Fig. 13.29. Power steering of the Fiesta car: 1 – reservoir with working fluid; 2 – pump; 3 – pressure switch; 4 – steering wheel; 5 – radiator; 6 – left steering rod; 7 – steering gear with toothed rack; 8 – steering column; 9 – cardan joint; 10 – protective cover; 11 – right steering rod
To reduce the effort required to turn the steering wheel, all Fiestas have been equipped with hydraulic power steering since 1996 (Fig. 13.29). The additional force is provided by high-pressure working fluid, which is supplied to the working cylinders located in the steering gear. The control valve is used to pump fluid into the cylinder under pressure, which corresponds to the angle of rotation of the steering wheel. The control valves operate according to the so-called open-center principle, i.e. when the control valve is not active, the fluid supplied by the pump is bypassed back into the reservoir at zero pressure. The slower you drive, the more the power steering assists in turning the steering wheel; at higher speeds, the steering works practically without the help of the power steering. When parking and maneuvering the car, the power steering works with maximum efficiency; at speeds above approximately 10 km/h, its effect gradually decreases, since at higher speeds the driver expends significantly less effort to control the car.
Repair work with the power steering and its maintenance, right down to the smallest work (checking the tightness of the hydraulic system, topping up the working fluid, etc.), should be entrusted to an auto repair shop.