9.1. General information

The working brake system with a hydraulic drive consists of two independent contours divided on a diagonals (the left forward — right back, right forward — left back wheels). Forward brake mechanisms with ventilated disks, back — drum-type.

Into structure of a hydraulic drive of working brake system enter the main brake cylinder with regulators of pressure of back brakes, the vacuum amplifier and, depending on updating, anti-blocking system (ABS).

In the presence of ABS disk back brake mechanisms are used. Pressure regulators on cars with ABS are established on a beam of a back suspension bracket.

On cars with the diesel engine the structure of brake system also includes the vacuum pump.

Fig. 7.1. Brake mechanism of forward wheels of the CL22VD and CL22VE types: 1 — directing fingers; 5 — a protective cover; 3 — directing brake shoes; 4 — a brake disk; 5 — clamping the loose leaf of blocks; 6 — a brake shoe; 7 — clamping springs; 8 — shumogasyashchy laying; 9 — a bolt of fastening of a finger; 10 — the union for pumping; 11 — a support; 12 — a sealing ring; 13 — the piston; 14 — an antisplash cuff.

Brake mechanisms of forward wheels — with a floating bracket, one-piston, with pig-iron ventilated disks (fig. 7.1).

Characteristics of the forward brake mechanism are specified in tab. 7.1.

Characteristic	GA14DE engine	Engines GA16DE, CD20
Type	CL22VD	CL22VE
Diameter of the piston of the wheel cylinder, mm	54
External diameter of a brake disk, mm	232	247
Thickness of a disk, mm:
the nominal	18
the minimum admissible	16
Axial palpation of a working surface of a disk, no more, than a mm	0,07
Unevenness of thickness of a disk, no more, than a mm	0,02
Length/width of brake shoes, mm	106/39,5
Thickness of frictional slips, mm:
the nominal	11
the minimum admissible	2
Brand of frictional slips	Akebono AP55HFF

Fig. 7.2. Drum-type brake mechanism of a back wheel of the LT18C type: 1 — a dustproof cuff; 2 — the piston; 3 — a cuff; 4 — the brake cylinder; 5 — the union for pumping; 6 — a spring; 7 — a cable of the parking brake; 8, 12, 13 — a basic rack of a block with a spring and a cup; 9 — a brake board; 10 — squeezing the lever; 11 — a squeezing brake shoe; 14 — the bottom coupling spring of blocks; 15 — a spring of the mechanism of automatic adjustment of a gap; 16 — a brake drum; 17 — a clamping brake shoe; 18 — the mechanism of automatic adjustment of a gap; 19 — the top coupling spring of blocks

Brake mechanisms of back wheels drum-type, the LT18C type, with the mechanism of automatic adjustment of a gap and the built-in drive of the parking brake. Internal diameter of the brake cylinder of 15,87 mm, internal diameter of a drum of 180 mm, maximum permissible after boring of 181 mm; ovality of a drum no more than 0,03 mm. Length of frictional overlays of 172 mm, width of 30 mm. Thickness of frictional overlays of Akebono A90TEE brand of 4 mm, minimum admissible — 1,5 mm. The device of the drum-type brake mechanism is shown on fig. 7.2.

Fig. 7.3. Disk brake mechanism of back wheels of the CL7HB type: 1 — the lever of a drive of the parking brake; 2 — a sealing ring; 3 — a lock ring; 4 — struts; 5 — a shaped washer; 6 — the bearing; 7 — a piston rod; 8 — the piston; 9 — a dustproof cuff; 10 — a sealing ring; 11 — a rod; 12 — a persistent washer of a spring; 13 — a spring; 14 — a clamping spring; 15 — clamping laying of blocks; 16 — bolts of fastening of directing fingers; 17 — directing fingers of brake shoes; 18 — protective covers of fingers; 19 — directing brake shoes; 20 — a brake disk; 21 — antinoise laying; 22 — a brake shoe

On cars with ABS disk back brake mechanisms of the CL7HB type, one-piston, with a floating bracket (fig. 7.3) are established. Diameter of the piston of the wheel cylinder of 30,23 mm. External diameter of a brake disk of 234 mm. Nominal thickness of a disk

7 mm, minimum admissible 6 mm. Length of brake shoes of 94 mm, width of 29 mm. Thickness of frictional overlays of 10 mm, minimum admissible at wear of 1,5 mm. Brand of frictional overlays of Akebono AP52FF.

The main brake cylinder has two consistently working pistons and two built-in regulators of pressure of back brakes (option without ABS).

Internal diameter of the cylinder, mm:

without       ABS 20,64

with       ABS 22,22

Brake pressure of forward/back brakes, MPa:

without       ABS 6,5/3,5 — 3,9

with       ABS 7,5/5,2 — 5,6

Vacuum amplifier of the H195T brand of double action.

Diameter of a diaphragm of primary contour of 205 mm, secondary contour of 180 mm.

Distance from a body floor to a pedal (in a free condition at the appendix of effort of 490 — 500 N):

cars with a mechanical transmission — not less than 148 — 158/75 mm;

cars with an automatic transmission — not less than 157 — 167/85 mm.

Fig. 7.4. Details of system of the vacuum amplifier of models with the diesel engine: And — the CD20 engine; B — the CD20E engine (was issued since April, 1996): 1 — the generator; 2 — sealing rings; 3 — a rotor; 4 — blades; 5 — the case of the vacuum pump; 6 — a vacuum hose; 7 — the switch; 8 — clamps of hoses; 9 — a cover; 10 — the vacuum pump; 11 — a drain oil pipeline; 12 — the depression accumulator; 13 — a bringing oil pipeline

The vacuum pump on diesel CD20 engines is established behind on a generator shaft. On diesel CD20E engines the vacuum pump is established on a head of the block of cylinders and brought from a camshaft. Details of system of the vacuum amplifier are represented on fig. 7.4.

The system of the parking brake hummock hand-operated, affects brake mechanisms of back wheels. The drive lever at the appendix of effort of 200 N should move on 7 — 8 teeths of the ratchet mechanism.

The anti-blocking system of brakes of the Nippon Denso brand with the electronic control unit can be established on all models of cars.

Into structure of ABS enter:

— the electronic control unit which has been built in the hydrounit, located in a forward part of a motor compartment at the left. The electronic control unit (EBU) regulates by means of electromagnetic valves pressure in brake mechanisms, preventing blocking of wheels. Emergence of a tendency to blocking of one or several wheels is defined by sensors of speed of rotation of lobbies and back wheels. Also EBU receives information on pressing a brake pedal from the stoplight switch;

— four induction sensors of speed of rotation of lobbies and back wheels;

— the relay of management and protection against power surges in an onboard network;

— a control lamp of malfunction of the system, located in a combination of devices.

Fig. 7.18. Bolt of fastening of the sensor of speed of rotation of a forward wheel: 1 — a place for check of a gap of the sensor

Fig. 7.22. Check of a gap of the sensor of speed of rotation of a back wheel

— sensors of speed of rotation of lobbies and back wheels of inductive type, are established on rotary fists of forward wheels and on an axis of a back nave opposite to gear rotors. Resistance of sensors of 800 — 1200 Ohm. The air gap (see fig. 7.18, 7.22) makes 0,1 — 1,1 mm and is not subject to adjustment;

— the hydrounit is located about the top fastening of the right forward rack of a suspension bracket. It consists of eight electromagnetic regulating valves, the electropump and the relay of inclusion of power supply, the relays established on the block.