Power Transmission Systems | Transmission System Parts:

Aka Blocker or Baulk ring. It can relieve the speed diff. in selector and gear.

The application is the same as Synchronizer ring but the material is steel and has better strength.

The application is the same as Synchronizer ring but the design is little different.

The fork is the selector of sleeve slides between two gears in order to lock either gear to the shaft.

The key is the blocker on the synchronizer rings that can hold the sleeve in correct shift.