7.1.4. Shock-absorbers

Shock-absorbers are intended for clearing of the fluctuations of the car arising at movement along uneven roads. Their action is based on use of resistance to course of liquid through small sections through passage in valves of compression and return. Comfortableness of the car and durability of details of a body and the chassis substantially depends on operation of shock-absorbers. Normally working shock-absorbers have to extinguish fluctuations of the car after moving of an obstacle for 1 — 3 muscleman.

Fig. 6.11. Shock-absorber: 1 — a rod with an eye; 2 — a boot; 3 — a washer; 4 — a tank nut; 5 — an epiploon holder; 6 — a rod epiploon; 7 — a ring; 8 — a spring; 9 — a rod guide with the plug; 10 — the tank; 11 — the cylinder; 12, 16 and 22 — plates restrictive; 13 and 18 — plates; 14 — the piston; 15 and 21 — disks; 17 — a return valve nut; 19 — the compression valve case; 20 — a compression valve bolt; 23 — a compression valve nut




In a design of shock-absorbers (fig. 6.11) details of shock-absorbers of the Volga car GAZ-31029 are used. The principle of operation of these shock-absorbers is widely known and does not demand the detailed description. As working liquid in shock-absorbers the AZh-12T liquid (duplicating liquid — the HEY veretenny oil) in number of 0,265 l is applied.
Maintenance of shock-absorbers
During operation of any adjustment shock-absorbers do not demand. However, if the slowed-down clearing of fluctuations of cars after moving of an obstacle is revealed, then the shock-absorber needs to be checked. Industrially its characteristics are checked at the stand. If there is no stand, it is necessary to clamp the shock-absorber vertically for the lower eye and to pump over for the top eye not less than five times. At the serviceable shock-absorber the rod has to move evenly, without breakthroughs and vibrations at the appendix of constant loading to 300 N (30 kgfs). Movement time on length of the working course of stretching — no more than 15 pages.
If the shock-absorber is pumped over without resistance or, on the contrary, resistance is very big, it should be replaced or repaired.
In use the shock-absorber can have a dribble of oil through consolidation of a rod in the top part. For elimination of leakage it is enough to tighten a tank nut. When tightening the tightness of a rubber epiploon of the 6th rod at the same time increases. For tightening of a nut of the tank the shock-absorber needs to be fixed for the lower eye in a vice and to lift for the top eye a casing in extreme top situation.

Fig. 6.12. A special key for dismantling of shock-absorbers of release of 1997.




To tighten a nut a special key (fig. 6.12) the moment of 90 — 150 N · m (9 — 15 kgfs · м).
Removal and installation of the shock-absorber
Removal of the shock-absorber of a forward suspension bracket needs to be made in the following order:
- for simplification of access to the shock-absorber it is necessary to turn a wheel to capacity towards a forward part of a longeron;
- to turn off a nut of the lower finger of the shock-absorber, to remove a washer and the rubber plug;
- to turn off the same nut on the top finger, to remove also a washer and the rubber plug;
- to remove the shock-absorber from the car.
Installation of the shock-absorber is carried out in the return sequence.
Removal of the shock-absorber of a back suspension bracket is made similarly.
Repair of shock-absorbers
Dismantling of the shock-absorber should be made only in case of obvious malfunctions of the shock-absorber. Extent of dismantling depends on the nature of malfunction. So, if tightening of a nut of the tank did not exclude liquid dribble, then the shock-absorber needs to be disassembled partially.
To make dismantling of shock-absorbers in the following order:
- to clamp the lower eye in a vice, to put forward a rod 1 (see fig. 6.11) for the top eye up of refusal and to turn off a nut 4 tanks;
- to carefully shake for a rod 1 holder of the 5th epiploon 6 and to raise the cylinder 11 of the tank;
- holding the cylinder one hand and not taking out it from the tank, the copper hammer to beat out a guide of the 9th rod from the cylinder;
- to lower the cylinder on a bottom of the tank and, holding it, to take out a rod with the piston 14; to merge liquid from the tank and the cylinder in a volumetric glass;
- to take out the cylinder from the tank and, having clamped in a vice the compression valve case 19 for the lower part, to shake the cylinder and to exempt it from the valve case. As a rule, the valve of compression does not understand but only it is carefully washed out by kerosene and is pressed in the cylinder on the former place.
In need of its dismantling it is necessary to turn off a nut 23;
- to clamp in a vice a rod for the top eye and to turn off a nut of the 17th valve of return, to remove consistently a plate restrictive 16, disks 15, the piston 14, a plate 13, a spring and a plate restrictive 12.
    Before survey and the analysis of technical condition of details they need to be washed out in kerosene and to blow compressed air. Tightness of the shock-absorber depends on quality of surfaces of the interfaced details, consolidations and their sizes. At survey it is necessary to pay attention to the following:
- the rod of the shock-absorber needs replacement if on its working surface there are scratches, teases, corrosion or damage of the chromeplated layer;
- the epiploon of a rod should be replaced at wear or damage of ring combs on an internal working surface;
- the sealing ring 7 (see fig. 6.11) the tank is replaced if it is damaged when dismantling, is strongly deformed or shrank;
- the cylinder of the shock-absorber needs replacement if on its working surface there are teases or traces of corrosion. At the same time, as a rule, replace also the piston assembled;
- the plug of a guide of the 9th rod is subject to replacement if its internal diameter more than 16,05 mm and also if the surface of an opening of the plug has scratches or teases.
    Assembly of shock-absorbers at the disassembled valve of compression should be begun with assembly of the valve of compression in the following order:
- to fix a bolt of the 20th valve in a vice and to establish on it a spring, a plate 18, the valve case 19, throttle disks 21 and a restrictive plate 22. To tighten a nut the 23rd moment of 16 — 22 N · m (1,6 — 2,2 kgfs · м). To check existence of a provorachivaniye of a plate 18;
- to install the cylinder 11 on the case 19 of the valve of compression and easy blows of the copper hammer to besiege the cylinder before dense contact of its end face with the valve case.
Further it is necessary to start assembly of the shock-absorber in the following order:
- to fix in a vice for an eye a rod with a cover of a casing and to establish on it a nut 4 tanks, a washer 3 and a boot 2. Previously to apply a layer of TsIATIM-201 or Litol-24 lubricant on an internal surface of an epiploon of the 6th rod, to insert an epiploon into a holder 5 and to establish an epiploon with a holder on a rod together with a plate of an epiploon;
- in a guide of the 9th rod to install the plug, a spring 8, and to put on a sealing ring a pro-point of a guide 7 and to establish a subcollected guide 9 on a rod;
- to assemble on a rod the piston 14 with the return valve — to install a restrictive plate 12, a spring with a plate 13, the piston 14, disks 15, a plate 16 and a nut of the 17th valve of return. To tighten a nut the moment of 16 — 22 N · m (· l) and to raskernit 1,6 — 2,2 kgfs in two opposite places on a carving;
- to clamp the tank for an eye in a vice in vertical position, to lower the cylinder 11 with the return valve in the tank on a half of its height, to fill in a half of liquid in the cylinder, and the liquid rest — in the tank. To take out the cylinder from the tank and, supporting the cylinder over the tank, to check the expiration of liquid via the compression valve. At the correct assembly there has to be a drop expiration of liquid;
- to insert without distortion a rod with the piston 14 into the cylinder, to install a guide of the 9th rod in the cylinder and slowly that there was no liquid splash, to lower the cylinder in the tank;
- to wrap a nut the 4th moment of 70 — 90 N · m (7 — 9 kgfs · l) at the put-forward rod. At a nut inhaling the guide of a rod will be pressed in the cylinder.
After assembly of the shock-absorber it is necessary to push-put forward several times a rod before emergence of uniform effort on all length of its course. For check of tightness of the shock-absorber it is recommended to sustain after assembly it in horizontal position with the rod pushed to the full not less than 10 hours.
The sizes of the interfaced details of shock-absorbers are specified in tab. 6.1.

Table 6.1. The sizes of the interfaced details of shock-absorbers, mm