Regarding synchronizer rings, which technician's statement is correct?

The correct answer is that both Technician A and Technician B are correct in their statements about synchronizer rings.

Technician A describes how synchronizer rings function to equalize the speeds of the synchronizer assembly and the gear being engaged. This is a fundamental role of synchronizer rings, as they facilitate smooth gear shifting by ensuring that the speeds match, preventing grinding and allowing for effective engagement of the gears.

Technician B correctly mentions that synchronizer rings also serve to block the synchronizer sleeve during shifts, albeit briefly. This blocking action prevents the engagement of gears at inappropriate speeds, which helps in coordinating the movement of the synchronizer sleeve and the gear being shifted into, ensuring that the engagement happens at the right moment and reduces wear on the transmission components.

Together, both statements reflect important functions of synchronizer rings in manual transmissions, underscoring their role in achieving smooth shifting and protecting the transmission system from damage caused by mismatched speeds.