Dependent suspension anatomy

Dependent suspension is widely used in trucks, buses and cars (rear suspension). In most cases, trucks and buses have a guiding device combined with an elastic element in the form of longitudinal semi-elliptic leaf springs.

The front suspension of the truck consists of two longitudinal semi-elliptic leaf springs located under the frame side members along the vehicle. The ends of the double root leaf of the spring are fixed with rubber supports in the brackets attached to the spar. The ends of one root sheet are bent up, and the other down, so that a persistent end surface is formed. The ends of the sheets are covered by clips, increasing the pressure area of ​​the spring on the rubber supports, which reduces their wear.

The spring is assembled from steel sheets of different lengths, which are pulled together with clamps and attached to the front axle with two stepladders. Using these same step-ladders, a rubber buffer is attached to the upper part of the spring, softening impacts at maximum spring deflections. The front suspension also includes a hydraulic telescopic shock absorber, which connects the front axle and the frame side member bracket with the help of a single-axle metal hinge.

The rear dependent suspension of the vehicle has two main springs with additional springs (springs) located along the frame side members in the rear of the car. The main rear spring is attached to the frame, as well as the front spring, with the help of the lower and upper rubber supports. The front end of the spring abuts against an additional end stop. The load on the additional spring is transmitted through the brackets mounted on the side members.


For an unloaded vehicle with a small deflection of the rear springs, forces are transmitted only by the main springs, and between the brackets of the additional spring and its ends there is a gap that decreases as the load increases. At full load, an additional spring comes into operation, the elasticity of which can vary, since the ends of the upper leaf of the spring slide along the convex supports and the length of the working part of the spring decreases as it bends.

Four side clamps prevent lateral displacement of the main spring sheets, and two two clamps prevent the additional. The main and additional springs are connected to the rear axle using the lining and stepladders.

To increase durability, the leaves of the springs are shot blasted. The large friction between the spring leaves makes the suspension unnecessarily stiff, so all the sheets of the front and rear springs are lubricated with graphite lubricant, which reduces friction and protects them from corrosion.

In some vehicles, the springs are mounted in a different way – on their front ends with the help of bolts and step ladders, removable ears are fixed with which the springs are fixed in brackets with fingers. The rear springs are free to mix between the support crackers and bushings in the brackets. In the rear dependent suspension of the drive axle of passenger cars, coil springs are used as elastic elements installed in cups on the bridge beam and through rubber vibration-isolating gaskets on the body. Compression stroke limiters are mounted coaxially with the springs.

There is an additional rubber buffer that prevents hard blows of the front part of the main transmission case against the body during large deflections of the suspension in combination with the rotation of the bridge, due to the flexibility of the rubber bushings for attaching the rods during intensive acceleration of the car.

The guiding device is two upper, two lower and transverse rods (rods) installed between the bridge and the body and fixed in rubber-metal hinges. Longitudinal rods, working together, perceive longitudinal forces. The cross bar only balances the lateral forces. The upper rods are shorter than the lower ones, and the lengths of the rods and their ratio are selected in such a way as to ensure stable operation of the rear universal joint and spline connection of the universal joint shaft.

Rear Suspension:

1 – spacer sleeve; 2 — rubber sleeve; 3 – lower longitudinal bar; 4 – lower insulating gasket of the spring; 5 – lower support spring cup; 6 – compression stroke buffer; 7 – a bolt of fastening of the top longitudinal bar; 8 – bracket for attaching the upper longitudinal bar; 9 – a suspension spring; 10 – the upper spring cup; 11 – upper insulating gasket of the spring; 12 – supporting cup spring; 13 – thrust of the lever of the drive of the pressure regulator; 14 – rubber sleeve of the shock absorber eye; 15 – a cross-section of a floor of a body; 16 – additional buffer stroke compression; 17 – upper longitudinal bar; 18 – bracket for mounting the transverse rod to the body; 19 – bracket for attaching the longitudinal rod to the body; 20 – pressure regulator rear brake mechanisms; 21 – lever drive pressure regulator; 22 – a clip of the basic sleeve of the lever; 23 – supporting sleeve of the lever; 24 – transverse rod; 25 – shock absorber.


The upper and lower rods are tilted relative to each other so that their axes intersect in front of the axle of the wheels, forming an instantaneous center of longitudinal rolling of the suspension, which provides an “anti-peck effect” when braking a car. Shock absorbers are mounted with an inclination inward in the transverse and vertical planes and have some resistance to the relative movement of the axle and the body under the influence of lateral forces.


Installing rear suspension: 1 – body spar; 2 – bracket of the transverse rod; 3 – rear axle beam.

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Author: delfi

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