. American engineer and railroad journal . l2 (100 X 78) + 121 = 7921 562 = (56 — 6) (56 + 6) + 6* (50 X 62) + 36 = 3136 21^2 = (2VA — V/i) (2V/2 + V/2) + V/2* (20 X 23) + 2J4 = 462J4 1922 = (192 + 8) (192 — 8) + 82 (200 X 184) + 64 = 36864 (1)(2)(3)(4) JIB CRANE DESIGN. (From Theo. F. H. Zealand. Whiting Foundry EquipmentCompany, Harvey, III.) Frequently motive power officials, when contemplating the pur-chase of jib crane equipment, prefer to submit designs of theirown upon which crane manufacturers are invited to offer quota-tions ; often cranes built from the designs thus submitted wouldbe
. American engineer and railroad journal . l2 (100 X 78) + 121 = 7921 562 = (56 — 6) (56 + 6) + 6* (50 X 62) + 36 = 3136 21^2 = (2VA — V/i) (2V/2 + V/2) + V/2* (20 X 23) + 2J4 = 462J4 1922 = (192 + 8) (192 — 8) + 82 (200 X 184) + 64 = 36864 (1)(2)(3)(4) JIB CRANE DESIGN. (From Theo. F. H. Zealand. Whiting Foundry EquipmentCompany, Harvey, III.) Frequently motive power officials, when contemplating the pur-chase of jib crane equipment, prefer to submit designs of theirown upon which crane manufacturers are invited to offer quota-tions ; often cranes built from the designs thus submitted wouldbe unsafe in the service for which they are intended, the weakmember of the design being the jib C. The stresses in this member are imposed as follows: Bending due to the load W. Bending due to the weight of the jib. Compression due to the tension in A. All these produce compression in the top flange of the beam C,which compression is a maximum when the load is placed ap-proximately two-thirds of. the jib length from the mast B. These. calculations are usually made with sufficient accuracy but, whenchoosing the size of the beam or channel for the jib C, no ac-count is taken of the tendency of the top flange of the beam todeflect laterally due to the compression. To guard against thisthe allowable compressive stress in this member must be reduced,necessitating the use of a larger size beam than would otherwisebe required. The allowable compression per square inch of cross sectionalarea is given by the following empirical column formula, where and b equals the flange width of the beam, both dimensions ex-pressed in inches; the working compressive stress used through-out the design being 10,000 pounds per square inch: p 11 iO V 1 -I- — 3000 V P is the allowable compression per square inch in the topflange. No claim is made to originality in connection with the formulagiven. It is to be found in any good structural steel hand-book, as P = [8000 1 + 18001 F giving a reduced al
Size: 1566px × 1596px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
