Today it is rare to find a car that does not have power steering. Years ago, you broke a sweat every time you had to park a car without this system. Fortunately, it's been a long time since has become basic equipment for any model on the market.
The power steering is responsible for reduce the force needed to turn the steering wheel of our car, van, truck, etc. To help us, it has a hydraulic circuit that is responsible for doing the hardest part of the job. Unlike a simple conventional steering system, power steering includes a hydraulic pump that, driven by the crank pulley, circulates the oil through the steering hydraulic circuit.
Power steering parts
- steering column: is the bar and other components responsible for connecting the steering wheel with the rest of the steering mechanism.
- steering pump: is the one that gives life to the power steering. Its function is to move the oil around the circuit so that the driver receives the necessary help to move the steering wheel.
- Control valve: is in charge of distributing the oil as necessary. If the flywheel turns to one side, the valve will take the oil to the indicated side.
- Oil deposit: place where the oil is stored is not necessary to move the direction
- steering control unit: It is in charge of managing the direction based on the force that the driver exerts on the steering wheel, the speed of the vehicle and the position of the wheels. For this, it requires a direction sensor and a direct connection with the control unit, so that they supply the necessary data.
How does a power steering work?
stationary steering wheel
With the engine running, the steering pump is running thanks to the accessory strap o auxiliary strap. That is, it receives kinetic energy in the same way as other elements such as Alternator, Water Pump or the compressor air conditioner.
The first thing the power steering pump does is send oil to control valve, which is normally in the steering column. If the steering wheel does not need to be turned, the control valve does not use the oil it receives and returns it back to the reservoir.
moving the steering wheel
However, if we turn the steering in one direction, the control valve closes the flow of oil to the reservoir, taking it to one side of the cylinder, until it is full. The steering pump continues to send the oil, increasing the pressure in the cylinder, until the piston inside the cylinder moves. The movement of this piston causes the mechanical elements of the steering to move and, consequently, the wheels of our car.
To understand how the valve does this, it is necessary to know that, in addition to the conduit that carries the oil back to the tank, it also has two other conduits whose mission is to transport the oil to the cylinder.
This cylinder is divided into two parts thanks to a mobile piston that is inside it, which in turn joins the mechanical steering system. If the cylinder is filled on one side, it moves the piston to the other, facilitating the steering movement. If it is filled by the other, it will do the same in the opposite direction.
When you stop moving the steering wheel
When the flywheel stops turning, the control valve no longer sends oil to the cylinder, so the piston stops moving. Now the control valve forces the oil to be sent back to the tank.
If you turn the steering wheel in the other direction, the process is exactly the same, with the particularity that the piston moves in the opposite direction.
Types of power steering
Normally, it is usual to talk about the types of address without making a previous distinction. However, the assisted directions They can be classified according to their type of actuation and according to the design of the mechanism. of the steering box. Here is a description of each of them:
Depending on the type of drive
This means, the method which is used for the address to give driver assistance:
- Hydraulics: uses a hydraulic pump connected to the motor by a set of pulleys
- electrohydraulic: It also uses a hydraulic pump, but this is powered by an electric motor.
- Electrical: the electric motor is used directly to assist the steering
According to the design of the steering box
This distinction refers to the shape of the mechanism to move the wheels Finally:
- Rack and pinion: the steering has a helical pinion at the end that, when turning, moves a rack bar (with grooves) to one side or the other
- Endless screw: what moves the steering is a worm gear that turns the steering roller
How to change a normal power steering to variable power steering? And to electric. It is for my 3 BMW Z97 which is very soft at a speed of 90 km/h. Thank you.