Impreza RS Coupe AWD F4-2.5L SOHC (1999)
Brake Proportioning/Combination Valve: Description and Operation
With ABS
Operation
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Operation before the split point
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Piston (1) is held by spring (4) so that valve (3) is kept away from valve seat (2). Under this condition, fluid pressure "P3" to rear wheel
cylinders equals fluid pressure "P2" from master cylinder.
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Operation near the split point
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Force "f1", applied to piston (1) by spring (4), is spring force "F". In other words, "f1" = "F".
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Force "f2" is also applied to piston (1) in the direction opposite to spring force "F" due to fluid pressure "P2" generated by master cylinder
according to cross sectional area "A".