Tooth interference in an external involute spur gear pair can be reduced by

Two mating spur gears have $$40$$ and $$120$$ teeth respectively. The pinion rotates at $$1200$$ $$rpm$$ and transmits a torque of $$20N.m.$$ The torque transmitted by gear is

The minimum number of teeth on the pinion to operate without interference in standard full height involute teeth gear mechanism with $${20^ \circ }$$ pressure angle is

Large speed reductions (greater than $$20$$) in one stage of gear train are possible through