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

Machining of complex shapes on $$CNC$$ machines requires

The temperature of a carburizing flame in gas welding is _______ that of a neutral or an oxidizing flame.