Budynas-Nisbett:Shigley's Ill.Design of Mechanical 8.Screws,Fasteners,and T©The McGraw-Hil 403 Mechanical Engineering Elements the Design of Companies,2008 Design,Eighth Edition Nonpermanent Joints 400 Mechanical Engineering Design Table 8-3 d,in 子各是之吾石1 1H1为1是2223 Preferred Pitches for Acme Threads P.in 6日立b日名名古多日子日行五 are sometimes modified to a stub form by making the teeth shorter.This results in a larger minor diameter and a somewhat stronger screw. 8-2 The Mechanics of Power Screws A power screw is a device used in machinery to change angular motion into linear motion,and,usually,to transmit power.Familiar applications include the lead screws of lathes,and the screws for vises,presses,and jacks. An application of power screws to a power-driven jack is shown in Fig.8-4.You should be able to identify the worm,the worm gear,the screw,and the nut.Is the worm gear supported by one bearing or two? Figure 8-4 The Joyce wormgear screw jack.(Courtesy Joyce-Dayton Corp.,Dayton,Ohio.)Budynas−Nisbett: Shigley’s Mechanical Engineering Design, Eighth Edition III. Design of Mechanical Elements 8. Screws, Fasteners, and the Design of Nonpermanent Joints © The McGraw−Hill 403 Companies, 2008 400 Mechanical Engineering Design Figure 8–4 The Joyce worm-gear screw jack. (Courtesy Joyce-Dayton Corp., Dayton, Ohio.) are sometimes modified to a stub form by making the teeth shorter. This results in a larger minor diameter and a somewhat stronger screw. 8–2 The Mechanics of Power Screws A power screw is a device used in machinery to change angular motion into linear motion, and, usually, to transmit power. Familiar applications include the lead screws of lathes, and the screws for vises, presses, and jacks. An application of power screws to a power-driven jack is shown in Fig. 8–4. You should be able to identify the worm, the worm gear, the screw, and the nut. Is the worm gear supported by one bearing or two? d, in 1 4 5 16 3 8 1 2 5 8 3 4 7 8 1 11 4 11 2 13 4 2 21 2 3 p, in 1 16 1 14 1 12 1 10 1 8 1 6 1 6 1 5 1 5 1 4 1 4 1 4 1 3 1 2 Table 8–3 Preferred Pitches for Acme Threads