Isuzu KB P190. Manual - part 179

BRAKES  5C-17 

BRAKE LINES (HOSES AND PIPES) 
(MODEL WITH LOAD SENSING PROPORTIONING VALVE) 

N

⋅m(kgf⋅m/lb⋅ft)

 

 

 

 

 

RTW65CMF000501 

5C-18  BRAKES 

BRAKE LINES (HOSES AND PIPES) 
(MODEL WITH ABS) 

N

⋅m (kgf⋅m/lb⋅ft) 

 

 
 

 

 

This illustration is based on the RHD model

 

RTW75CLF000301 

 
 

BRAKES  5C-19 

SERVICING 

BLEND PROPORTIONING VALVE (IF SO EQUIPPED) 

 

 

 

 

 

 
 

Structure and Operation 

••••  Structure 
 

Side 

a

 shows P-valve; side 

b

 shows bypass valve. 

 

Bypass valve seals the routes 

4

 and 

5

 using the seal 

2

at 

the piston 

1

 end. 

 

In addition, spring 

3

 presses against the piston 

1

, and in 

order to seal out the route 

4

 and route 

5

 sufficiently, spring 

3

 presses seal 

2

 against cylinder end surface. 

 

The left figure is a characteristic curve diagram. 

 

5C-20  BRAKES 

 

 

••••  Operation 
 

The operation of the P-valve by the master cylinder 

pressure is unchanged up to the brake points 

A

 and 

B

. 

 

If master cylinder fluid pressure penetrates into the second

break point 

B

, the fluid pressure pressing against the seal 

, (which isolated route 

4

 and route 

5

), passing the route 

4

of the master cylinder side, overcomes the operating

force of the spring 

3

 + fluid pressure affecting the seal 

2

of 

the wheel cylinder, and presses the piston 

1

to the right 

side, resulting in the opening of the routes 

4

 and 

5

, and 

canceling of the P-valve operation. 

 

Then, because the master cylinder fluid pressure and the

wheel cylinder fluid pressure, up to the point 

C

, operate on 

the identical surface of the seal  , both have identical 

ascending ratios. 

 

However, because of the operation of spring 

3

in the wheel 

cylinder side, wheel cylinder fluid pressure operates to 

preserve the balance against the master cylinder fluid

pressure on the lower level with the difference in pressure 

resulting from this spring. 

 

 

 

 

RTW75CSH001601 

 

 

Valve Maintenance 

In the case of a fluid leak or other abnormality, the faulty valve 
should be replaced. 
The valve is set up at the engine room. 
Note: 
The blend proportioning valve is not repairable and must 
be replaced as a complete assembly.