Sidekick JX 2D 4WD L4-1.6L (1998)
Brake Proportioning/Combination Valve: Description and Operation
STRUCTURE OF P & DIFFERENTIAL VALVE
The P & Differential valve consists of a proportioning valve and differential switch.
PURPOSE AND OPERATION OF PROPORTIONING VALVE
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 breakpoint in the graph 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.
Its operation is as follows. Till the master cylinder side pressure (Pm) reaches breakpoint, 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
breakpoint, 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.
