Chery QQ, Service Manual

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Importance of Proportioning Valve
1. Loads on front and rear wheels are different
The front wheels of the vehicle bear more of the vehicle weight than its rear wheels. In
addition, its center of gravity will move forward when in braking, resulting in increased
load on front wheels and reduced load on rear wheels. The bigger the braking force is, the
more obvious this change is.
2. The risk of too early locking of rear wheels
When in braking, the load on rear wheels is light, and this causes them to be easily locked
too early, thereby resulting in lateral sway of the vehicle body's rear half.
3. Measure to prevent the above problem from happening
Proportioning valve: to automatically reduce hydraulic pressures delivered from brake
master cylinder to rear-wheel brake wheel cylinders. Pressure reduction is in proportion to
the stepping force on the brake pedal.