Proportional valves exist in vehicles that have disc brakes in the front and drum brakes in the rear. Without the proportional valve, the disc brakes would be applied before the drum brakes because the pads in the discs are in contact with the discs, but the shoes in the drum brakes don't.
Nan prezans tiyo pwopòsyonèl, fren tanbou yo aplike anvan fren disk. Sa a ede kontwole frenaj ak estabilite.
Tiyo pwopòsyonèl pa pèmèt presyon rive nan fren yo disk jiskaske yo rive jwenn yon presyon predetèmine, ki se pi ba a presyon fren maksimòm, konsa pèmèt fren yo tanbou yo dwe aplike an premye.
Depi li mande mwens presyon pase fren devan an, li pèmèt mwens presyon rive nan fren an tanbou dèyè.