To study the variations of friction torque and gaps during the disengaging process of a wet multi-disc clutch with different spline friction coefficients

a comprehensive disengaging dynamic model is proposed

and the non-uniformity coefficient is employed to characterize the disengaging uniformity. The results show that during the disengaging process

the friction pair gaps first increase slowly

then increase rapidly

finally stabilize after fluctuating. The disengaging process ends when the friction pair gaps stabilize

but the spline friction coefficient has slight effect on the disengaging time. When considering the spline friction

the disengaged gaps are no longer uniform

but decrease from the first friction pair to the sixth friction pair in sequence. Moreover

the increase of spline friction coefficient significantly deteriorates the disengaging uniformity. Finally

with the increase of spline friction coefficient

the initial value and change rate of contact torque decrease

while the final value of hydrodynamic torque increases. Therefore

the decrease of spline friction coefficient promotes the uniform disengaging of friction pairs and reduces the drag torque.