Hydraulic shock absorbers

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Hydraulic shock absorbers installed on the VAZ-2101, VAZ-2102 and VAZ-2103 models are unified and interchangeable.

Front and rear shock absorbers differ in bottom and top mounts, operating diagram, rod travel and some details described below. Shock absorbers of telescopic type, double-acting.


Operating fluid used for filling shock absorbers, MGP-10 according to TU 38-1-01-137-71.

Shock absorber filling capacity, l:

• anterior — 0.1 20±0.005;
• posterior — 0.195±0.005.

The front shock absorber consists of the following main units: a rod assembly with a piston, valves, a guide sleeve with seals, a reservoir nut and a casing; working cylinder; tank assembly with an eyelet; compression valve.

The reservoir 13 of the shock absorber is made of steel electrowelded pipe. An eyelet 1 is inserted and welded into the calibrated belt of the lower end of the coarse. The upper end of the tank has an internal thread for fixing the nut 15. The housing 32 of the compression valve is inserted into the recess of the bottom of the eyelet 1.

The valve body has a central stepped hole with a thread in the upper part and eight holes D evenly spaced around the circumference of the undercut for discharging liquid into the cylinder. A seat 29 is screwed into the valve body together with a compression valve 4, which is loosely inserted into the central hole of the seat. The valve is pressed with a cone to the chamfer of the seat opening, creating the necessary tightness.

To bypass liquid during a sharp piston stroke, the compression valve has a central channel with an exit through a side rectangular hole into an annular slot formed by the conical surfaces of the seat and valve.

A calibrated hole is provided in the head of the compression valve for throttling the liquid with a quiet piston stroke. From below the valve is pressed by a spring 2.


The valve seat with a hex head presses the restrictive plate 30 of the intake valve, the conical spring 31 and the intake valve 3.

The inlet valve 3 is a washer with a central shaped hole for centering on the shoulder of the restrictive plate 30.

The working cylinder 12 is pressed onto the landing belt of the compression valve body 32; the inner surface of the cylinder is calibrated. Inside the cylinder, a ceramic-metal piston 28 is installed on the rod 17. The piston has four bypass channels d evenly spaced in a concentric groove and four underwater holes b, evenly spaced in a concentric groove of a smaller diameter. A groove is made on the outer surface of the piston, into which a ceramic-metal piston ring 7 is inserted to seal the gap between the piston and the cylinder.

The position of the piston on the rod is fixed by the restrictive plate 10 of the bypass valve and the nut 5 of the recoil valve. The tightening torque of the nut on the rod is 1-1.5 kgf·m.

During assembly, before installing the restrictive plate and piston, a polyurethane buffer 11 is installed on the rod, which softens the impact of the restrictive plate on the guide sleeve during recoil.

A bypass valve 9 and a twisted conical spring 25 pressing it are placed between the restrictive plate and the piston. The bypass valve closes the channels r of the piston from above.

Holes b from below are blocked by a recoil valve, consisting of a package of discs 26, 27 and washer 33. Disc 26 is called a throttle. Two opposite cutouts are made along the outer edge of the disc, through which the operating fluid is throttled at a low piston speed. The inner edge of the recoil valve is rigidly pressed against the piston by nut 5, and the outer edge is pressed against the piston by a copper-plated spring 6 through thrust plate 8. Washer 33 stabilizes the operation of the valve and protects the lower disk from damage by the nut.


The shock absorber rod 17 perceives axial loads arising from vibrations of the body and suspension, and moves the piston along the working cylinder. The friction surface of the rod on the guide sleeve 23 and gland 21 (along the length of the largest diameter) hardened to high hardness, polished, plated with chrome and then polished again. High surface finish is essential to maintain a good stem seal; chrome plating of the stem increases the wear resistance of its surface.

To guide the rod relative to the working cylinder, a ceramic-metal bushing 23 is used, in which, in addition to the central one, two inclined holes are made: one (V) a capillary step for removing air from the working cylinder, the other for installing a polyethylene drain tube 24. An oil seal 21 made of petrol-resistant rubber is installed with a slight tightness on top of the shoulder of the guide bush 23.

The guide sleeve 23 is freely installed in the calibrated seat belt of the upper end of the tank 13. The upper end of the working cylinder is pressed onto the lower outer recess of the sleeve 23. The junction of the tank 13 with the guide sleeve 23 is sealed with a rubber ring 22, pressed from above by the clip 20 of the stuffing box. Between the gland cage and the nut (lid) tank 13, a rubber gasket 19 and a ceramic-metal protective ring 18 are installed, which removes abrasive particles (dirt) from the rod during the compression stroke.

The compression valve body, the working cylinder with a guide sleeve, the sealing ring, the stuffing box 20, the gasket 19 and the protective ring 18 are clamped by the nut 15 screwed into the upper end of the tank 13. Four holes are made in it to tighten the nut 15 with a special wrench. Tightening torque of the nut 15 7-9 kgf·m.


On the upper end of the rod 17, a cover with a casing 14 welded to it and a bushing 16* of the upper shock absorber hinge are pressed into the shoulders until it stops. A rubber-metal hinge is pressed into the eye 1 of the shock absorber.

The design of the rear shock absorber differs slightly from the design of the front shock absorber: the shock absorber rod does not have an upper threaded end; the mounting lug 35 is directly butt-welded to the stem 34; throttle disc 26 instead of two, the front shock absorber disc has six cutouts; the working cylinder is longer, since the piston stroke of the rear shock absorber is greater than the front one, the reservoir and drain pipe are correspondingly longer; spring 6 of the recoil valve is softer in characteristics than the similar spring of the front shock absorber and, unlike it, is not copper-plated.

The buffer 11 of the recoil stroke on the rod 34 of the rear shock absorber is not installed.

shock absorber work. The working cylinder with the piston and the tank body form three cavities in the shock absorber: the upper (in the working cylinder above the piston), must be constantly filled with operating fluid; lower (in the working cylinder under the piston), constantly filled with operating fluid; the cavity between the working cylinder and the tank body contains a reserve amount of operating fluid and air.

compression stroke. Under the influence of compressive forces, the piston moves down. The liquid under the piston lifts the bypass valve 9 and flows through the channels d into the upper cavity. Part of the liquid, equal in volume to the retractable rod, flows through the compression valve 4 into the reservoir. At a low piston speed, there is not enough pressure to overcome the resistance of spring 2 and the liquid is throttled through hole a of the compression valve. At a high piston speed, the liquid does not have time to flow through the throttle hole. The pressure in the working cylinder rises, which opens the compression valve and releases fluid into the reservoir, relieving excess pressure.

During the compression stroke, only the throttling through the compression valve of the liquid volume equal to the volume of the inserted rod has a damping effect.

The flow of liquid through the bypass holes of the piston has almost no braking effect.

Recoil move. When the shock absorber is stretched, the piston begins to move upward and exerts pressure on the liquid in the upper cavity. Bypass valve 9 closes. Liquid begins to flow from the upper cavity to the lower one.

At a low piston speed, the fluid supplied through the figured cutouts (by inner diameter) bypass valve 9 and holes b of the piston are throttled through constantly open throttle slots formed by cutouts on the throttle disc 26, thereby creating rebound resistance.

At a high piston speed, the fluid pressure increases so much that the recoil valve discs bend and the main fluid flow flows through the formed annular gap between the throttle disc and the piston, relieving excess pressure.

The volume of liquid in the upper cavity of the working cylinder is less than the volume of liquid in the lower cavity by the value of the volume of the rod leaving the cylinder. Therefore, the missing volume of liquid enters the lower cavity under the suction action of the piston and the air pressure in the reservoir through the holes d, overcoming the resistance of the spring 31 and opening the inlet valve 3.

The resistance of the recoil stroke is several times greater than the resistance of the compression stroke and is achieved by selecting the appropriate structural elements of the shock absorbers. This is necessary to reduce the impact of shocks on the car body that occur when the wheel hits a road obstacle.

When the car is parked, air and fluid vapors accumulate in the shock absorber cylinder. To remove them from the cylinder in order to speed up the inclusion of the shock absorber in operation, a capillary hole in the guide sleeve and a drain tube 24 serve.