System for preventing gear hopout in a tooth clutch in a vehicle transmission

System for preventing gear hopout in a tooth clutch in a vehicle transmission, comprising an input shaft that at least in some states of operation is connected to a prime mover, and an output shaft connected to driven wheels of the vehicle, the tooth clutch comprising an engaging sleeve having sleeve clutch teeth that can selectably be brought in and out of an engaged state with mating clutch teeth by axial displacement of the engaging sleeve, the tooth clutch causing in the engaged state a first rotating system to rotate in unison with a second rotating system, the sleeve clutch teeth and the mating clutch teeth having a clutch teeth pitch diameter, the sleeve clutch teeth having sleeve driving tooth flanks in contact, in the engaged state when power is transferred from the input shaft to the output shaft, with mating driving tooth flanks of the mating clutch teeth, the sleeve clutch teeth further having sleeve braking tooth flanks in contact, in the engaged state when power is transferred from the output shaft to the input shaft, with mating braking tooth flanks of the mating clutch teeth, the sleeve driving tooth flanks and the mating driving tooth flanks substantially being back-tapered with a driving back-taper angle, the sleeve braking tooth flanks and the mating braking tooth flanks substantially being back-tapered with a braking back-taper angle, the engaging sleeve having sleeve spline or gear teeth that are in mesh with mating spline or gear teeth on at least one mating rotating part, the sleeve spline or gear teeth and the mating spline or gear teeth having a spline teeth pitch diameter when meshing, the sleeve clutch teeth and the mating clutch teeth having a clutch coefficient of friction for axial motion of the engaging sleeve, and when meshing, the sleeve spline or gear teeth and the mating spline or gear teeth (110, 210) having a spline coefficient of friction for axial motion of the engaging sleeve, wherein a tangent function for at least one of the driving back-taper angle and the braking back-taper angle is larger than an average value of the clutch coefficient of friction and the spline coefficient of friction multiplied by a sum of unity and a ratio of clutch teeth pitch diameter and spline teeth pitch diameter.