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Illustrated Sourcebook of Mechanical Components Part 3

Tham khảo tài liệu 'illustrated sourcebook of mechanical components part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 4-16 2 SQUARE and RECTANGULAR SHAFTS Torque T in.-lb Max shear stress f psi 2 000 000 10 000 1 000 000 Example 4 finds s for square shaft that win transmit 17 300in.-lb torque at 18 000psi shear stress. Example 5 finds A for rectangular shaft for ratio A B - 1.20 100 000 10 000 1000 Square side s in. c-5.0 4.0 3.0 Major side A in. 10.0 -3 5.0 Ratio A B r 5.0 20 000 2.0 2.0 1.0 Example 5 1.0 0.5 0.7 0.5 2.0 1.0 30 000 Shaft section Location of max shear Torque formulas T 1 -- S -JL Middle of sides 0.208S3f 1 A r Midpoint of major sides A2B2f 3A I.8B 40 000 50 000 200 60 000 Shafts Couplings 4-17 Critical Speeds of End Supported Bare Shafts L. Morgan Porter This nomogram solves the equation for the critical speed of a bare steel shaft that is hinged at the bearings. For one bearing fixed and the other hinged multiply the critical speed by 17s Ổ. For both bearings fixed multiply the critical speed by 2.27. The scales for critical speed and length of shaft are folded the right hand sides or the left hand sides of each are used together. The chart is valid for both hollow and solid shafts. For solid shafts D2 0. 50 000 8 000 7 000 40 000 6 000 5 000 46.886 IQ 5 P 0 Ư where D - 0 D Dz ID 30 000 20 50 4 000 9 000- Exomple - D 6.3in. Dz 5.8 in. d d 8.56 L l30in. Nc 2 375rpm 8 000 7 000- For Aluminum multiply values of N by1.0026 For Magnesium multiply values of Ncby 0.9979 6 000--- 1 000 15 4-18 Torsional Strength of Shafts Formulas and charts for horsepower capacity of shafts from 1 2 to 2 1 2 inch diameter and 100 to 1000 rpm. Douglas c. Greenwood For a maximum torsional deflection of 0.08 per foot shaft length diameter and horsepower capacity are related in d 4.6 where d shaft diameter in. hp horsepower I shaft speed rpm. This deflection is recommended by many authorities as being a safe general maximum. The two charts are plotted from this formula providing a rapid means of checking transmission-shaft strength for usual industrial speeds up to 20 hp. Although shafts .