The hydraulic system combination valve primarily performs three crucial functions in a vehicle's braking system: proportioning, metering, and pressure warning.
Here's a breakdown of each function:
-
Proportioning: The proportioning valve regulates pressure to the rear brakes, preventing them from locking up prematurely, especially during hard braking. This helps maintain vehicle stability and control. Without it, the rear wheels could lock up before the front wheels, leading to a skid. It does this by reducing the amount of pressure sent to the rear brakes once a certain pressure threshold is met.
-
Metering: The metering valve delays the application of pressure to the front brakes, especially at the beginning of a braking event. This allows the rear brakes to engage slightly before the front brakes. This helps improve braking feel and reduce the tendency for the vehicle to "dive" forward during light braking. By allowing the rear brakes to engage first, it helps improve stability and prevents a sudden, jerky stop. It works by blocking pressure to the front brakes until a set pressure in the master cylinder is reached.
-
Pressure Warning: The combination valve includes a pressure differential switch that monitors the pressure balance between the front and rear brake circuits. If a pressure loss occurs in either circuit (due to a leak or failure), the switch activates a warning light on the dashboard, alerting the driver to a potential problem. This feature is crucial for safety, allowing drivers to identify and address brake system issues promptly.
In summary, the combination valve enhances braking performance, stability, and safety by managing brake pressure distribution and providing a warning system for brake failures.
