The disk sander shown in Figure 1 uses a 125hp motor with a

The disk sander shown in Figure 1 uses a 1.25-hp motor with a full load speed of 900 rpm Determine (a) what force F should be applied to develop the full capacity of the motor and (b) the magnitude and location of the maximum principal stress in the shaft. Assume a coefficient of friction of 0.80 between the sander and wood. (Ans. (a) 19.9 lb and (b) 3345.87, -333.47 psi at B)

Solution

solution

power = 2 pi N T / 60

where power = 1.5 hp = 932.1248 Watts

N = 900 r.p.m

so, T = ( 932.1248 X 60 ) / (2 X pi X 900 )

= 9.89

Torque = force X distance

9.89 = force X 0.5

force = 19.8 lb