574 書名： Essentials of Mechanical Engineering Design, 1/E 作者： Shigey Mischke Budynas 書號： MX0398
575 Interested in : 1.The actuating force 2.The torque transmitted 3.The energy loss 4.The temperature rise
576
577 Normal force on the pad Moment due to normal force
578
579
580
581
582
583
584
585
586 Expanding ring clutch Centrifugal clutch Magnetic clutch Hydraulic and pneumatic clutch
587 Expanding ring
588 Magnetic clutch
589 Hydraulic and pneumatic clutch
590 Assumptions: 1.The pressure at any point on the shoe is proportional to the distance from the hinge pin, being zero at the hill. 2.The effect of the centrifugal force is neglected. 3.The shoe is rigid. 4.The friction coefficient does not vary with pressure.
591 Infinitesimal rotation deformation
592 Interesting and useful characteristics: 1.The pressure distribution is sinusoidal with respect to angle. 2.If the shoe is short, the largest pressure on the shoe is pa occurring at the end of the shore. 3.If the shoe is long, the largest pressure on the shoe is pa occurring at the 90 o.
593
594 Clockwise rotation Self energize Torque applied to the drum Hinge ping reaction
595 Clockwise rotation set
596
597
598
599
600
601
602
603
604 Clockwise rotation Counter clockwise rotation Centrifugal force is more important
605
606 To make the moment of friction eq. 0 to make even wear
607 If we chose an a which can make Rx=-N and Ry=-fN. Which imply that
608
609 Vertical direction Horizontal direction
610
611
612 Uniform wear dF=2πprdr
613 Uniform pressure Eq. (11-23) can be written as:
614 Eq. (11-28) can be written as: Old clutch new clutch
615 Caliper disk break
616
617 Uniform wear P=p a r i /r Equivalent radius Location of acting force Uniform pressure Equivalent radius Location of acting force
618
619
620
621
622
623
624 Uniform wear Uniform pressure
625 Uniform wear Uniform pressure When two axis's have same speed
626 In BTU In SI unit
627
628
629 For I 1 =I,I 2 =0 For single stop For steady state
630
631
632
633
634
635
636
637
638
639 At θ=θ 1 At θ=θ 2 Coefficient of speed fluctuation where
640
641
642
643
644