Spur Gear Strength Calculation According to Merrit

Based on the fixed-end beam calculation. Anticipates that the total circumferential force can only be carried by one tooth.

Allowable load

F all = π c min b w m μ≥ F t

where:

	c_min= min (c_b, c_c)	minimum tooth allowable stress
	b_w	operating tooth bearing width
	m	module
	μ	factor of dependence on the precision degree (table value)
	F_t	circumferential force acting on the teeth

Safety factor

S = F all / F t

Bending factor

where:

	σ _Ab	allowable stress in bending (material property)
	r_b	speed bending factor (table value)
	y_b	shape bending factor (table value)

Contact factor

where:

	σ _Ac	allowable stress in contact (material property)
	r_c	speed pressure factor (table value)
	y_c	shape pressure factor (table value)
		size factor