Hasluck, Paul N. (Paul Nooncree), 1854-1931, ed · Philadelphia, D. McKay · leaf 166
ropes. A block andtackle are secured to the top of the derrick,at the lower end of which a single block is required by men working the crab; Toprevent the truss swaying and doing damageduring ascent, it is guided by workmenholding ropes tied to it. The truss is nextplaced as nearly as possible in… … fixed. The other end of the tackle is con-nected to the truss, and the free end of the| cord passes through the top block and downthrough the single pulley fixed at the lowerend of the derrick, from which the cord iscontinued and connected to a crab. Thetruss is now gradually raised to the height 7…
Carpentry · Joinery
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