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Illustrated Sourcebook of Mechanical Components Part 4

Tham khảo tài liệu 'illustrated sourcebook of mechanical components part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 5-16 F - - F 12 sin a Numerical example A centrifugal clutch shoe has a radius of 5.25 in. and a width of lining of 2.50 in. Lining pressure is not to exceed 100 psi. Angular length of lining is Ó 108 deg and the link is at an angle of a 48 deg. The shoe is pivoted at a distance h of 4 in. from the center. Total inward spring force of both springs is 15 lb. Weight of shoe is 3 lb with its center of gravity at a radius of 4.6 in. As there are linings on the market with a different coefficient of friction for values of fl of 0.1 0.2. 0.3 0.4 and 0.5 find the corresponding values of forces Q R and F F. Find the torque T the corresponding slipping rpm and the horsepower per shoe. Plot the curve for hp vs fl to determine the best value for fl. Solution By Eq 7 fl 4 5.25 0.80902 4 1.88496 0.95106 tan e 4 1.88496 0.95106 1.511m By Eq 2 A ị 2.5 5.25 100 2.83602 cos e - 1861 cos e By Eq 3 Nw 612.9 sin 9 2. Floating-link design Clutches 5-17 By Eq 6 T 2m 2.5 5.25 2 100 0.80902 cos 0 11 149 X cos é From Eq 10 Then n - 60 9.55 w 50.5 Fe Z7T also Tn hp 10WQ The calculations are best carried out in tabular form see table . Thus for the case of ịi 0.1 tan d 0.1511 0 8 35.6 cos 0 0.9888 N -1861 0.9888 -1840.2 1b N -612.9 0.1494 -91.6 1b By Eq 4 5 and 8 F -0.1 -91.6 9.16 1b Fw 0J -1840.2 -184.0 lb Q V 1840.2 9.16 2 91.6 184.0 2 1852 lb By Eq 9 a _ -275.6 _ n 1cncf tan 3 1091 0.15052 lool 3 8 33.6 By Eq 11 and 12 R 371 lb sin 48 Ff F -F 33 1583 lb sin 48 F 1583 15 1598 lb Thus T 11 149 0.1 0.9888 1102 Ib-in. n 50.5 V1598 2019 rpm 4. Variation of horsepower with coefficient of friction for the floating-sink clutch analyzed in the numerical example. Note that best gripping power ss obtained with shoe-linings having a coefficient of about 0.35 . Calculations for various linings Li tan 0 0 N Fr F c N F . Nir4-F v .- 2 o 0.1 0.15112 8 35.6 -1840.2 -91.6 9.2 -184.0 -1831.0 -275.6 75 960 1852 0.2 0.30225 16 49.0 -1774.1 -177.3 35.5 -354.8 -1738.6 532.1 283 130 1818 0.3 .