1995 ACURA TL lock

radiator cap bluetooth coolant temperature change time wipers wheel

Page 1294 of 1771

ACURA TL 1995 Service Repair Manual
Anti-lock Brake System (ABS)

Operation (cont'd)

Proportioning Control Valve Function:

The modulators for the rear brakes serve as proportioning

control valves to prevent the rear wheels from

Anti-lock Brake System (ABS)

Operation (cont'd)

Proportioning Control Valve Function:

The modulators for the rear brakes serve as proportioning

control valves to prevent the rear wheels from locking if

the ABS malfunctions or when the ABS is not activated.

When this function is not provided, the hydraulic pressure

from the master cylinder and the hydraulic pressure to

the rear brake system are equal.

If the fluid pressure is transmitted to the rear brakes at

the same rate as the front brakes, the rear wheels will

lock first because the rear axle load becomes lighter

when the brakes are applied.

To prevent the rear wheels from locking, the proportion-

ing control valve function changes the distribution rate

of the fluid pressure to the rear wheels when the pres-

sure in the rear brake system exceeds the given value of

the fluid pressure from the master cylinder. The fluid

pressure point where the distribution rate changes is

called the turning point.
FLUID PRESSURE WITHOUT PCV

FLUID PRESSURE WITH PCV

TURNING POINT

MASTER CYLINDER FLUID PRESSURE

The cut valve seat in the rear brake system has a shoulder between sections A and B. Section A, where pressure from the

master cylinder is applied, has a smaller diameter than section B, where pressure from the rear brake caliper is applied.

This design provides the proportioning control valve function as follows.

1. When the fluid pressure from the master cylinder is below the turning point, the cut valve seat is pushed by the

spring force and the cut valve is open. Therefore, the fluid pressure from the master cylinder is transmitted to the

rear brake caliper side. Under these conditions, fluid pressure from the master cylinder is equal to the pressure to the

rear brake caliper, but because of the diameter difference between sections A and B, the force on the cut valve over-

comes the spring force, moving the cut valve seat toward the cut valve slowly.

2. When the fluid pressure to the rear brake caliper reaches the turning point, the cut valve is closed by the cut valve

seat, blocking the fluid passage between the master cylinder side and rear wheel cylinder side.

3. When the fluid from the master cylinder exceeds the turning point, the fluid pressure from the master cylinder rises,

while the pressure to the rear brake caliper remains at the turning point value. As a result, the cut valve seat moves

away from the cut valve and the cut valve opens. The passage between the master cylinder and caliper opens

momentarily, but it is blocked again because the fluid pressure to the brake caliper rises, and the cut valve seat

moves to close the cut valve. As described above, when the pressure in the master cylinder is above the turning

point, the cut valve seat reduces the pressure in the rear brake caliper to the prescribed amount by repeating this pro-

cess.

From MASTER CYLINDER

To REAR BRAKE CALIPER

SPRING FORCE

SECTION WHERE PRESSURE FROM REAR CALIPER IS APPLIED.

SECTION WHERE PRESSURE FROM MASTER CYLINDER IS APPLIED.
CUT VALVE SEATProCarManuals.com