Final answer:
Both Technician A and Technician B are correct regarding the disadvantages of drum brakes: poor heat dissipation leading to brake fade and the lack of self-adjustment leading to inconsistent braking.
Step-by-step explanation:
The question poses a scenario discussing the disadvantages of drum brakes compared to disc brakes. Both Technician A and Technician B make claims about the drawbacks of drum brakes. Technician A says that drum brakes have poorer heat dissipation and less fade resistance than disc brakes. Technician B says that drum brakes lack self-adjustment without special linkage and have a greater tendency than disc brakes to pull and grab.
Technician A's statement is correct because drum brakes are enclosed, which impedes heat dissipation, leading to higher temperatures and a higher likelihood of brake fade during intensive use such as prolonged downhill driving. This is significant, as poor heat dissipation can lead to overheating, as when the brakes of a truck become visibly smoking due to the mechanical equivalent of heat, converting kinetic and potential energy into thermal energy in the brake material.
Technician B's observation is also correct; drum brakes generally require a self-adjusting mechanism to maintain proper shoe-to-drum clearance as the brakes wear. Without it, they do not self-adjust like disc brakes. Furthermore, improper adjustment or wear can lead to inconsistencies in braking force, causing the vehicle to pull to one side or experience brake 'grab.'