Sidekick JSS 4D Hard Top 2WD L4-1.8L (1997)
Brake Fluid Pressure Sensor/Switch: Description and Operation
NOTE: The Proportioning & Differential (P & D) Valve consists of a proportioning valve and differential switch.
REGULATING FLUID PRESSURE
The proportioning valve regulates the brake fluid pressure in the rear brake line, which is the same both on the master cylinder side and wheel cylinder
side up to the break-point in the graph (F/S) but once the fluid pressure on the master cylinder side exceeds that point, that on the wheel cylinder side
increases as shown by the graph.
OPERATION
Till the master cylinder side pressure (Pm) reaches (F/S), the spring force (F) is higher than the force caused pressure (F = Pm*S) and so Pm is
transmitted to the wheel cylinder side as it is through the opening between the plunger and cup. As Pm rises higher than (F/S), F. exceeds F and the
plunger moves to the right as shown in the figure to close the above opening.
When Pm rises even higher, the plunger moves to allow the opening. Then the wheel cylinder side pressure (Pw) increases and the opening is closed.
Such operation cycle is repeated and Pm is transmitted to the wheel cylinder as Pw as shown by the above graph.
