3.12 Brake System

The load-related brake proportioning valve is conceived for adjusting the brake pressure at the rear axle to the respective load condition and is controlled according to the spring suspension at the rear axle.

The load-related brake proportioning valve is provided ex-works with a regulation, based on a tension spring, relating to the unladen weight of the vehicle. Usually, it is not required to re-adjust this regulation - not even after mounting an attachment onto the chassis.

In special cases - for example retrofitting of reinforced springs, mounting of an unusually lightweight attachment - it is required to correct the regulation of the brake proportioning valve. The pressure check and regulation should be carried out at a Volkswagen dealer/workshop for utility vehicles. The regulation has to be performed in such a way that the balance beam is horizontal.

Check:

Inlet pressure on front axle wheel cylinder bleeder valva

Mean value from left and right

Test:

Outlet pressure on rear axle wheel cylinder bleeder valva

Rear axle load (kg)

Input pressure (bar)

Output
pressure (bar)

500
600
650
700
750
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800

50
50
50
50
50
50
100
100
100
100
100
120
120
140
140
140

14±2
14±2
15±4
19±5/2
24±6/4
29±6/4
45±6/4
53±8
62±8
69±10
75±2
82±10
87±10
97±122
103±129
108±135