In engaging (connecting) a dog clutch by operating a synchromesh mechanism, when there occurs an uplock at the time when a first pressing force is caused to act on a hub sleeve, tooth tips of spline teeth of the hub sleeve contact with tooth tips of spline teeth of a synchronizer ring, and these spline teeth cannot be engaged. However, when a second pressing force is caused to act on the hub sleeve, the uplock is easy to be released. In addition, when torque from an engine is caused to act on the hub sleeve, a displacement is caused to occur in a rotation direction between the mutually contacting spline teeth. Thus, the uplock is reliably released.

A synchromesh mechanism is activated when cancelling a disconnection state, and, when an electronic control unit determines that a rotation speed of an input shaft has been synchronized with a rotation speed of a first ring gear, a second intermeshing clutch is engaged, and then a first intermeshing clutch is engaged. For this reason, in the first intermeshing clutch, a decrease in the rotation speed of the first ring gear is suppressed as a result of engagement of the second intermeshing clutch. This suppresses out of synchronization between the rotation speed of the first ring gear and the rotation speed of the input shaft at the time when the first intermeshing clutch is engaged.

A synchronizer system and method allow synchronization of a plurality of rotating parts by determining a measured or calculated starting relative speed of the plurality of rotating parts, and based on the starting relative speed selecting a predetermined synchronizer force profile from among a plurality of candidate profiles for synchronizing the plurality of parts prior to engagement. The selected profile is retrieved and applied to a synchronizer between the plurality of parts to be engaged, and when the relative speed between the plurality of parts to be engaged becomes substantially zero, the plurality of parts can then be engaged to one another.

In engaging (connecting) a dog clutch by operating a synchromesh mechanism, when there occurs an uplock at the time when a first pressing force is caused to act on a hub sleeve, tooth tips of spline teeth of the hub sleeve contact with tooth tips of spline teeth of a synchronizer ring, and these spline teeth cannot be engaged. However, when a second pressing force is caused to act on the hub sleeve, the uplock is easy to be released. In addition, when torque from an engine is caused to act on the hub sleeve, a displacement is caused to occur in a rotation direction between the mutually contacting spline teeth. Thus, the uplock is reliably released.