Parallel Spline Calculation Formulas in Metric Units

Transferred torque

where:

	P	transferred power [kW]
	n	speed [rpm]

Pressure on groove supporting surface

1. shaft inside diameter d _h > 0

a)

b) if d _min ≤d _h -> d _min = 1.1 d _h [mm]

c) if d _min ≤ 1.5 d _h -> d _min = 1.5 d _h [mm]

2. shaft inside diameter d _h = 0

where:

	d min	minimal shaft diameter [mm]
	d h	shaft inside diameter [mm]
	T	torque [Nm]
	K a	application factor
	K f	fatigue-life factor
	S v	desired safety
	τ Al	Allowable Shear Stress

Minimum splines length to transfer the torque

1. Fixed connection:
2. Flexible connection:
where:

	T	torque [Nm]
	K a	application factor
	K f	wear-life factor
	K w	application factor
	K m	load distribution factor
	S v	desired safety
	d s	middle diameter = (D + d) / 2 [mm]
	D	outside diameter of groove section [mm]
	d	inside diameter of groove section [mm]
	N	number of grooves [-].
	h	height of groove = (D - d) / 2 [mm]
	s	chamfer
	h st	connection height h st = h - 2 s [mm]
	p Dmin	allowable pressure on supporting surface of shaft or groove [MPa]

Allowable pressure

1. Fixed connection:
2. Flexible connection:
where:

	T	torque [Nm]
	K a	application factor
	K f	wear-life factor
	K w	application factor
	K m	load distribution factor
	S v	desired safety
	d s	middle diameter = (D + d) / 2 [mm]
	D	outside diameter of groove section [mm]
	d	inside diameter of groove section [mm]
	N	number of grooves [-].
	h	height of groove = (D - d) / 2 [mm]
	s	chamfer
	h st	connection height h st = h - 2 s [mm]
	l f	active key length [mm]

Strength Check

p _min ≤ p _ds

p _min ≤ p _dh

where:

	p min	minimal calculated h/2 pressure [MPa]
	p ds	allowable pressure in shaft [Mpa]
	p dh	allowable pressure in hub [Mpa]