What is the main purpose of a brake proportioning valve?

The main purpose of a brake proportioning valve is to balance the brake pressure between the front and rear brakes. In a vehicle, the front brakes typically handle a larger proportion of braking force due to weight transfer during deceleration. Without a proportioning valve, the rear brakes could lock up too early, leading to instability and potential loss of control.

The brake proportioning valve adjusts the pressure applied to the rear brakes based on various factors, ensuring that braking force is distributed effectively between the front and rear systems. This helps maintain vehicle stability during braking, allowing for safer stopping distances and improved handling characteristics. By ensuring that the rear wheels do not engage too aggressively relative to the front, the proportioning valve plays a critical role in the overall performance and safety of the braking system.