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Figure 11.1 – Hoisting system
In most cases the crown block is more loaded than the
travelling block. Taking into account that hoisting load applied to
ropes is always identical, more than 200 000 pounds for the whole
system, it is clear that crown block is loaded with 160 000 pounds
(8 lines, 20 000 pounds per one) and travelling block is loaded
only with 120 000 pounds (6 lines, 20 000 pounds per one).
Crownblocks
A crownblock, as a permanent hoisting system sheaf, is
tightly attached to the undercrownblock area, to the tower drilling
system or to the derrick. Block strings are very often part of the
tower structure than separate details.
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