Question

EXERCISES 400 120 us 3 The arrangements of a transmission brake is shown in Fig. 19.40. The arms are pivoted at o, and O2 and when force is applied at the end of a hand lever, the screw AB rotates. The left and right hand 120 force on the hand lever is applied 400 mm from the axis of the screw The drum is 240 mm in diameter and the angle subtended by each is 90°. The screw has six square threads with a mean diameter of 20 mm and a lead of 55 mm. Assuming a coefficient of friction for the braking surface as 0.3 and for the threads 0.15, determine the force on the hand lever required to set the brake when the torque on the drum is 245 N-m. 40 40 Ans. 865 N All dimensions in mm. Fig 19.40

The arrangement

Answer 1

Toaque on doum T= 245 N-m. he ngntal fae t t suare daum das m = 240mm di arrete) er Given esse-shoe span ave Foom figure ub 120 120 u5 45-1843 40 ," 26.56 = -Angle -fac-Isi vote to matimam Pesue Point

0.3 sin ea 245 x Sin 4o C0.24) (03(012)Cos(26,0)-Cesgo force is given b) actuati ng NO co the ビ、ニ MONent acting on the tea ding shoe due to Nmal ce sin Oo up- t 26.5-mm = 0-1265 m

父(2-26-56江 o-sin(26-56) Moment acting on leoding shes duo crC 03x 6418 x10x o s 110 0.1263 MF 539, 5 - 02 F8.87 KN. (Acasing force rtkis is the t-on ce deg utbedat-the sCoeco. NcLs To ind the face deqd at on hed leven is iven the scroeD 0.4

To find tog cte -terr(0.is) 0--terni(M) 8.53 N-. m. ,T = 56.85 ON Y12.13 O M Arser may b coreng due to mistakes nsaxs may be corong due to mislakes ca cla ion but the paoceduse aoas Corbect