"Gazelle" Gas-2705>> Brake system>> Maintenance service and repair of brake systems>> Repair of brake mechanisms of back wheels
Before performance of repair operations brake mechanisms should be washed carefully out warm water with washing-up liquids and are dried by compressed air.
For dismantling of the brake mechanism back колeca it is necessary:
- To execute operations on removal brake колодок (Replacement колодок brake mechanisms of back wheels »see«);

Fig. 8.16. Removal of a persistent ring

- To disconnect the pipeline from the wheel cylinder, to remove the wheel cylinder and to disassemble it. For this purpose it is necessary to remove at first rubber protective caps and пенополиуретановые rings. Then to turn a screw-driver pistons on 90 ° and to take out them from the cylinder. Needlessly it is not necessary to delete spring persistent rings. If for any reasons the ring is necessary for removing, are for this purpose applied special круглогубцы (fig. 8.16). Having entered round sponges (diameter of sponges of 4 mm and height of 5 mm) the tool in two special apertures on a ring to compress круглогубцы and to take out at first one, and then the second ring from the cylinder. To turn out the valve of prorolling of the wheel cylinder.
To wash out all details warm water with washing-up liquids and to dry a stream of compressed air, and then to inspect details of brake mechanisms.
The brake drum on a working surface should not have deep рисок and задиров. If necessary the drum should be chiseled in gathering with a nave concerning external rings of bearings. Palpation of a working surface of a drum should be no more than 0,2 mm. Not to lower durability of a drum, than 283,0+0,2 mm are not supposed расточка its internal diameter more.
At damage or especially deep risks, and also if necessary расточки till the diameter more it it is necessary for working surface of a drum to replace than 283 mm new.
Brake overlays are pasted by glue VS-JUT. Before gluing of a surface of a rim колодки and internal surfaces of an overlay it is necessary to smooth out and blow carefully compressed air. Put a uniform layer of glue and allow to it to dry out during 1 ч at temperature of an industrial premise. Then in the special adaptation of an overlay to press to колодкам with effort 500—800 кПа (5 8 kgs/sm 2). The adaptation to put in the furnace where to sustain at temperature 175—185 ° From not less than 30 mines without time of warming up of the furnace and колодок to the specified temperature, then to cool the adaptation together with the furnace to an ambient temperature during 3 ч, not less.
After приклейки the external surface of overlays is ground so that the radius was on 0,1—0,3 mm of less radius of a drum that accelerates to extra earnings колодок.
Колодки with overlays which have the big deterioration or are made oily in the course of work, it is necessary to replace new. It is supposed to use for the further operation колодки with partially greasy overlays. Thus overlays are necessary for washing out неэтилированным gasoline, to dry and clear a steel brush or a skin.
It is not necessary to replace only one of колодок brakes or колодки one brake mechanism. It is necessary to make replacement колодок on both brake mechanisms to exclude car withdrawal at braking.
It is necessary to check up, whether apertures of fastening of a board and wheel cylinders are broken. The board should not be will drive. Cracks on a board are not supposed.
The wheel cylinder and details entering into it to wash out in изопропиловом spirit or a pure brake liquid. A cylinder mirror to clear a pure napkin. The working surface should be absolutely smooth, without рисок and roughnesses. Defects to eliminate grinding in. If the piston of the wheel cylinder has teases, has become covered by corrosion which cannot be removed without infringement of the basic metal, or has unilateral deterioration, it is necessary to replace it new.
If sealing rubber rings of wheel cylinders have got out of the initial shape or have defects on a working surface, also it is necessary to replace them new.
Protective covers of wheel cylinders should be changed in the presence of the slightest damages, to which result tightness is broken. Moisture hit under protective covers leads to corrosion formation on a surface of the cylinder and on the piston that can cause jamming of the piston or premature deterioration of sealing rings.
Assemblage of brake mechanisms is made in an order, the return to dismantling. Thus it is necessary:
- Before assemblage of a detail of wheel cylinders to wash out in a soda solution, to blow compressed air and to ship in a fresh brake liquid;

Fig. 8.17. Position of persistent rings in cylinders

- To check up an arrangement of a cut of a persistent ring of automatic adjustment which should be in a vertical plane. Depth "And" (fig. 8.17) installations of a persistent ring in the wheel cylinder should correspond 11+0,5 mm;
- To watch, that at assemblage on sealing rings did not get mineral oil, kerosene and greasing. Rings should not be overwound.
After assemblage of brake mechanisms of back wheels it is necessary to add a brake liquid and to pump over system as it is specified above. The sizes of interfaced details and knots of brake system are resulted in tab. 8.2.

Table 8.2. The sizes of interfaced details and knots of brake system, mm