Skoda Felicia

Since 1994 of release

Repair and car operation

The main brake cylinder (ГТЦ) with the valves-regulators of pressure built in in it

ГТЦ it is intended for creation of pressure of a working liquid in hydraulic contours of brake system of the car. The cylinder fastens by means of two nuts М10 on hairpins of the servo-driver of the vacuum amplifier.

ГТЦ from the case executed from pig-iron moulding in which the aperture of the cylinder in diameter of 22 mm in which pistons (3) and (10) drives of two contours of brake system are placed is pierced. In horizontal plane ГТЦ four apertures with a female thread are executed. Two left apertures with carving М6х1.5 are intended for вворачивания pressure valves-regulators in a contour of brake mechanisms of back wheels. The right apertures (М10х1.0) serve for connection of hydraulic lines of contours of forward brake mechanisms. In the top part of case GTTS (5) rubber sealing through passage plugs (5) and (12) nests under landing of tanks of a brake liquid are provided.

Back section ГТЦ is connected to brake mechanisms right forward and left back wheels (the first hydraulic contour). A lobby - to mechanisms left forward and right back wheels (the second contour).

In the piston (3) drives of the first brake contour are provided deepening under landing of a tip of a rod of a pusher of the vacuum amplifier of brakes.

Sealing cuffs (7) and (14) serve for hermetic sealing of working spaces of corresponding sections ГТЦ. The cuff (9) prevents penetration of a hydraulic liquid from one section in another, and a cuff (2) - hit in air cylinder.

Springs (8) and (15), established under pistons, provide reverse motion of the last. The spring (8), besides, Serves for increase in the effort put to the piston of the second section during braking.

Pins (4) and (11) limit return of pistons.

At squeezing of a pedal of a foot brake movement of a pusher of the servo-driver of the vacuum amplifier of brakes is transferred to the piston (3) ГТЦ and moves it in the cylinder. At displacement the piston compresses a spring (8) which, together with the increased pressure of a hydraulic liquid, displaces the piston (10). The cuffs planted on pistons (7) and (14) are thus displaced for limits of inlet apertures of tanks of a brake liquid. As a result, pressure increases in both hydraulic contours of system.

Pressure lifting in ГТЦ causes stronger pressing of sponges of sealing cuffs to walls of cylinders, in addition raising tightness of assemblage.

At release pedals pistons come back in a starting position under the influence of the efforts developed by springs. The inlet apertures informed with cavities of cylinders, open and the hydraulic liquid being in tanks freely gets to cylinders, automatically compensating increase the path volume, connected with deterioration of frictional overlays and-or leaks in lines.

In case of the damage of system causing depressurization of the first hydraulic contour, the piston (3) will move freely as pressure increase in a working cavity of the given section will stop. The piston (10) under the influence of the effort developed by a pusher of the vacuum amplifier and a spring (8), at the increased course of a pedal of a foot brake will provide serviceable functioning of the second hydraulic contour. In case of infringement of tightness of the second contour the piston (10) under the influence of the effort developed by a pusher and a spring (8), overcoming resistance of a spring (15), will move against the stop the core to a face wall of the cylinder. In the first brake contour there will be a normal increase pressure at the increased course of a brake pedal.

The valve-regulator () limits increase of pressure contours of brake mechanisms of back wheels, preventing premature blocking of the last. The valve case will screw in final aperture ГТЦ. Tightness of a joint is provided with a sealing lining (4). The transitive nozzle providing possibility of connection to assemblage of a brake line is screwed In a final aperture of the case of the valve-regulator. A brake liquid, arriving in an inlet aperture of a regulator, passes in a cavity between the rubber valve (3) and the Internal wall of the case. Further the liquid gets in the channel provided in the piston (7) and further, - to a brake line of a hydraulic contour of the brake mechanism of a corresponding back wheel. The spring (6) is picked up for effort of compression so that at pressure of a liquid to 20 kgs/sm ² remained on removal from the valve. At the further increase of pressure the spring is definitively compressed also the piston nestles on the valve which blocks through internally an aperture in it. As soon as pressure in front of the piston will exceed on sufficient size pressure behind the piston, last moves again, opening access of a liquid to a contour. Further the cycle repeats necessary quantity of times in the course of car braking.

Thanks to such functioning of valves-regulators pressure in supports brake mechanisms of forward wheels always remains not more low, than in wheel cylinders of mechanisms back that excludes possibility юза the last.

The valve-regulator of pressure located near to the back bridge

On models of release since December, 1995 one valve-regulator of pressure in contours of brake mechanisms of back wheels of the car is established. The design of the given regulator is similar that for the valves-regulators used on cars VW Golf.


The regulator corrects pressure in hydraulic contours of brake mechanisms of back wheels of the car depending on loading and body position.

During performance of procedures of routine maintenance of the car it is necessary to pay attention to tightness of connections of the valve-regulator and to check freedom of moving of components of its drive. In case of revealing of defects the regulator is subject to replacement in gathering. Check of serviceability of functioning of the valve-regulator should be made in the conditions of a car repair shop.

The tank of a brake liquid

The two-chamber tank of a brake liquid is executed from translucent plastic that allows to supervise visually liquid level in it. Connecting branch pipes of the tank are inserted into entrance nests ГТЦ equipped with sealing through passage plugs.

Inside the tank is divided by a partition on two independent chambers. The partition does not reach the top cover of the tank that allows to add a liquid at once in both chambers. Division of contours occurs only after lowering of level of a liquid below partition edge.

The jellied mouth of the tank is closed by a screw cover in which, along with system of channels of connection of an internal cavity with atmosphere, plugs of the gauge-switch of level of a brake liquid are built in and actually the gauge-switch (the Onboard electric equipment see the Head).

On the tank case there are labels of the minimum and maximum levels of a liquid.

The vacuum amplifier of brakes

The given device is intended for increase in the effort applied by the driver to a pedal of a foot brake for the purpose of increase of efficiency of braking.

The case of the block of the servo-driver of the vacuum amplifier consists of two parts: actually cases (5) and covers (1). Tightness of both parts of assemblage is provided with landing of edges of the diaphragm (3) clamped in a flute of the case. The diaphragm is tightly planted by the central part in a flute of the piston (2) and divides internal space of assemblage on two chambers. The spring (10) provides return of a rod (7) together with a diaphragm in a starting position.

The piston is mechanically connected to a rod of a pusher (7). On the rod end will screw an adjusting tip (8) with which help updating of an adjusting backlash between piston GTTS and a pusher (see Has undressed Removal, check of a condition and installation of the control valve of the vacuum amplifier of brakes from a hose) is made.

Tightness of landing of a pusher in assemblage is provided with a rubber lining (6).

In the assemblage piston the valve (12) against which the spherical end of an operating pusher (15) rests is placed. The pusher is connected about a pedal of a foot brake.

In a forward part of the valve (12) there is the saddle of the special form blocked, in turn, by the valve (13). The forward (vacuum) chamber (4) is connected by the channel (17) with the piston to the back (atmospheric) chamber (11) located behind the piston.

The filter (16), duplicating a role of a rubber protective cover (14), prevents hit of a dust in assemblage at засасывании atmospheric air.

At squeezing of a pedal of a foot brake the operating pusher moves the first valve of the piston which locks the channel connecting the vacuum chamber with atmospheric and opens access to last external air. Depression in the vacuum chamber at the working engine is created thanks to presence of connection with the inlet pipeline. Owing to difference of pressure from the different parties of the piston last is displaced to the left, compressing a spring and resting a pusher rod against piston GTTS.

At strong squeezing of a pedal of a foot brake the piston of the vacuum amplifier is displaced to the left on considerable distance. Thus the volume of the atmospheric chamber increases and in a cavity подсасывается external air a little.

After отпускания pedals the valve (4) provides alignment of pressure on either side of the piston, and the spring returns a diaphragm in an initial condition, causing also return displacement of a rod of a pusher and, accordingly, the first piston GTTS.

Depression giving the forward chamber of the servo-driver is carried out through the unilateral valve included in a line, connecting the block with the inlet pipeline of the engine. The valve prevents hit in the vacuum chamber of the servo-driver of air and fuel evaporations at the muffled engine. Thanks to this valve the first braking at the decayed engine occurs to working vacuum amplifier (after отпускания pedals the vacuum amplifier ceases to function).

As appears from the principle of functioning of the servo-driver resulted above the description, strengthening of brakes becomes possible only at the working engine when in the inlet pipeline of the last depression is supported.

For a stop towed or moving накатом at the decayed engine of the car it is necessary to put to a pedal of a foot brake a little большее, than habitual effort.

Spare parts to the servo-driver of the vacuum amplifier of brakes are not delivered, that is why, in default, the block is subject to replacement in gathering. The description of procedures of removal and installation of assemblage of the servo-driver is resulted in Section Check of serviceability of functioning, removal and installation of the vacuum amplifier of brakes. The landing sizes of the block are shown on an illustration.

Brake mechanisms of forward wheels

The basic components of the brake mechanism of a forward wheel are the brake disk and assemblage of a support with brake колодками.

The brake disk is cast from grey pig-iron and fastens to a flange of a nave of a wheel one bolt М6х14. The disk Inside is protected dirt hits by a special casing.

In the main case a support of the brake mechanism the piston is located. In анкерную скобу two are inserted equipped with frictional overlays Pads.

The support case fastens to анкерной скобе by means of one (mechanisms of original complete set Girgling) or two bolts (mechanisms of licence assemblage). In any case bolts are rolled in apertures in end faces of directing fingers. The case can is thus free move along directing fingers.

Directing fingers of a support are covered by a thin layer of silicone greasing and protected from dirt hit rubber dusterами. In анкерной скобе seats under installation brake колодок and two apertures in a carving under bolts with which help all assemblage fastens to a rotary fist ступичной wheel assemblages are equipped.

In the support case the hydraulic cylinder with the piston is concluded. Tightness of landing of the piston in the cylinder is provided with a sealing cuff.

Колодки consist of a metal plate on which the frictional overlay on the one hand is pasted. Колодка it is kept in a saddle by a spring fixed on a plate. In parallel the spring serves for elimination of vibrations Pads.

At squeezing of a pedal of a foot brake the hydraulic liquid influences the support piston, causing pressing колодок to a working surface of a disk. Piston moving lead to cuff deformation. After отпускания pedals pressure of a brake liquid falls and, thanks to spring properties of a cuff, the piston moves back, coming back in the cylinder. As a result of deterioration of cuffs there can come the moment when the piston after отпускания pedals ceases to be involved in the cylinder. Thus Pads remain pressed to a brake disk and the mechanism starts to overheat.

It is necessary to notice that in process of operation of frictional overlays колодок the piston gradually is more and more put forward from the cylinder. Thus the support case is displaced on directing fingers, automatically compensating deterioration.

Brake mechanisms of back wheels

The design of the drum-type brake mechanism of back wheels is presented on illustrations.

The stamped steel brake board fastens to the lever of a suspension bracket of a back wheel. To the bottom part of a board приклепаны arms of brake boots.

Boots have тавровое section and the top end rest against pushers of pistons of the wheel cylinder, and bottom - in the arm fixed on a brake board. On the convex party of boots special glue pastes frictional overlays.

Back boots of the right and left brake mechanisms have an identical design whereas lobbies are not interchangeable in view of presence in the bottom part of asymmetrically located axes under installation of clamps of automatic updating of working backlashes.

Boots are connected among themselves by two coupling springs - top and bottom. Springs have different length and provide прилегание the ends of boots both to pushers of pistons of the wheel cylinder, and to axes.

Through an aperture in the central part of boots it is passed анкерный a pin fixed шплинтом. The pin fixes a boot in axial напрвлении concerning a brake board.

The wheel cylinder) is cast from pig-iron. The cylinder a landing flange fastens on a board of the brake mechanism by means of two bolts М6х10. In a flange the aperture under the prorolling gate also is provided.

In the cylinder two pistons, equipped with rubber sealing cuffs are planted. The internal spring provides a constant clip of pushers of pistons to boots of the brake mechanism. Pushers of pistons have the special form and by the groove provided in an external end face are put on upper edges of boots. The wheel cylinder from both parties is protected rubber dusterами, preventing hit of pollution in assemblage.

The brake drum is cast from pig-iron. In a forward wall of a drum there are ten apertures (not including central). Two apertures are intended for drum fastening to a flange ступичной assemblages by means of bolts М8х16, four - for fastening to assemblage of the wheel disk, two more are auxiliary and are used at removal of a drum and remained two provide access for check of reverse motion of the lever of an automatic regulator of backlashes between boots and a drum.

At squeezing of a pedal of a foot brake the brake liquid being in the wheel cylinder forces to be moved apart assemblages of pistons, whose pushers move apart upper edges of boots, pressing the last frictional overlays to a working surface of a drum. After отпускания pedals boots come back in a starting position thanks to the effort developed by coupling springs.

The excessive size of a backlash between boots and a working surface of a drum conducts to increase in a free wheeling of a pedal of a foot brake and, accordingly to a delay of operation of brake mechanisms. In view of told, the mentioned backlash should be shown to a minimum. For this purpose brake mechanisms are equipped by the device of automatic updating of a backlash thanks to which the under control distance is constantly supported within 0.4 0.6 mm.

The razzhimnaja lath is a component of the mechanism of an automatic regulator of backlashes. Number of other components of the device concern established in the bottom part of a forward boot a clamp with a helicoid spring, and also a spring pulled between a lath and a special aperture in a back boot.

The backlash size between frictional overlays of boots and a working surface of a drum depends on backlash size between teeths on the bottom part of the adjusting lever and teeths on the top part of a clamp.