Which component is used to modulate rear brake pressure to prevent wheel lock?

Prepare for the Automotive Service Technician Period 1 exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Reducing rear brake pressure during heavy braking keeps the rear wheels from locking and helps maintain steering control. This balance is provided by the proportioning valve, which sits in the rear brake circuit and trims how much hydraulic pressure reaches the rear brakes as you apply the pedal. As master-cylinder pressure rises, the valve limits rear-side pressure so the front brakes—sharing more of the braking load due to weight transfer—do most of the stopping while the rear wheels stay under control. The other items have different roles: a metering valve delays brake application in some front-disc/rear-drum setups for smooth operation, a pressure differential valve is used in ABS to detect wheel-lock tendencies, and a lathe-cut seal is just a type of seal, not a braking pressure modulator.