E/MJ : engineering and mining journal . Texasfield, the prices being for labor only, including doublingthe legs and putting on double guy wires: Cost$ Cost Size ofDerrick, Ft $ 8590 112 Derricks are usually torn down by contract also, andin this work it pays to employ skilled labor because ofthe greater saving of material. Croum Block—Crown blocks are made of wood, eitherhard or soft, or steel I-beams, and steel pulleys. Theprincipal members, four in number, are arranged par-allel to each other, and are held apart by spacing I-beams are 8, 10 or 12 in
E/MJ : engineering and mining journal . Texasfield, the prices being for labor only, including doublingthe legs and putting on double guy wires: Cost$ Cost Size ofDerrick, Ft $ 8590 112 Derricks are usually torn down by contract also, andin this work it pays to employ skilled labor because ofthe greater saving of material. Croum Block—Crown blocks are made of wood, eitherhard or soft, or steel I-beams, and steel pulleys. Theprincipal members, four in number, are arranged par-allel to each other, and are held apart by spacing I-beams are 8, 10 or 12 in. high. The pulleys, fivein number for rotary work, run vertically betweenthese main members, and are arranged like the five-spots on a playing card. Pulley sizes vary, a diameterof 22 in. being common. The steel crown block is an im-provement on the older wooden crown block. Swivel—The rotary hydraulic swivel is so constructedthat it can support the entire weight of the string,permit the stem to revolve, and allow water or mud to. Side End f ish-Tail Bit via. 2. HYDRAULIC SVi^IVEL, LTSBD IN ROTARY METHODFIG. 3. FISH-TAIL BIT be pumped down through it under high pressure with-out leaking. Fig. 2 shows one form of swivel in is suspended from the C-hook under the travelingblock by the bail A, and this, in turn, supports the trun-nion B. On the trunnion is placed the bearing race (designedfor ball or cone bearings in different makes), bearings 174 Engineering and Mining Journal Vol. 108, No. 5 Unside at C, Fig. 2), and bearing seat. The bearingsat this point must sustain the entire weight of thedrill stem. Water or mud from the slush pit is pumpedinto the gooseneck E, from which it passes down throughthe standpipe F, into the grief stem at its point of con-nection D, and so into the drill stem. The swivel is tightly held together by various lockcollars, permitting the revolution of the standpipe, yetmaking a water-tight connection with the gooseneck,which, being connect
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectmineralindustries
