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

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:

Minimum splines length to transfer the torque

	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

	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]