A shaft of diameter 10cm transmits a torque of 600 kgf m. A flanged coupling is keyed to the shaft by means of a key 2.8 cm wide $\times$16cm deep $\times$ 10 cm long. The coupling has 6 bolts of 2cm diameter symmetrically arranged along a bolt circle of diameter 30 cm. Calculate the shearing stresses in the shaft, the key and the bolts.