Process and Precautions
Bringing Leaf Carrier onto track
Towing Leaf Carrier to the span
Lifting the leafs
Fixing leafs to carrier brackets
Carrying leafs to disposal site
Arrangement at disposal site
Removing Leaf Carrier Portal
Removing Cess side leaf
Removing other side leaf
Removing Traffic block
Bringing Leaf Carrier onto track
Leaf carrier is pulled from side stage on to track by
skidding on two rails placed across track. Rollers
are fixed in the frame bottom of dip lorry to facilitate
this. Care should be taken during pulling to prevent
carrier from going onto other line.
After carrier wheels are on track, carrier is slightly
lifted and skid rails are removed and carrier is
lowered onto running rails.
Towing Leaf Carrier to the span
Both carriers are then towed to the span.
Being high center of gravity, care should be taken
to avoid overturning of portal. Pulling should be
slow and jerk free motion. No object should be
there above rail level in near vicinity, which can get
entangled to the dip lorry bottom frame.
After reaching span, place carrier such that carrier
brackets and leaf brackets are in same plane.
Place wooden wedges below wheels to prevent
dislocation of dip lorry during lifting.