PURPOSE: To obtain a smooth, nearly synchronized clutch connection without increasing the risk of erroneous shifting by increasing the number of interengageable clutch teeth provided in respective clutch members to be more than that of clutch teeth normally used in similar nonsynchronized positive clutch members.

CONSTITUTION: Backlash of the device is the sum of backlash due to spline connection between a clutch collar 50 and a main shaft 46, and backlash among the clutch collar, interengageable clutch teeth 208, 210 of respective gears. The number of clutch teeth 208, 210 is determined as a function of pitch radius 214 and backlash 216 when these are taken into consideration for durability. Based on these considerations, maximum number of clutch teeth or allowable, practically maximum number of clutch teeth is determined. If the number of clutch teeth defined as N, P is the number over 10, the pitch diameter is PD in inches, the number of clutch teeth has a relationship represented by N≥P.PD.