The steering system or steering is a set of elements that allow you to control the steering wheel of a road vehicle to obtain the change in the direction of the travel. Thanks to the development of the technology that has undergone numerous changes that have improved capabilities ,ensuring greater comfort and safety for the driver.
Steering systems today are divided into three main commands:
The mechanical steering is divided into three other types:
to tie rods,
rack (the most popular system).
Manual steering is itself divided into three other types: to tie rods, a worm screw to rack (the most common system). The mechanical steering rack a linear gear that converts the motion from rotary to linear.
This system despite being very reliable (especially in the case of cars read) is scarcely suitable for heavier cars because they are very hard to operate. For this reason there were created mechanism power-assisted steering systems that constitute a component of the support to the steering rack without however replacing it. This is the electrical components of hydraulic.
The electrical steering power is used mainly for small vehicles or more for vehicles of the economical type. Manually speaking, the mechanical steering box rack is added with a small engine that facilitates the work of steering.
The steering box to a hydraulic steering rack is the most currently system used. The fitting of a hydraulic pump allows the power steering fluid to produce a flow and a pressure acting inside the steering box,making the wheel light and precise, thanks to the power- assisted steering.
Over the years the system has been modified with an addition of the control called Servotronic, which adjusts the steering stiffness depending on the speed supported by the vehicle with the reduction of the impact on fuel consumption.Greater comfort, therefore, with the light steering and maximum agility in the parks and in the maneuvers between the narrow alleys winding roads.
The operation of the hydraulic assisted steering rack. The hydraulically assisted steering is fitted on only some types of vehicles such as tractors, because a response lag and being little fast in the steering is more adapted to the lenses. As a mechanical component that controls the steering and consequently the whole car requires care and skill. Its revision is carried out with the utmost attention, replacing always terminals and gaiters, rectifying the stator and gaskets; is finally subjected to a strict and scrupulous testing with bench testing cycles of pressure hot and cold, using a high- pressure pump that far exceeds the normal requirements of the vehicle.Everything that doesn’t exceeds full marks this procedure is discarded or demolished.
The mechanical steering rack of the hydraulic type has been followed by a new system called EPHS, i.e. the hydraulic pump of the mechanical type has been replaced by a power steering pump electronics.Hydraulically assisted steering pumps.
ELECTRONIC PUMPS HYDROGUIDE SYSTEMS (EPHS)
Electro-hydraulic, EPHS is really an innovative system because it combines the advantages of a steering system on- demand to electronic control with an efficient hydraulic drive. The EPHS is constituted by a unit pump- motor connected to a conventional steering box rack and pinion, this system in addition to ensuring an exact perception of the road by improving alignment of the steering and reducing its noise level, also allows a considerable saving of fuel compared to a conventional hydraulic power- assisted steering up to 0.3L/100km and a reduction of emissions of CO2 about 7g/km.
The EPHS systems able to apply steering effort variable at different driving conditions. The EPHS analyzes the steering angle, vehicle speed, engine speed and control systems of the frame 13 times per second to give a precise sensation of manoeuvrability and the performance of the car. When the car is stationed or travelling at low speeds,the hydraulic pump increases the assistance by reducing steering effort.The pump reduces the assistance at high speed by giving the car a feeling of greater solidity.
The EPS ( acronym for Electric Power Steering), is the electronic power steering system, a component that has appeared in he market of the European car in 1999, for the first time in the Fiat Punto.
The EPS has replaced the hydraulic power assisted steering in the car of small to medium size and is becoming fast the solution most widely used on cars of the segment A, B and C, has the advantage of providing sufficient assistance for loads that is not too high and with some refinements can assist the driver as in the hydraulic assisted steering.
The EPS offers, with respect to the hydraulic steering units, the following advantages:
- Reduction of fuel consumption
- Compact since it is a component of small dimensions complete and is located in the passenger’ compartment, and then easily replaceable
- Absence of piping systems and oils which there slide inside
- Ease of calibration
- Electrical component:
This feature allows to be easily updated and therefore open to new technologies for the future