A reverted epicyclic gear train for a hoist block is shown in Fig. 13.39. The arm E is keyed to the same shaft as the load drum and the wheel A is keyed to a second shaft which car- ries a chain wheel, the chain being operated by hand. The two shafts have common axis but can rotate independently. The wheels B and C are compound and rotate together on a pin carried at the end of arm E. The wheel D has internal teeth and is fixed to the outer casing of the block so that it does not rotate. The wheels A and B have 16 and 36 teeth respectively with a module of 3 mm. The wheels C and D have a module of 4 mm. Find 1. the number of teeth on wheels C and D when the speed of A is ten times the speed of arm E, both rotating in the same sense, and 2. the speed of wheel D when the wheel A is fixed and the arm E rotates at 450 r.p.m. anticlockwise. A E D Fig. 13.39 B