A pair of spur gears with module 5 mm and a center distance

A pair of spur gears with module 5 mm and a center distance of 450 mm is used for a speed reduction of 5 : 1. The number of teeth on pinion is ______ .

Given speed Ratio = 5: 1

5	=	T₂	=	d₂
1	=	T₁	=	d₁

⇒ d₂ = 5d₁

centre distance =	d₁ + d₂	= 450
	2

⇒ d₁ + d₂ = 900
⇒ 5d₁ + d₁ = 900
⇒ d₁ = 150

m =	d₁	⇒ T₁ =	1500	= 30
	T₁		5