The sewing machine needle bar mechanism is shown in Fig.2.64(a). Crank 2 rotates at \(450 \mathrm{rpm}\).
Determine the velocity of the needle at \(D\).
\(O_{1} A=15 \mathrm{~mm}, O_{2} B=25 \mathrm{~mm}, A B=65 \mathrm{~mm}, B C=20 \mathrm{~mm}, C D=60 \mathrm{~mm}\) and \(\angle O_{2} B C=90^{\circ}\).

Transcribed Image Text:

13 40 mm 23 30% 656 15 45 C (b) Circle diagram 15 (a) Locating instantaneous centres Fig.2.64 Sewing machine needle bar mechanism