Movable
block systems
Bilge
block winches
Bilge
block chain
Garboard
shell assemblies
Upright
shell assemblies
Replacement
sheaves
Bilge
block hinges
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Crandall
adjustable sliding bilge block systems have been used by shipyards
throughout the world for decades. The system consists of crank-driven
cast iron winches secured to mounting plates attached to stands located
atop the cradle uprights (or atop the wing wall of a floating dry
dock). Upright shells located at the upright base at deck level serve
as idlers fairleading specially calibrated proof-coil bilge block
chain to the bilge blocks. Since the chain is arranged in an endless
system, the return movement is accomplished by the use of garboard
shells located adjacent to the drydock centerline. Crandall sliding
bilge block systems can be operated either from both docking platforms
of a marine railway or, in teh case of railway dry docks with side
transfer capabilities, special equipment is available for operation
from one side only. For floating dry docks, the wing wall or offset
back from the face of the wing wall so as not to interfere with line
handling, crane rails or other equipment. The winch stand sprocket
can be operated by a hand crank or power drive. A ratchet and pawl
mechanism on the winch provides a positive lock for holding the chain
stationary. |