A crane brake is lowering the load shown in Fig. 1 at a speed of 5.5 m/min. The motor shaf...

A crane brake is lowering the load shown in Fig. 1 at a speed of 5.5 m/min. The motor shaft is connected to the cable drum shaft by a gear train with a 130:1 ratio. Assume that the gears and bearings are frictionless. The brake drum rotates at one-half motor speed and is 400 mm in diameter; the lining is 75 mm wide; μ is equal to 0.2. The shoes and levers are arranged as in Problem 1. Find the value of pmax and the value of P1 for α1 = 1 and α2 = 1/3.

Figure 1

Problem 1

Make an exploded view of the brake in Fig. 2 showing the forces required for the equilibrium of each part. Write the expression for the torque in terms of μ, P1, r, a1, and a2.

Figure 2