Mercedes of the S-class W202

1993-2000 of release

Repair and operation of the car

The person always aspires at a minimum of the spent efforts to receive a return maximum. At first to it began to go laziness on foot – and the car appeared. Shortly the "hardworking" mankind with horror found out that even on twisting a wheel, forces it is necessary to spend not so a little. Also thought, as if the heavy fate to facilitate...

As a result of these reflections in the 19th century the concept of the amplifier of steering was born. After emergence on streets of the cities of heavy-load buses with the steam engine it became necessary to facilitate work of the drivers operating them. Search of the constructive decisions allowing to reduce effort at turn of a steering wheel began.

In 1925 in the USA Francis Deyvis one of the first patented the hydraulic amplifier of steering, and in 1933 the General Motors concern already intended to establish it on the Cadillac car with the twelve-cylinder engine. By 1951 the Chrysler company mastered production of power steerings and from now on began to equip with it many models. Fiat was the first manufacturer of cars who offered installation of the hydraulic booster of steering as the additional equipment of the 519 model. Now as a result of emergence of front-wheel cars, use of tires of the bigger size and weight, a suspension bracket with the complicated kinematics there is a need for use of amplifiers of steering even on small cars. As appears from the name, this device is based on use of the principle of hydraulics. Pressure in the system filled with special liquid is created by the hydraulic pump put in action by the engine crankshaft. The spool-type valve which at turn of a wheel switches supply of liquid to this or that cavity is provided in a design, providing additional impact on the executive mechanism of steering (a reducer or a lath). Originally steering designs with the hydraulic booster were imperfect and had a number of shortcomings. For example, they reduced effort when driving so that informational content of steering was lost. Such systems were installed on the car up to the 80th years. It is easy to imagine, how dangerously "to go too far" at a manipulation a wheel, carrying out turn at great speed.

From here the main requirements to which there has to correspond the mechanism of the hydraulic booster follow. The task consists in making turning easy when maneuvering with a small speed and more notable on effort on a steering wheel at the movement with greater speed that driving became safer.

At the majority of hydraulic boosters regardless of the speed of the movement of the car the coefficient of strengthening remains to constants. However the increasing number of the cars coming to the market is equipped with systems today with variable coefficient of strengthening at which extent of strengthening already changes depending on the speed of the movement of the car. They provide exact and bystry reaction at the movement of the car on turns and the required effort when maneuvering the car with a small speed.

One of ways of achievement of it is use of a lath of the steering mechanism with the variable relation of gear gearing. For this purpose on length of a lath the step and diameter of a delitelny circle of teeths changes, and on a gear wheel the step of teeths remains to constants. When wheels of the car are exposed for the movement in the direct direction, transfer number of the steering mechanism equal to unit and strengthening coefficient the smallest, but in process of approach of a steering wheel to its extreme provisions, the transfer number increases also the effort necessary for turning of wheels decreases. The hydraulic booster of the steering mechanism operated by the computer also stops being something unusual. Such systems of steering process information from a car speedometer. Their work is defined not only by the speed of the engine, but also speed of the movement of the car. The microprocessor of the computer analyzes the signals arriving from the sensor and calculates strengthening coefficient demanded for every moment which is implemented by means of the electrohydraulic converter.

Idea of developers of such systems: to take the best of two types of steering – at the speeds characteristic of a car parkovaniye, to make steering the easiest, and at the movement with a high speed to reduce operation of the amplifier to such an extent that the system worked almost the same as usual mechanical steering without amplifier.