A pin-type synchronizer mechanism for first and second axially spaced apart gears mounted for rotation and secured against axial movement on a shaft having an axis about which the gears and the shaft rotate, the mechanism comprising:
- gear friction and jaw means affixed to each gear, the friction means engagable with first and second axially spaced apart and axially movable friction means for respectively synchronizing the first and second gears with the shaft, and the gear jaw means engagable with axially movable jaw means;
- the shaft including a plurality of circumferentially spaced apart, axially extending, external spline teeth having flank surfaces slidably and continuously mating with the flank surfaces of internal spline teeth of the movable jaw means, radially inner extents of the internal spline teeth defining an inside diameter thereof;
- a flange extending radially between the first and second movable friction means for axially moving the axially movable friction and jaw means into said engagement in response to an axially bi-directional shift force applied to the flange, means securing the flange against axial movement relative to the axially movable jaw means;
- blocker means operative when engaged for preventing engagement of the jaw means prior to the synchronizing, the blocker means including a plurality of circumferentially spaced pins rigidly extending axially from the first and second movable friction means and into openings of the flange, each of the pins having axially spaced apart blocker shoulder engagable with blocker shoulders defined on opposite sides of the flange and about the associated opening;
- pre-energizer means for engaging either one of the first and second friction movable means with an engaging force in response to initial axial movement of the flange by the shift force from a neutral position toward one of the gears, for engaging the blocker means in response to engagement of the friction means producing a synchronizing torque transmitted to the flange via the pins, and for transmitting the shift force to the engaged friction means via the engaged blocker means to increase the engaging force of the engaged friction means;
- characterized by;
- the means securing the flange and the flange including stop means for limiting circumferential movement of the flange relative to the axially movable jaw means;
- first and second axially spaced apart recesses in the shaft splines defining annular grooves separated by post-like portions of the shaft splines therebetween, the recesses having a minimum outside diameter greater than the inside diameter of the internal spline teeth of the movable jaw means, a first common circumferentially facing side of several of the post-like portions including first and second self-energizing ramp surfaces forming angles less than ninety degrees relative to a plane normal to the shaft axis;
- several reaction means extending radially inward from the flange and received in spaces between the shaft splines at position adjacent the post-like portions, the reaction means having an inside diameter greater than the minimum outside diameter of shaft spline recesses, the reaction means including third and fourth self-energizing ramp surfaces respectively for mating engagement with the first and second ramp surfaces of the post-like portions in response to synchronizing torque in at least one direction from the engaged friction means respectively associated with the first and second gears to produce axial additive forces on the flange in a direction of the shift force for increasing the engaging force of the respective friction means.