Elastic suspension elements. Most common leaf springs. They are easy to make and repair. They do not need, unlike spring and torsion springs, lever guides.

There are three types of leaf springs (Fig. 22.2, U): semi-elliptical (a), cantilever (b) and quarter (c).

The shape of the sheet set corresponds to the bending moment diagram, i.e. the spring is a beam equal resistance.

The mounting of the springs of the first two types is asymmetric, which provides resistance to roll and "peck" when braking. Coefficient

Rice. 22.2.

/ - leaf springs: a- semi-elliptical; b- cantilever; in- quarter; II- pneumatic elements: a- two-section; b, c- diaphragm;

G- sleeve asymmetry z = (1 2 - 1 () / 1\u003d 0.1-0.3 - The deformation coefficient of the semi-elliptical spring 5 \u003d 1.45-1.25.

The leaf spring consists of a root sheet, which is connected to the frame, and other sheets pulled to it by clamps. Before assembly, the sheets have different curvature. Longitudinal displacement of sheets is limited by protrusions that enter the recess of the adjacent sheet, or the central tie bolt. To reduce friction, a layer of graphite lubricant is applied to the sheets or non-metallic gaskets are placed between them. The cross section of the springs is rectangular, T-shaped or trapezoidal. The spring is attached to the bridge with stepladders with overlays, one end of the root sheet is hingedly attached to the body, and the other - through an earring. Also used are the fastening of the ends of the springs on rubber cushions. This fastening does not require lubrication and reduces the twisting of the spring when the frame is distorted.

coil springs(springs) are more often used with independent wheel suspension. Cylindrical springs are linear, while conical springs are progressive.

torsion bars are a shaft or a bundle of shafts that twist during the impact of the road on the suspension. They are used for independent wheel suspension of multi-axle vehicles, trailers and small cars. The energy of elastic deformation of torsion bars is 2-3 times greater than that of leaf springs.

elastic pneumatic elements often used on vehicles with variable sprung weight (buses, container ships, trailers, etc.). The characteristic of the air suspension is non-linear, its parameters can be changed by changing the air pressure. High running smoothness can be obtained with relatively small displacements of the masses of the body and the unsprung part. By changing the air pressure, you can adjust the position of the body relative to the road, and with independent suspension - ground clearance.

Balloon and diaphragm elastic elements (Fig. 22.2, II) made of two-layer rubber-cord casings. Capron or nylon is used for the cord, for the outer layer of the cylinder - oil-petrol resistant rubber, and for the inner layer - rubber. For cylinders (Fig. 22.2, //, a) characterized by high tightness. However, to work with them on low-frequency vibrations, additional tanks are used. Using diaphragm and sleeve elements (Fig. 22.2, //, b, c, d) you can get a low natural frequency of the suspension. These elements require less air to operate. However, due to the friction of their shell against the piston, they wear out faster.

Hydropneumatic telescopic type elements transmit pressure to the gas cushion through the liquid. These devices are more compact than pneumatic ones, as they operate at pressures up to 20 MPa.

Guide devices are determined by the suspension scheme. At dependent suspension (Fig. 22.3, a) both wheels are rigidly connected to the axle beam. When you change the position of one of the wheels in height, the angle changes x. In this case, when the wheel rotates, a gyroscopic effect occurs, tending to return the axle to its previous position, which leads to tire and axle wear. At independent suspension (Fig. 22.3, b-e) each wheel is sprung separately. With a single-lever suspension (see Fig. 22.3, b) the system also has a gyroscopic effect. At double wishbone suspension parallelogram (see Fig. 22.3, in) and trapezoidal with levers of different lengths (see Fig. 22.3, G) there is no angular movement of the wheel, but there is a lateral displacement D/, which leads to lateral wear of the wheels.

On the cars widely used lever-telescopic suspension "swinging candle" ("MacPherson candle", see Fig.

Rice. 22.3.

a- dependent; b- independent single-lever; vig - independent double-lever with levers of equal and different lengths; d- independent lever-telescopic fig. 22.3, d). It provides a slight change in track and camber, has a low mass, a large distance between the supports of the right and left wheels, and a large stroke in height.

Balancing suspensions (Fig. 22.4) are used on multi-axle vehicles. Pendants with a short balancer (Fig. 22.4, a) used on semi-trailers and vehicles with a 6x2 wheel arrangement. In the suspension shown in Fig. 22.4, b, a large balancer is installed under the leaf spring, and above it - jet thrust(in MAZ vehicles). In the diagram in fig. 22.4, in the spring itself is a balancer, and jet rods are installed above and below, limiting the movement of bridges (ZIL, KrAZ, UralAZ vehicles).

Rice. 22.4. Schemes of balancing suspensions: a- four-spring with a balancer; b- two-spring with a rigid balancing beam; in- with balance springs and jet rods

Stabilizers. When turning the vehicle under the action centrifugal force the body tilts, the position of the center of mass changes, which can lead to a rollover of the machine. To prevent this phenomenon, the suspension must have angular rigidity in the transverse direction, which is achieved by installing stabilizers. Often the stabilizer is a torsion bar, which twists when the body is tilted. On passenger cars, the stabilizer is installed on front axle and rarely in the back. Sometimes the function of the stabilizer is performed in the rear suspension by a U-shaped beam rear axle(VAZ cars).

Vehicle suspensions are classified according to the design (or types) of guide devices and elastic elements. The guiding devices are used to perceive and transfer the traction, braking and lateral forces that occur when turning from the wheels to the body. The design of the guide device affects the nature of the change in the position of the body and wheels of the car when driving. The elastic elements in the suspension are the main converters of dynamic loads transmitted through the wheels from the road to the body. The greatest effect of reducing dynamic loads is possessed by "soft" suspensions, which have elastic elements with low rigidity. Such suspensions can provide low vibration frequencies of the body (no more than 1 Hz), creating greatest comfort when the car is moving, as they allow isolating the body from the effects of forces arising from the interaction of the wheels with road irregularities.

It is believed that for passenger cars the best comfort (lack of driver fatigue during a long drive and no sensation of body vibrations when driving on a paved road at various speeds) is achieved if the acceleration of the body does not exceed 0.5-1 m / s 2 with vertical own body vibrations at frequencies up to 1 Hz.

The guiding device of the suspension determines the kinematics of the wheels in relation to the body and the road, which has a significant impact on the performance of the vehicle. Abstracting from some design features of the used guide devices, they can be represented as simple circuits (Fig. 2) .

The guiding device is a set of levers various designs, rods and hinges that connect the wheel to the body and ensure the transmission of forces and moments. To transfer axial forces, as a rule, simple rods with hinged supports, which exclude bending loads, are used. An example of such rods is the longitudinal suspension rods of the driving wheels of VAZ-2101 cars; -2107, Mazda RX7, Volkswagen, Daimler-Benz and transverse, for example, Panhard rod, which perceives transverse forces in dependent suspensions. The cross-sectional profile of such rods can be different, but providing high resistance to buckling. Greatest Application found rods of round section.

AT independent suspensions where transmission of forces in transverse and longitudinal directions is required, triangular or crescent-shaped levers are used that are resistant to longitudinal forces and have bending strength from longitudinal and transverse loads. The levers are made by stamping or forging from steel or aluminum alloys. In some cases, casting and welded structures are used. The transverse levers of Porsche, Daimler-Benz and other cars are made of aluminum alloy.

Suspension guide arms are connected to the wheel and body using ball joints and bushings. Hinges can be guides and carriers. For example, in an independent wishbone suspension, a resilient element rests on the lower arm. The ball joint of such a lever perceives forces acting in different directions, therefore, the hinge must be load-bearing. The hinge on the upper arms does not perceive vertical forces, but transmits mainly transverse ones. In this case, a guide hinge is used. On fig. 3 showing carriers ball joints and guide joint used on automobiles. It should be noted that similar hinges are also used on steering rods. The joints have a cylindrical or tapered (1:10) guide shank, the ball head is covered with a plastic (acetyl resin) insert, protective case is filled special grease. Such hinges (manufacturers Ehrenreich, Lemförder Metalvaren) have good tightness against dirt and practically do not require maintenance.

Bearing hinge draws attention (Fig. 3b) , having additional sound insulation in the form of elastic rubber liners, used by Daimler-Benz to isolate rolling noise from radial tires.

The supporting nodes of the suspension guide should have low friction, be sufficiently rigid and have sound-absorbing properties. To meet these requirements, rubber or plastic inserts are introduced into the design of the supporting elements. As the materials of the liners, tact is used that does not require maintenance during operation, for example, polyurethane, polyamide, teflon, etc. The use of rubber liners in the bushings provides good sound insulation, torsion elasticity and elastic displacement under load.

Silent blocks are the most widely used in supporting elements. (Fig. 4) , consisting of a rubber cylindrical bushing, pressed with a large compression between the outer and inner metal bushings. These bushings allow twist angles of ±15° and misalignment up to 8° (Fig. 4a) . Sleeve (Fig. 4b) used on the BMB-528i car, made by vulcanizing rubber between two steel bushings, has good noise-absorbing properties and sufficient rigidity. Sleeve (Fig. 4c) has found wide application in transverse rods and shock absorbers.

On the wishbones of Daimler-Benz 280S / 500SEC and Volkswagen cars, so-called sliding bearings are installed, in which the intermediate bushing can slide along the inner one, providing low torsional rigidity (deformation does not exceed 0.5 mm with a lateral force of 5 kN). The support is lubricated, and the moving part is sealed with mechanical seals.

To ensure the absorption of such noise on BMW 5-series cars, rubber mounts are used, which are pressed into the cross member. rear suspension on both sides and having different stiffness depending on the direction of deformation. The front suspension of the Honda Prelude and Ford Fiesta cars uses a combined bushing made of polyurethane, plastic and steel washers, which provide different stiffness characteristics depending on the direction of the forces. On front-wheel drive cars "Audi-100/200" and "Opel Corsa" a one-piece curly rubber bushing is used in the transverse levers, which, depending on the direction of the rolling resistance forces, has different rigidity with the necessary elasticity in the lateral and vertical directions.

Elastic suspension elements are distinguished by the design and material from which they are made. The main characteristic of an elastic element is stiffness (the ratio of the load to the deformation or deflection that it causes), i.e. elastic resistance of the material various types loads.

Metals, rubber, some plastics and gases have this property to the greatest extent. best view The elastic characteristic is a progressive characteristic that has a certain rigidity in the middle part (the zone of body oscillations that provide the greatest comfort when driving the car) and high rigidity in the extreme positions of the suspension guide during compression and rebound to prevent hard impact.

Therefore, suspensions use a combination of elastic elements, each of which performs its specific function. As a rule, the composition of the elastic elements includes: the main elastic elements that perceive the vertical load created by the mass of the car; additional elastic elements that provide an increase in the rigidity of the main elastic element and limit the suspension travel, excluding a hard impact; a stabilizer that provides an increase in the rigidity of the main elastic element during transverse-angular vibrations and body tilts when turning the car. Metal elastic elements have a linear elastic characteristic and are made of special steels with high strength at large deformations. Such elastic elements include leaf springs, torsion bars and springs. Leaf springs are practically not used on modern passenger cars, with the exception of some models of multi-purpose vehicles. It can be noted the models of passenger cars that were previously produced with leaf springs in the suspension, which continue to be used at the present time. Longitudinal leaf springs were installed mainly in the dependent wheel suspension and served as an elastic and guiding device. Both multi-leaf and single-leaf springs were used.

Springs as elastic elements are used in the suspension of many cars. In the front and rear suspensions, manufactured by various companies in most passenger cars, helical coil springs with a constant bar section and winding pitch are used. Such a spring has a linear elastic characteristic, and the necessary progressiveness is provided by additional elastic elements made of polyurethane elastomer and rubber rebound buffers. On a number of vehicles, a combination of coil and shaped springs with variable bar thickness is used to provide progressive performance.

Shaped springs have a progressive elastic characteristic and are called "mini-blocks" for their small height. Such shaped springs are used, for example, in the rear suspension of Volkswagen, Audi, Opel, etc. Shaped springs have different diameters in the middle part of the spring and along the edges, and miniblock springs also have a different winding pitch. On BMW 3 series cars, a barrel-shaped spring with a progressive characteristic is installed in the rear suspension, achieved due to the shape of the spring and the use of a variable section bar. On domestic passenger cars, cylindrical suspensions are used in suspensions. coil springs with constant bar section and pitch in combination with rubber impact buffers.

Torsion bars, as a rule, of round section are used on cars as an elastic element and a stabilizer. The elastic torque is transmitted by the torsion bar through splined or square heads located at its ends. Torsion bars on a car can be installed in the longitudinal or transverse direction. The disadvantages of torsion bars include their large length necessary to create the required stiffness and suspension travel, as well as the high alignment of the splines at the ends of the torsion bar. However, it should be noted that the torsion bars have a small mass and good compactness, which allows them to be successfully used on passenger cars of medium and high classes (for example, Renault-1 G, Fiat-130, in the suspension of the front wheels of Hongge Civic and etc.).

Pneumatic and pneumohydraulic elastic elements have not yet been found wide application in car suspensions. The use of gas as an elastic element has great prospects, since it allows, like no other elastic elements, to regulate the elastic characteristics of the suspension and ground clearance. Pneumohydraulic elastic elements have a metal shell in which the gas is compressed by a piston through a liquid that plays the role of a shutter, i.e. providing, together with the seals of the movable piston, the necessary tightness. In addition to Citroen, in Europe, for some class 8 vehicles, pneumohydraulic elastic elements are manufactured by Fichtel and Sachs.

Stabilizers on passenger cars, depending on the type and design of the suspension, can be various shapes: straight, U-shaped, arcuate, etc. The stabilizer is mounted on rubber bushings to ensure elastic deformation in the supports. As a rule, stabilizers are made of spring steel.

Dependent suspension on passenger cars is installed on rear wheels. Distinctive feature The design of the dependent suspensions used is the presence of elastic elements that transmit vertical loads and do not have friction, rigid rods and levers that perceive transverse (lateral) loads and provide the wheel and body with a certain kinematics.

In dependent suspensions, for the perception and transmission of lateral forces, a Panhard rod is used, which is a rigid bar, the ends of which are pivotally attached: one to the bridge beam, the other to the body. The location of this rod relative to the axis of the bridge and its length affect the position of the roll axis and the nature of the vehicle entering the turn, strengthening or weakening understeer or oversteer. The location of the Panhard rod behind the axis of the axle in the direction of travel helps to reduce the oversteer inherent in cars with rear wheel drive wheels, and the location in front of the axle helps to reduce the understeer inherent in front-wheel drive cars. The location of the thrust along the axis of the wheels has practically no effect on the steering of the car.

A characteristic design of the rear dependent suspension of a rear-wheel drive vehicle (classic layout) is the suspension of a VAZ car (Fig. 5) .

Two shock absorbers are installed in the suspension at an angle to the vertical axis of the car. Such an arrangement of shock absorbers provides, in addition to damping vertical vibrations, an increase in the lateral stability of the body. A similar installation of shock absorbers is adopted in the suspensions of Volkswagen, Opel, Ford, Fiat, etc. To perceive lateral forces, instead of Panhard rod, a number of cars use the Watt mechanism. Watt's mechanism can be located both along the axis of the carrier beam, and perpendicular to it.

On the Mazda-KX7 car, which has rear-wheel drive and dependent wheel suspension, the levers of the Watt mechanism are located along the axis of the bridge. The mechanism is located in front of the axle beam and, together with the trailing arms of the suspension, maintains neutral steering in corners, provides vertical movement of the axle and perceives lateral forces. Such a complication of the dependent suspension of a car with rear-wheel drive made it possible to reach speeds of up to 200 km / h on it. To ensure neutral steering, regardless of the axle load, the suspension of the drive wheels is used with oblique upper arms without transverse traction (Ford Taunus car).

The most advanced dependent suspension of the driving wheels of a car is used on a Volvo 740/760 car: the suspension has two long levers mounted under the bridge beam, on which a spring and a shock absorber are installed. The lower arms are attached to the body on rubber mounts that have some flexibility when twisting. Lateral forces are perceived transverse thrust Panhard, located behind the beam of the bridge at the height of the axle of the wheels.

The dependent rear suspension of vehicles with front-wheel drive consists of a carrier beam, most often an open profile, connecting the axles of the wheels, two or four trailing arms, pivotally or rigidly attached to the beam. The lower arms are made in such a way that elastic elements and shock absorbers rest on them. Lateral forces are usually taken up by Panhard's thrust.

The rear dependent suspension of the Saab-900 has a power beam, to which longitudinal (upper and lower) levers are hinged, forming the Watt mechanism. Above the power beam there is a Panhard rod, which perceives lateral loads and practically does not affect the steering of the car, as well as increasing the roll center, which is effective for front wheel drive vehicles. Location lower arms in front of the beam, and the upper ones behind it creates a loading of all levers by tensile forces during braking and parallel movement of the beam during body roll when cornering. The disadvantage of this suspension scheme is the displacement of the center of longitudinal roll when the load changes: at low load, the roll center is located in front of the wheel axle, and at full load - behind the axle. Such a change in the position of the center of longitudinal roll leads to a “peck” of the car during braking.

On a Ford Fiesta car, braking and traction forces are perceived by two lower trailing arms on a beam and brackets mounted on reinforced shock absorber rods and connected to the body through rubber bushings. Spring elastic elements are located on the power beam, and the shock absorber mounting brackets are moved back relative to the beam axis. This design of the suspension provides unloading of the middle part of the beam from torsional forces during acceleration and deceleration.

On some models of Renault and Daimler-Benz cars, there are two lower trailing arms and one upper triangular arm mounted on a beam with the possibility of rotation and angular misalignment. Such a scheme provides rectilinear movement rear axle no lateral shift and reduced body roll when cornering.

On cars "Audi-100", "Mitsubishi Talent", "Toyota Startet" the suspension of the rear driven wheels is used with two trailing arms working in bending (Fig. 6).

Traction and braking moments are transmitted through widely spaced levers, rigidly connected to the cross beam, and due to the perception of the bending moment by the levers and torsional loads, the longitudinal and transverse rolls body. Such a suspension is also used on Range Rover and Daimler-Benz vehicles, in the first case in the front suspension, in the second - in the front and rear suspensions of all-wheel drive vehicles.

On the AZLK-2141 vehicle, a suspension with a torsional transverse beam and trailing arms that perceive bending loads is also used, which differs from that shown in fig.7 the location of the elastic elements - springs directly on the levers.

The suspension design (in some cases it is called semi-dependent) with associated trailing arms has become widespread in passenger cars. The simplest variant of this design can be the suspension of the rear wheels of front-wheel drive VAZ cars. (Fig. 7) (including VAZ-1111), ZAZ-1102, Renault 5ST-turbo, Volkswagen Polo, Sirocco, Passat, Golf, Ascona, etc.

Rice. 7. Rear suspension of a VAZ-2109 car: 1 - hub rear wheel; 2 - rear suspension arm; 3 - bracket for mounting the suspension arm; 4.5 - rubber and spacer bushings of the lever hinge, respectively; 6 - a bolt of fastening of the suspension arm; 7 - body bracket; 8 - support washer for fastening the shock absorber rod; 9 - upper support of the suspension spring; 10 - spacer sleeve; 11- insulating gasket of the suspension spring; 12 - rear suspension spring; 13 - shock absorber rod mounting pad; 14 - compression stroke buffer; 15 - shock absorber rod; 16 - shock absorber protective cover; 17 - lower support cup of the suspension spring; 18 - shock absorber; 19 - connecting beam; 20 - wheel hub axle; 21 - hub cap; 22 - wheel hub nut; 23 - bearing washer; 24 - sealing ring; 25 - hub bearing; 26 - brake shield; 27,28 - locking and mud-reflecting rings, respectively; 29 - suspension arm flange; 30 - shock absorber bushing; 31 - bracket for mounting the shock absorber; 32 - rubber-metal hinge of the suspension arm

Such a suspension in front-wheel drive vehicles provides ease of layout of all suspension elements, a small number of parts in the suspension, the absence of guide levers and rods, optimal gear ratio from the body to the elastic suspension device, the exclusion of the stabilizer, high stabilization of the descent and track at different suspension travels, the favorable location of the roll centers, which reduce the possibility of "peck" of the body during braking.

The Volkswagen Golf and Sirocco cars have a simple suspension design with linked levers with a transverse link located close to the supports of the ends of the trailing arms (the camber change coefficient is close to unity).

The car "Renault-turbo" is equipped with a suspension with a cross-link and torsion elastic elements. Two torsion bars of different diameters are connected to each wheel (front - small diameter, rear - large), working simultaneously with an equilateral suspension stroke, and with a different one, the rear torsion bars and the cross member connecting the levers are loaded. Shock absorbers in the suspension are mounted at an angle to the vertical axis with a forward inclination, perceiving forces during braking and acceleration.

Double wishbone independent suspension is used on the front and rear wheels of cars. The suspension consists of two wishbones that articulate each wheel with the body, elastic elements, shock absorbers and stabilizer. At the front suspension, the outer ends of the levers are connected by means of ball joints to the pivot pin or fist. The greater the distance between the upper and lower guide arms, the more precise the suspension kinematics. The lower levers are made more powerful than the upper ones, since, in addition to the longitudinal forces, they also perceive the side ones. Suspension on double transverse levers allows, depending on the relative position of the levers, to provide the desired (optimal) location of the centers of transverse and longitudinal roll.

In addition, due to the different lengths of the levers (trapezoidal suspensions), it is possible to achieve different angular displacements of the wheels during rebound and compression strokes and to exclude changes in the gauge during relative movements of the body and wheels. An example of a double wishbone suspension is the front suspension of VAZ cars. (fig.8) . A similar design is used on cars "Opel", "Honda", "Fiat", "Renault", "Volkswagen", of course, with certain design features of the suspension elements.

Double wishbone suspension has been implemented in the designs of many cars, in particular, Daimler-Benz used a suspension similar to that shown in fig.8 on almost all cars. The front suspension of the Opel Cadet S car has a simple design, the guide device of which is rigidly attached to the body side members without rubber bushings. Cylindrical springs are mounted on the lower arms with an inclination to the longitudinal axis of the vehicle; elastic compression buffers are located inside the springs. The shock absorbers are mounted on the upper arms, the rebound buffers are located in the shock absorbers. Such an installation of springs and shock absorbers ensures uniform loading of the wheel joints. Together with the rack and pinion steering, the front suspension forms a separate mounting unit that allows for adjustment of camber, toe and caster before attaching to the body.

Rice. 8. Device(s) and typical scheme(6) VAZ-2105 front suspension: 1 - wheel hub bearing; 2 - cap; 3 - adjusting nut; 4 - axis of the pivot pin; 5 - hub; 6 - brake disc; 7 - rotary stand; 8 - upper lever; 9 - spherical bearing; 10 - buffer; 11 - reference glass; 12 - rubber cushions; 13, 26 - respectively, the upper and lower support cups of the spring; 14 - the axis of the upper arm; 15 - adjusting washer; 16, 25 - brackets for fastening the rod, respectively, stabilizer and shock absorber; 17 - rubber bushing; 18 - stabilizer bar; 19 - body spar; 20 - the axis of the lower arm; 21 - lower arm; 22 - suspension spring; 23 - clip; 24 - shock absorber; 27 - housing of the lower ball joint; 28 - wheel hub stud

The front suspension of the Honda Prelude has short upper wishbones located at an angle to the axle of the wheels. The lower arm is also located at an angle to the wheel axis (this angle is approximately three times smaller than the angle formed by the upper arm), together with the lower transverse arms, longitudinal rods are used, which are attached to the body through an elastic hinge.

Automobile "Alfa-90" has a torsion elastic element located longitudinally and connected with the lower lever of the guide device.

Citroen cars are equipped with pneumohydraulic elastic elements in the suspension (Fig. 9) . As noted earlier, such elastic elements provide "soft" suspension and the ability to adjust the ride height.

elastic element (Fig. 9, a) consists of a cylinder in which a piston with a long guiding cylindrical surface moves. A spherical cylinder is installed in the upper part of the cylinder, divided by an elastic diaphragm (membrane) into two cavities: the upper one is filled with compressed nitrogen, the lower one is filled with liquid. A shock-absorbing valve is located between the cylinder and the cylinder, through which fluid is passed during rebound and compression. The design of the elastic element allows you to install it in the suspension in any position. In particular, on the rear suspension of the car "Citroen-BX" the elastic elements are installed at a slight angle to the horizontal, the force is transferred to them through a spherical support by the brackets of the trailing arms of the suspension guide. The use of pneumohydraulic elements in the suspension of passenger cars allows you to have a natural frequency of oscillation of the body, depending on the load, in the range of 0.6-0.8 Hz.

On Mercedes 20 (Yu / ZOOE) cars, a suspension on double transverse spatial levers is used. Such a suspension consists of articulated paired levers that make up a triangle in a top view, with an intersection point in the structural center of the axis of rotation (on the axis of symmetry of the wheel). Such a design suspension, given the presence of elastic elements in the support nodes, provides a high level of safety when turning the car at high speeds.

Suspension on guide posts (MacPherson suspension, see Fig. 2,e) used in almost most passenger cars manufactured by various foreign firms. On domestic cars, the most characteristic design suspension on guide racks is the front suspension of front-wheel drive cars VAZ (fig.10) and AZLK.

The front suspension of the VAZ-2109 car consists of a telescopic shock absorber strut, on the upper part of the body of which a cylindrical spring of an elastic element is installed, and on the rod there is a buffer for the compression stroke of the transverse lever, pivotally connected to the body by the steering knuckle of the strut, stretch marks and anti-roll bar.

Audi, Volkswagen, Opel, Ford, "Audi" cars have a similar structural and kinematic scheme of the front suspension. Daewoo Nexia" and many others.

The advantage of a suspension with a guide post is the assembly compactness of the elements that perform elastic, guiding and damping work, as well as small forces in the attachment points of the suspension to the body, the possibility of using long-stroke suspensions that provide the best ride smoothness, the ability to create optimal kinematics, the convenience of creating good vibration and noise insulation of the body, low sensitivity to imbalance and runout of tires, etc.

Rice. 10. Front suspension of a VAZ-2109 car: 1 - car body; 2 - upper support cup; 3 - compression stroke buffer; 4 - buffer support; 5 - suspension spring; 6 - lower support cup of the spring; 7 - ball joint steering rod; 8 - rotary lever; 9 - telescopic stand; 10 - eccentric washer; 11 - adjusting bolt; 12 - rack bracket; 13 - rotary fist; 14 - fixing bolt; 15 - casing; 16 - retaining ring; 17 - wheel hub cap; 18 - spline drive shank; 19 - wheel hub; 20 - wheel hub bearing; 21 - brake disc; 22 - suspension arm; 23 - adjusting washer; 24 - stabilizer bar; 25 - anti-roll bar; 26 - stabilizer cushion; 27 - stabilizer mounting bracket; 28, 31 - brackets; 29 - stretching the suspension arm; 30 - washers; 32 - rubber expansion bushing; 33 - sleeve; 34 - protective cover of the ball pin; 35 - ball pin bearing; 37 - body of the ball pin; 38 - suspension rod; 39, 40 - housings of the upper support; 41-45 - elements of the upper support; 46 - bolt; / - upper support; // - ball pin of the suspension arm; /// - front hinge stretching the suspension arm; a - controlled gap

Consider some of the design features of the suspension with a guide post. Analyzing the kinematics of the suspension, one can see that the position of the roll center depends on the angle of inclination of the rack to the vertical and the lower arms to the horizon. The selection of the installation of the rack and the levers can ensure the position of the roll center under various loads is much lower than when using the suspension on double wishbones. The angular position of the rack also affects changes in camber and track. When the rack is located close to the vertical and the long lower transverse arm, the track will practically not change. It should be noted that the change in camber under the action of lateral forces at the turn is much smaller than in suspensions on double wishbones.

To prevent jamming of the shock absorber piston, the spring on the strut is installed with an inclination so that the axis of the spring installation passes through the bearing hinge of the lower arm.

On BMW cars 5 -1st series, a front suspension with double joints is used. The elastic elements-springs with their lower part rest on cups welded to the shock absorber body, with the upper part of the spring rest against ball bearing attached to the body at three points. The guiding device consists of transverse levers that perceive lateral loads and rods directed forward at an angle to the longitudinal axis of the vehicle and ensure that the steered wheels turn in the direction of positive convergence, i.e. improved linear stability. The mutual position of the support hinges of the levers and rods allows you to increase the resistance to longitudinal roll during acceleration and braking. The suspension of the driven wheels of the car "Honda Prelude" consists of transverse levers great length and longitudinal bars directed at a slight angle to the longitudinal axis. The arm mounting supports in the wheel area are located approximately in the center of the wheel, thereby achieving an optimal location of the lateral roll center.

Suspension on the trailing arms of the guide device (see Fig. 2d) consists of a powerful, usually welded box-shaped or cast lever 5 (Fig. 11) guiding device located in the direction of travel on each side of the vehicle.

The lever perceives torsional and bending loads that occur when the vehicle is moving. To ensure the necessary rigidity of the suspension with lateral forces, the arm has widely spaced supports on the body. Trailing arm suspension is often used in the rear suspension of front wheel drive vehicles. The horizontal position of the levers ensures that the camber, wheel alignment and track remain unchanged during the compression and rebound strokes. The length of the levers affects the progressiveness of the elastic characteristics of the suspension, and since the swing points of the levers are the centers of the longitudinal roll of the car, the body will "squat" when braking.

Suspension with trailing arms are equipped with cars "Renault", "Citroen", "Peugeot", etc.

Springs, torsion bars and pneumohydraulic devices are used as elastic elements in suspensions. Spring elastic elements can be located both coaxially with the shock absorber ("Peugeot"), and in parallel ("Mitsubishi Colt", "Talbot"). On some models of Peugeot cars, the spring struts are located at a slight angle to the horizontal, and the elastic elements are similarly installed on the Citroen BX car. Rear suspension with torsion bars (see fig. 11 ) is compact. torsion bars 2 engage with guide tubes 1 and 7 . Cast trailing arms 5 welded to pipe ends 1 and 7 nested one inside the other and separated rubber bushings 8 and 9 .

Wishbone suspension (see Fig. 2, f) It is used only in the rear suspension of cars. Suspension BMW cars 5 th series is shown on fig.12 , a similar guide device is installed on Fiat, Daimler-Benz, Ford cars with some design features.

The most favorable, from the point of view of the kinematics of the suspension, is the sweep angle in the range of 10-25 ° (the angle between the transverse axis and the position of attachment to the body of the guide device lever in the horizontal plane). For example, this angle is for cars: BMW 5181/5251 and BMW 5281/5351 - 20°; "Ford Sierra / Scorpio" -18 °, "Opel Senator" - 14 °, etc. With this design of the guide device of the drive wheels between the wheel and final drive(differential) there are angular and linear movements that require installation in the axle shafts that transmit torque to the wheels, two hinges of equal angular velocities to compensate for these movements. Depending on the ratio of the lengths of the oblique arms and the angles of their installation, almost any required position of the roll centers and a reduction in track changes can be obtained. In such suspensions, the shock absorber is installed with an offset to the wheel axis, which can provide a gear ratio from the wheel to the shock absorber equal to one.

Additional elastic suspension elements, installed in addition to the main elastic elements, perform two tasks: noise and vibration isolation of the body and limitation of the suspension travel during compression and rebound with the corresponding progressive provision of the elastic characteristics of the suspension. The main requirement in this case for the elastic elements will be the creation of a certain elasticity in the axial direction and high rigidity in the radial direction in order to exclude the influence on the kinematics of the suspension. Such additional elastic elements are made, as a rule, from rubber and various elastic polymers (for example, polyurethane). In front steered wheel suspensions in top support spring struts mounted ball bearing (see fig. 10)- to eliminate friction when turning the wheels, as they turn together with the racks. On fig. 4.13 shows the upper elastic supports of the pillars of the Volvo-740/760 and Mercedes-190 cars.

in support Fig. 13, a rubber bearings are designed in such a way that the forces from the spring and the shock absorber are perceived separately. Through the thrust ball bearing, the suspension spring acts on the rubber buffer 5 . The shock absorber rod is mounted in the sleeve 1 through which it affects middle part rubber buffer 5. A similar buffer design is used on the Peugeot car, only in a somewhat simplified design of the rubber buffer itself. On the Fig. 13b rubber support 5 designed mainly for noise insulation, and the elastic element 6 is placed on the shock absorber rod and transmits the compression force through the inner cap of the support 5 point blank 4 and body. This design increases the guide base of the shock absorber and prevents the possibility of stem jamming.

Lecture 14, 15.

Steering

The road along which the driver chooses the route of movement is not always flat and smooth. Very often, there may be such a phenomenon as surface irregularities - cracks in the asphalt and even bumps and potholes. Do not forget about the "speed bumps". This negative would have a negative effect on the comfort of movement, if there were no depreciation system - the suspension of the car.

Purpose and device

During the movement, the roughness of the road in the form of vibrations is transmitted to the body. The vehicle's suspension is designed to dampen or mitigate such vibrations. Its application functions include providing communication and connection between the body and the wheels. It is the suspension parts that give the wheels the ability to move independently of the body, providing a change in the direction of the car. Along with the wheels, it is an indispensable element of the chassis of the car.

The suspension of a car is a technically complex unit having the following structure:

1. elastic elements - metal (springs, springs, torsion bars) and non-metal (pneumatic, hydropneumatic, rubber) parts, which, due to their elastic characteristics, take the load from road irregularities and distribute it to the car body;
2. damping devices (shock absorbers) - units having a hydraulic, pneumatic or hydropneumatic structure and designed to level body vibrations received from an elastic element;
3. guide elements - various parts in the form of levers (transverse, longitudinal), providing connection of the suspension with the body and determining the movement of the wheels and the body relative to each other;
4. anti-roll bar - an elastic metal bar that connects the suspension to the body and prevents the car from increasing roll during movement;
5. wheel supports - special steering knuckles(on the front axle), perceiving the loads emanating from the wheels, and distributing them to the entire suspension;
6. fastening elements of parts, components and assemblies of the suspension are means of connecting the suspension elements to the body and to each other: rigid bolted connections; composite silent blocks; ball joints (or ball bearings).

Principle of operation

The scheme of operation of the car suspension is based on the conversion of the impact energy arising from the impact of a wheel on an uneven road surface into the movement of elastic elements (for example, springs). In turn, the rigidity of the movement of the elastic elements is controlled, accompanied and softened by the action of damping devices (for example, shock absorbers). As a result, thanks to the suspension, the impact force that is transmitted to the car body is reduced. This ensures smooth running. The best way to see the operation of the system is to use a video that clearly demonstrates all the elements of the car's suspension and their interaction.

Cars have a variety of suspension stiffness. The stiffer the suspension, the more informative and more efficient management by car. However, comfort suffers greatly. And vice versa, soft suspension designed in such a way that provides ease of use and sacrifices handling (which should not be allowed). That is why car manufacturers are striving to find their most optimal option - a combination of safety and comfort.

Variety of suspension options

The vehicle suspension device is an independent design solution of the manufacturer. There are several typologies of car suspension: they are distinguished by the criterion underlying the gradation.

Depending on the design of the guide elements, the most common types of suspension are distinguished: independent, dependent and semi-independent.

A dependent option cannot exist without one detail - a rigid beam that is part of the vehicle's axle. In this case, the wheels in the transverse plane move in parallel. The simplicity and efficiency of the design provides it high reliability, avoiding the collapse of the wheels. That is why the dependent suspension is actively used in trucks and on the rear axle of cars.

The scheme of independent suspension of the car assumes the autonomous existence of the wheels from each other. This allows you to increase the damping characteristics of the suspension and provide greater smoothness. This option is actively used to organize both the front and rear suspension on cars.

The semi-independent version consists of a rigid beam fixed to the body with torsion bars. This scheme provides the relative independence of the suspension from the body. Its typical representative is front wheel drive models VAZ.

The second typology of suspensions is based on the design of the extinguishing device. Specialists distinguish hydraulic (oil), pneumatic (gas), hydropneumatic (gas-oil) devices.

The so-called active suspension stands out in a certain way. Its scheme includes variable possibilities - changing the suspension parameters using a specialized electronic control system, depending on the driving conditions of the car.

The most common parameters to change are:

• the degree of damping of the extinguishing device (shock absorber device);
• the degree of rigidity of the elastic element (for example, springs);
• the degree of rigidity of the anti-roll bar;
• length of guide elements (levers).

Active suspension is an electronic-mechanical system that significantly increases the cost of the car.

The main types of independent suspension

In modern passenger cars, an independent suspension option is very often used as a shock-absorbing system. This is due to the good handling of the car (due to the small mass) and the lack of need for total control behind the trajectory of its movement (as, for example, in the variant with freight transport).
Experts distinguish the following main types of independent suspension. (By the way, the photo will allow you to more clearly analyze their differences).

Suspension based on double wishbones

The structure of this type of suspension includes two levers attached to the body with silent blocks, and a shock absorber and a coil spring located coaxially.

MacPherson pendant

This is a derivative (from the previous view) and a simplified version of the suspension, in which the upper arm has replaced suspension strut. To date, MacPherson strut is the most common front suspension scheme for passenger cars.

Multi-link suspension

Another derived, improved version of the suspension, in which, as it were, artificially, the two transverse levers were “separated”. Besides, modern version suspension very often consists of trailing arms. By the way, multi-link suspension- This is the most used rear suspension scheme for passenger cars today.

The scheme of this type of suspension is based on a special elastic part (torsion bar), which connects the lever and the body and works on twisting. This type of design is actively used in the organization of the front suspension of some SUVs.

Front suspension adjustment

An important component of comfortable driving is the correct adjustment of the front suspension. These are the so-called steering angles. In colloquial speech, this phenomenon is referred to as "descent-collapse".

The fact is that the front (steered) wheels are not installed strictly parallel to the longitudinal axis of the body and not strictly perpendicular to the road surface, but with certain angles that provide slopes in the horizontal and vertical planes.


Correctly set "similarity-collapse":

• firstly, it creates the least resistance to the movement of the vehicle, and, therefore, simplifies the process of driving;
• secondly, it significantly reduces tire tread wear; thirdly, it significantly reduces fuel consumption.

Setting corners is a technically complex procedure that requires professional equipment and skills. Therefore, it should be performed in a specialized institution - a car service or service station. It is hardly worth trying to do it yourself using a video or photo from the Internet if you have no experience in such matters.

Suspension malfunctions and maintenance

Let's make a reservation right away: according to Russian legal norms, not a single suspension malfunction is included in the “List ...” of malfunctions with which movement is prohibited. And this is a moot point.

Imagine that the suspension damper (front or rear) does not work. This phenomenon means that the passage of each bump will be associated with the prospect of body buildup and loss of vehicle controllability. And what can be said about the completely loose and worn-out ball bearing of the front suspension? The result of a part malfunction - “a ball has flown out” - threatens with a serious accident. A broken elastic suspension element (most often a spring) leads to body roll and sometimes an absolute impossibility to continue moving.

The malfunctions described above are already the final, most odious malfunctions of the car's suspension. But, despite their extremely negative impact on traffic safety, the operation of a vehicle with such problems is not prohibited.

An important role in the maintenance of the suspension is played by monitoring the condition of the car in the process of movement. Squeaks, noises and knocks in the suspension should alert and convince the driver of the need after-sales service. And the long-term operation of the car will force him to apply a radical method - “change the suspension in a circle”, that is, replace almost all parts of both the front and rear suspension.

pendants Vehicle are classified according to the types of guide devices, elastic elements and damping devices (shock absorbers).

By type of guides

According to the type of guide devices, suspensions are distinguished:

• dependent
• independent
• balancing

In dependent suspension with a cross-link, the wheels of two sides of one bridge are connected by a rigid beam (see Fig. a). In this case, the vertical movement of one wheel relative to the carrier system causes a change in the inclination of the rolling plane of the other wheel.

In independent suspension each wheel (skating rink) moves relative to the carrier system independently of the other. Figure b shows an independent single wishbone suspension with a transverse arm. Such a guide device ensures the movement of the wheel in the transverse plane with a change in the angle of its inclination and the track of the vehicle. Depending on the design independent suspensions can be single-lever with a longitudinal arrangement of the lever (figure a) and double-lever with a transverse arrangement of levers (figure b).

Single lever suspension with trailing arm completely eliminate the change in the angle of inclination of the wheel and the track of the vehicle, and the double-lever ones provide their minimum changes when right choice the ratio of the lengths of the levers and the angles of their installation.

In balance beams(in dependent suspensions with a longitudinal connection) the wheels (rollers) of one side of the vehicle are connected to each other by swinging balancers, the role of which can be played by leaf springs or rigid beams (Fig. a, b). In such suspensions, even in the absence of an elastic element, the vertical movement of one of the wheels causes half the movement of the swing axis of the balancer mounted on the carrier system of the vehicle, which improves the smoothness of the machine. Balancing suspensions, due to the rocking of the balancer, provide a redistribution of the load acting on the wheels, which significantly reduces the impact of road irregularities on the vehicle as a whole.

Rice. Schemes of independent suspensions:
a - single-lever with a longitudinal arrangement of the lever; b - double-sided with transverse levers

By type of elastic elements

According to the type of elastic elements, suspensions with elastic elements are distinguished:

• metal
• non-metallic

As metal elastic elements leaf springs, coil springs (cylindrical or conical) and torsion bars are used. Non-metallic elastic elements include pneumatic and rubber elastic elements.

The leaf spring consists of several steel sheets (most often 6 - 14) having different lengths and curvature and, as a rule, a rectangular section. tough.

Rice. Schemes of balancing suspensions:
a - with an elastic balancer in the form of a leaf spring; b - with a rigid balancer; AB, DC - reactive and pushing rods, respectively

In the manufacture of leaf springs, the sheets are given different curvature, therefore, during assembly, they are subjected to preliminary deformations, the sign of which is opposite to the sign of working deformations. This provides some unloading of the leaf springs. The sheets are assembled into a package using clamps, some springs are pulled together with a central bolt and then installed between the axle and the carrier system of the machine. Leaf springs are usually semi-elliptical in shape.

If the leaf spring is used in a dependent cross-link suspension, its middle part is attached to the bridge beam with the help of ladders, and the ends are hinged (using special brackets) to the carrier system of the machine. The front end of the spring is fixedly attached to the frame bracket with a pin, and the rear end has a sliding connection in the bracket inserts. In some cases, the ends of the springs are connected to the carrier system using rubber pads fixed in the brackets, thus providing a fixed connection of the front end and a sliding connection of the rear end of the spring. In this design of the suspension, the spring simultaneously acts as an elastic element and a guide device, i.e. through it, forces acting in the horizontal plane and moments from them are transmitted from the propulsion system to the carrier system.

If the spring is used in a balancing suspension, its middle is attached with stepladders to a hub mounted on a frame support, which is the swing axis of the balance beam. The ends of the springs rest on brackets - bridge supports. The design of the brackets ensures the sliding of the ends of the spring in the longitudinal direction and a rigid connection with the bridge in the transverse direction.

Communication in the longitudinal direction, as well as the transfer of reactive moments, are carried out using pushing and reactive rods connecting the beams of the bridges with the carrier system. In order to ensure free movement of the beams of the bridges in the vertical direction and to allow some distortions, the ends of the rods are connected to the bridges and the frame by ball joints. In order for the forces acting from reactive moments along the reaction rods not to reach large values, the attachment points of the ends of these rods to the axle beams are moved as high as possible from the axis of rotation of the wheels by installing special brackets on the axle beams.

During the operation of leaf springs, a relative movement of the sheets occurs in the longitudinal direction and interleaf friction is created, which, on the one hand, contributes to the damping of vibrations, and on the other hand, adversely affects the smoothness of the vehicle due to suspension blocking at high friction forces. To reduce friction, the spring leaves are lubricated with graphite grease during assembly or non-metallic anti-friction gaskets are used between the sheets. Reducing the friction force is also achieved by reducing the number of sheets in the spring and using a spring consisting of a single sheet with a variable cross section along its length. The use of single-leaf or small-leaf springs reduces the consumption of metal, which, in turn, reduces the weight of the suspension.

Coil springs as the main elastic elements are usually installed on cars in independent link suspensions. In heavy-duty vehicles, springs are used as auxiliary elastic elements, for example, as travel stops torsion bar suspensions tracked vehicles. Most often, cylindrical and conical springs of round or rectangular sections are used.

Torsion elastic elements, or simply torsion bars, are rods of various cross sections made of high-quality steel, working in torsion. They are used in independent suspensions and, unlike leaf springs, require guides. At the ends of the torsion bars there are usually heads with slots. One end of the torsion bar is fixed in a special bracket on the carrier system of the machine, and the other end is connected through the guide lever to the wheel (roller). When moving the wheel in the vertical direction, the torsion bar twists at an angle of up to 30 ... 45 °, thereby ensuring the elasticity of the suspension.

According to the location on the vehicle, torsion bars are distinguished:

• longitudinal
• transverse

In pneumatic suspensions, compressed air or nitrogen is used as an elastic element, enclosed in a rigid or elastic shell. When the wheel moves relative to the carrier system, the volume of gas changes. The nature of this change determines the elastic characteristic of the suspension.

Pneumatic elastic elements, in which the gas is enclosed in an elastic shell, are rubber-cord shells sealed at the ends and filled with air under pressure. Three types of these elements are used in the vehicle: air springs, sleeve and diaphragm elastic elements.

Pneumocylinders are made one-, two- and three-section. A two-section air spring (Fig. a) consists of a shell 1 with a thickness of 3 ... 5 mm, reinforced with steel wire rings 2 for fastening to support flanges 4 using rings 3. In the middle part, the shell is pulled together by ring 5.

Rice. Pneumatic elastic elements with gas enclosed in an elastic shell:
a - two-section pneumocylinder; b - sleeve type element; c - a schematic diagram of the regulation of the position of the body

Sealing of the shell of the sleeve elastic element (Fig. b) is carried out using clamping flanges 6 or under air pressure.

The diaphragm elastic element differs from the sleeve element by the presence of a rigid side shell. The lower end part of its shell is an elastic diaphragm. The cord fabric of the shell is made of polyamide threads (nylon, capron).

Pneumatic elastic elements with gas enclosed in a rigid shell are divided into three types: with one pressure stage (Fig. a), when the compressed gas is located above piston 1 in one volume (chamber A); with counterpressure (Fig. b), when the gas is both in the above-piston space (chamber A) and under piston 1 (chamber B), and the gas pressure is greater in chamber A; with two pressure stages (fig. c), when two chambers A and B are located above the piston 7. In the latter case, the charging pressure of the gas chambers is different. In chamber A, the gas is compressed during the entire suspension stroke, and in chamber B, the gas begins to compress when a pressure greater than the charging pressure of this chamber is reached.

The transfer of forces from the piston to the gas is carried out through the liquid with which the cylinder is filled. In some cases, the liquid is in direct contact with the gas (chamber B in Fig. b), but most often it is separated from the gas by a flexible separator (diaphragm) 3 or a floating piston 13 shown in the figure.

With direct contact of the liquid with the gas during the operation of the suspension, foaming occurs, which adversely affects the characteristics of the elastic element.

Rice. Schemes of pneumatic elastic elements with gas, enclosed in a rigid shell, with one pressure stage (a), with counterpressure (b) and with two pressure stages (c)

The use of liquid in such elastic elements provides damping of vehicle mass oscillations when it flows through calibrated holes and valves 2. Thus, an assembly is obtained in which both the elastic element and the shock absorber are located.

The figure shows the device of a pneumatic elastic element with one pressure stage, which does not have damping properties, but has additional rubber elastic elements 7. Filling with gas and liquid is carried out, respectively, through valves 19 and 27. The elastic elements work at the beginning and end of the suspension stroke. The gas is separated from the liquid by a floating piston 13. The elastic element through the earring 1 and the bearing 2 is attached at one end to the suspension guide, and at the other end to the carrier system of the machine.

The use of pneumatic elastic elements allows you to adjust the position of the body and ground clearance, as well as change the elastic characteristics of the suspension.

A schematic diagram of the regulation of the height of the vehicle body by the mass of gas in the elastic element is shown in figure c. As the load increases, the car body lowers and the distance between it and the axle decreases. The lever drive, acting on the regulator 8, ensures the communication of the elastic element 7 with the receiver. Air under pressure enters the elastic element until the body rises to its previous level. When the load decreases, the distance between the body and the bridge will also remain unchanged, since with the help of the regulator 8, air is released from the elastic element 7 into the atmosphere. The use of a hydraulic retarder built into the regulator eliminates the operation of the regulator when the vehicle oscillates on the suspension.

The height of the body can be adjusted by changing the volume of liquid between the gas and the piston. In these systems, to raise the body of the vehicle, the liquid is injected into the elastic element, and to lower it is removed.

On a number of vehicles there is a system for regulating the position of the body, with which you can not only change the ground clearance of the entire car, but also give the body a trim for the bow or stern or roll on board by selecting the parameters of the corresponding suspensions.

Rubber elastic elements are used in vehicle suspensions as suspension travel stops and in shock absorber attachment points, reducing the dynamic loading of suspension parts and the carrier system.

As damping devices in the TS, they are used, in which the mechanical energy of the TS vibrations is converted into thermal energy by liquid friction when a viscous liquid passes through holes of small cross section. The liquid heats up and the heat is dissipated in the surrounding space.

Structurally, hydraulic shock absorbers are telescopic and lever. Telescopic ones operate at liquid pressure up to 8 MPa, and lever ones - up to 30 MPa. Telescopic shock absorbers are divided into two-tube and one-tube. Lever can be piston and bladed.

Rice. Pneumatic elastic element with additional elastic elements:
1 - earring; 2 - articulated bearing; 3, 15, 17 - seals; 4, 8 - glasses; 5 - case; 6, 11, 14 - washers; 7 - additional elastic elements; 9 - piston; 10 - cylinder; 12 - cuff; 13 - floating piston; 16 - cover; 18 - bushing; 19, 21 - charging valves; twenty - bypass valve

Mineral oils are used as workers.

During the operation of the shock absorber, a compression stroke and a rebound stroke are distinguished. During the compression stroke, the wheel (skating rink; approaches the carrier system of the vehicle, and during the rebound, on the contrary, moves away from it.

The device and principle of operation of a double-acting hydraulic telescopic double-acting shock absorber

Consider the device and principle of operation of a double-acting hydraulic telescopic double-acting shock absorber. The shock absorber with eye 6 is attached to the carrier system of the machine, and with eye 1 - to the guide device. The shock absorber consists of a rod 5, at the lower end of which a piston 8 is fixed with valves and channels calibrated in cross section. The piston is located inside the working cylinder 12, which is enclosed in the outer tube 13 and fastened to it. Between the outer cavity of the cylinder and inner surface pipes there is a gap forming a compensation chamber 3 of the shock absorber. In the upper part of the cylinder there is a seal through which the rod passes. The lower part of the cylinder is connected to the compensation chamber by valves and calibrated channels.

In the piston there are calibrated holes 4 of the rebound stroke, a bypass valve 7 of compression and an unloading valve 9 of rebound.

In the lower part of the cylinder there is a release valve 10, a calibrated compression channel 2 and a compression relief valve 11. During the compression stroke, when the rod moves into the cylinder, the pressure under the piston rises, and the liquid flows through the hole 4 and the valve 7 into the space above the piston. Due to the fact that the volumes of the cavities under the piston and above it are not the same (part of the volume above the piston is occupied by the rod), excess liquid flows through channel 2 into the compensation chamber, compressing the air present there. At a high speed of movement of the piston in the cylinder, the pressure under it rises so much that it compresses the spring of the unloading valve 11, which opens, and the pressure increase decreases, which limits the resistance force of the shock absorber during compression. During the rebound, when the piston moves out of the cylinder, the pressure above the piston increases and the liquid flows through the calibrated holes 4 into the space above the piston. The liquid deficit under the piston will be covered by its flow from the compensation chamber to the cylinder through valves 10 and channel 2. At a high piston speed during the rebound stroke, the pressure above the piston increases, which causes the opening of the rebound relief valve 9 in the piston and thereby limits the resistance force of the shock absorber to during the retreat.

Rice. Scheme of a hydraulic telescopic double-acting double-acting shock absorber

The normal condition for the operation of the shock absorber is the absence of air inclusions in the fluid. In the considered shock absorber, air inclusion can occur due to agitation of the liquid in the compensation chamber, where the liquid is in contact with air.

This drawback does not have a double-acting hydraulic telescopic single-tube shock absorber, in which two valves (rebound 3 and compression 2) are located in the piston, and the role of the compensation chamber is performed by cavity A, separated from the under-piston space by a floating piston 7. In cavity A there is compressed gas, the volume which decreases during compression and increases during rebound.

In lever shock absorbers, the lever is connected at one end to the suspension guide, and at the other - to the piston or blade. When the latter move inside the shock absorber body, fluid from one cavity flows into another through valves and holes, the sections of which determine the rebound and compression characteristics.

Along with the considered shock absorbers, there are those in the design of which it is possible to control the parameters that determine their damping properties by changing the total area of ​​the holes through which the working fluid flows. Regulation is carried out by changing the mass of the machine or the intensity of vibrations. With an increase in the values ​​of these parameters, the resistance of the shock absorbers increases.

Rice. Scheme of a hydraulic telescopic double-acting single-tube shock absorber

Avoiding technical terms, we can say that the suspension is necessary in order to reduce the impact of road bumps on the car body. For this, elastic elements are provided in the design of the suspension. These include springs, springs, and rubber elements (chippers, buffers, silent blocks). There are also pneumatic and hydropneumatic elastic elements.

Metal elastic elements

Springs

Springs, as an elastic suspension element, are currently used in the vast majority of cars. Made of round metal rod, they have a constant stiffness characteristic and perfectly cope with the task assigned to them. The coils converge evenly as the load increases and return to starting position when it is removed.

If there is a need for variable stiffness, then the springs are made from a bar of various diameters (in certain areas), or in the form of a barrel (some coils are narrower). In this case, when the spring receives a load, the coils of smaller diameter (thickness) will approach first.

The advantage of the spring, as an elastic element, is the ease of manufacture, which means the final cost of the product, and its low weight. But since it cannot transmit forces in the transverse plane, it requires the vehicle suspension to have complex guiding devices. Which in turn affects both the price and the weight of the entire assembly.

springs

Another elastic element of the car's suspension are leaf springs. Due to the large weight compared to the same springs, the springs are mainly used in the suspension trucks. The spring consists of metal sheets (very rare cases reinforced plastic), of various lengths and shapes, interconnected by a bolt in the center, and clamps closer to the edges. Being equal in width, each plate, depending on the length, has a different degree of convexity. This provides the spring with the necessary characteristics. The longest (root) plate is attached to the car body or frame.

There are several basic ways to attach the spring to the body:

• with twisted ears;
• sliding support and false ears;
• rubber pads.

Each of the mounting methods has its own characteristics and characteristics. General requirement to any of the listed methods of fastening - the ends of the plates must be able to move and rotate. During the operation of the spring suspension, the sheets rub against each other. This requires the use of additional lubrication, or the presence of anti-friction gaskets.

Rubber elastic elements of the car suspension

These elements play an auxiliary role in the operation of the suspension, however, they can also be attributed to elastic elements. They primarily help to avoid hitting the metal parts of the suspension against each other, thereby minimizing the noise level. They also increase the rigidity of the main elements and limit the degree of their deformation.

Rubber elements do an excellent job of both compression and rebound. So, for example, polyurethane bumpers installed in the shock absorber strut work great for rebound.
The different shape, as in the case of a spring, determines the performance of the rubber element. The shape of the cone allows for smooth performance, first the thin, upper part is compressed, the closer to the thick part, the more elastic the rubber becomes.

Today, step-shaped fenders are often found, having alternating thin and thick parts. This allows you to significantly increase its working stroke.

Pneumatics and hydropneumatics

Air suspension is used in both cars and trucks. passenger transport. Pneumatic elastic element, allows you to change the stiffness of the suspension depending on the traffic situation, vehicle load. In modern cars, air suspension controls the electronics, which is able to independently monitor its work, and change its rigidity depending on the situation.

Pneumatic elements

Pneumatic elements (air cylinders) change their severity due to the air pressure created inside the compressor. The cylinders are made of oil-resistant and air-tight rubber, contain cord and metal threads, which makes them more rigid and reliable. Hence the name - rubber-cord elastic elements. The wall thickness of such a cylinder is usually from 3 to 5 mm.

Hydropneumatic elements

This elastic element provides the greatest comfort for the driver and passengers of the car, as it does an excellent job of damping suspension vibrations. The hydropneumatic elastic element is a chamber with two cavities. One of them is filled with gas, and the other with liquid, which, as you know, have different degrees of compression. Through a complex system of membranes and valves, liquid and gas interact to varying degrees (depending on the situation), which provides the necessary comfort and elasticity of the car's suspension.

The ubiquity of this pendant is limited, perhaps, only by its high cost.

Progress does not stand still, and every year engineers are getting closer and closer to creating a suspension that is ideal in all respects and will meet all the necessary requirements. Perhaps not far off is the day when being in the car (when driving on the most terrible off-road), in terms of comfort, can be compared with sitting on a soft sofa.