Brake Tubes And Hoses; Junction Block; Proportioning Valve - Chrysler 2000 LHS Owner's Manual

5 - 4 BRAKES
DESCRIPTION AND OPERATION (Continued)
Fig. 4 Power Brake Booster Identification
1 – VACUUM CHECK VALVE
2 – MASTER CYLINDER PUSH ROD
3 – POWER BRAKE BOOSTER ASSEMBLY
4 – MASTER CYLINDER MOUNTING STUDS
5 – PART IDENTIFICATION TAG
As the brake pedal is pressed, the power brake
booster's input rod moves forward. This opens and
closes valves in the power brake booster, creating a
vacuum on one side of a diaphragm and allowing
atmospheric pressure to enter on the other. This dif-
ference in pressure forces the output rod of the power
booster out against the primary piston of the master
cylinder. As the pistons in the master cylinder move
forward this creates the hydraulic pressure in the
brake system.

BRAKE TUBES AND HOSES

DESCRIPTION
The chassis brake tubes are steel with a corrosion
resistant coating applied to the external surfaces.
The flex hoses are made of reinforced rubber.
All available brake systems on this vehicle use the
same type of brake line fittings and tubing flares.
The brake line fittings used are double-wall ISO style
tubing flares and fittings at all tubing joint locations.
Only the outlets of the proportioning valves and the
rear flex hoses threading into them have non-ISO
style flares. They are double-inverted style flares.
Refer to (Fig. 5) for specific joint locations and tube
fitting size.
OPERATION
The purpose of the chassis brake tubes and flex
hoses is to transfer the pressurized brake fluid devel-
oped by the master cylinder to the wheel brakes of
the vehicle. The flex hoses are made of rubber to
allow for the movement of the vehicle's steering and
suspension.

JUNCTION BLOCK

DESCRIPTION
A junction block is used on vehicles that are not
equipped with antilock brakes (ABS). The junction
block is located in front of the driver's side front tire
behind the front fascia. The junction block mounts in
the same location as the ABS integrated control unit
(ICU) does on vehicles with ABS.
It has six threaded ports to which the brake tubes
connect. Two are for the brake tubes coming from the
master cylinder. The remaining four are for the
brake tubes going to each brake assembly.
OPERATION
The junction block distributes the brake fluid com-
ing from the master cylinder primary and secondary
ports to the four brake tubes leading to the brakes.
Since the junction block mounts in the same location
as the ABS integrated control unit (ICU), it allows
for the common use of brake tubes on the vehicle
whether it is equipped with or without ABS.

PROPORTIONING VALVE

DESCRIPTION
Two in-line proportioning valves are used on both
the Antilock Brake System and all Non-Antilock
Brake applications (Fig. 6). One valve is used for
each rear brake hydraulic circuit.
The in-line proportioning valves are located in the
rear of the vehicle, at each rear brake flex hose. The
proportioning valves are not serviceable, but are a
replaceable component.
OPERATION
Proportioning valves balance front to rear braking
by controlling (at a given ratio) brake hydraulic pres-
sure to the rear brakes above a preset level (split
point). On light pedal applications equal brake pres-
sure is transmitted to both the front and rear brakes.
On heavier pedal applications, through the use of
proportioning valves, the pressure transmitted to the
rear will be lower than the front brakes. This pre-
vents premature rear wheel skid.
LH