For the system shown in Fig. 5, the input is the small 1cm diameter capstan. The cable is terminated and tensioned on the 8cm output. The friction coefficient between the cable and the capstan is 0.7. 

Given a cable pre-tension of 20N, what is the preload force experienced by the shaft supporting the input capstan?

Given a cable pre-tension of 20 N and between 2 and 3 wraps of the cable about the input capstan, how much torque can be transmitted to the output?

 

M 8 cm dia 45 deg 1 cm dia 45 deg Figure 5: Capstan drive, single stage.