S-class W202 Mercedes

1993-2000 of release

Repair and car operation

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

As a result of these reflections in the XIX century the concept of the amplifier of a steering was born. After emergence on streets of the cities of supersize buses with the steam engine it became necessary to facilitate work of drivers operating them. Began search of the constructive decisions, allowing to reduce effort at turn of a steering wheel.

In 1925 in the USA Frances Deyvis one of the first was patented by the hydraulic amplifier of a steering, and in 1933 the concern "General Motors" already intended to establish it on the Cadillac car with the dvenadtsatitsilindrovy engine. By 1951 the Kraysler company mastered production of power steerings and from now on started to equip with it many models. The Fiat firm was the first manufacturer of the cars who has offered installation of the hydraulic booster of a steering as the additional equipment of model "519". 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 a steering even on small cars. As appears from the name, this device is based on use of a principle of hydraulics. Pressure in the system filled with special liquid, is created by the hydraulic pump put in action by the crankshaft of the engine. In a design the zolotnikovy valve which at turn of a wheel switches supply of liquid in this or that cavity is provided, providing additional impact on the executive mechanism of a 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 the steering informativnost was lost. Such systems were established on the car up to the 80th years. Easy to itself to present, 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 should correspond the mechanism of the hydraulic booster follow. The task consists in making a povorachivaniye easy when maneuvering with small speed and more notable on effort on a steering wheel at movement with greater speed that driving became safer.

At the majority of hydraulic boosters regardless of speed of movement of the car the factor of strengthening remains to constants. However the increasing number of cars arriving on the market is equipped today with systems with variable factor of strengthening at which extent of strengthening already changes depending on speed of movement of the car. They provide exact and fast reaction at car movement on turns and demanded effort when maneuvering car with 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 movement in the direct direction, transfer number of the steering mechanism equal to unit and factor of strengthening the smallest, but in process of approach of a steering wheel to its extreme provisions, the transfer number increases also the effort necessary for a povorachivaniye of wheels, decreases. The hydraulic booster of the steering mechanism operated by the computer, also ceases to be something unusual. Such systems of a steering process information from a car speedometer. Their work is defined not only number of turns of the engine, but also speed of movement of the car. The microprocessor of the computer analyzes signals arriving from the sensor and calculates factor of strengthening demanded on every moment which is realized by means of the electrohydraulic converter.

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