Question

3 MEE231V OCT/NOV 2018 Question 3 Figure 2 shows a brake drum that is rotating anticlockwise The brake arm ABF pivots at B and the braking force of 40 N is applied at F The drum has a diameter of 900 mm and rotates at 300 rev/min The coefficient of friction between the brake drum and the brake band is 0,35 180 mm 780 mm A B 60° 604 Figure 2 Calculate 31 The length of the arc of contact and the tensions in the two sides of the brake band (10) 32 The power absorbed by the brake (4) 33 The reaction of the pivot at B (6) [20]

Answer 1

Soln B l - 0.35 A K 180mm ad A 780 mm 60 160 TI XT2 F-40N N = 300 rpm ㅋ D = goomm 0-2400 ④ length of arc = RO = 450X2407 180 Lc =1884.95mm a ello N ut LH I = e 10:358840x-IT 180 T2 Ti = Tz (4:33) FBD OF A B Fs A * 190mm < 780 mm X 600 "YON Ti EMA ft, 4n609 )x 180 = - 40 x960 To =-846.34N 7,5-1466.44N

the brake's power cebsorbed by 7 (5.-72) XR =-(1066.64-246134)X:45 Ty = -369.13 N-m Power = Ty XW to : 2 T X 300 60 - 31.41 rades ; -369.13X31:41 Power absorbed = 11.6 KW 3 Recetion of the pivot cet B RB x = TEC0 5600 Rby = Tz H 260° I RB = 72 = 246.34 N be