All of us like to drive cars. But a few of us knows the working of the power steering installed in the cars. Power steering has today become a standard fitment in almost all four-wheelers that we see plying on the roads. It provides easier maneuverability and a better degree of control over the vehicle, which makes driving all the more effort-free.
The term power steering is derived from a ‘power-assisted steering system’. Although electric steering systems have become common in most vehicles today, initially, the basic system for power steering was hydraulic. Today the 80% of the cars on road are equipped with a power steering system which has become the basic need of today’s automobile.
Types of Power Steering System
1. Hydraulic power steering system- It is the type of power steering system in which a hydraulic system having a hydraulic pump driven by the engine and hydraulic cylinders, is used to multiply the steering wheel input force which in turn reduces the efforts required to steer the front wheels of the vehicle. A highly compressed hydraulic fluid is used inside the hydraulic cylinder that applies pressure on the steering gear.
2. Electro-hydraulic power steering system- It is the modified version of the hydraulic system in which the rotary hydraulic pump which is driven by the engine in the hydraulic power steering system is replaced with the hydraulic pump which is driven by the electric motor. It is also called the hybrid power steering system due to the use of both hydraulic and electric components.
3. Electronic power steering system- It is the latest type of power steering system in which the hydraulic system from the hydraulic power steering is completely replaced with electric motors and electric sensors, instead of using hydraulic force, the motor is driven by the vehicle’s battery is used to apply force on the steering gear and torque provided by the motor is controlled by the sensors that detect the position of the steering column. The steering response of this system is quick and very effective which is why it is used in almost all new cars today.
Working of Power Steering System
1- Hydraulic Power Steering System
In this type of power steering system as we discussed above the hydraulic force is used to multiply the steering input force in order to smoothen the steering of the front wheels, this hydraulic force is generated by a series of components that includes a hydraulic cylinder, rotator hydraulic pump, hydraulic lines, highly compressed hydraulic fluid and a coupling mechanism that can couple this hydraulic system with a rack of the steering system.
1- When the driver provides input by rotating the steering wheel, the hydraulic pump driven by the engine starts pumping the highly compressed hydraulic fluid through lines.
2- The hydraulic pressure produced by the pump enters the hydraulic cylinder which in turn applies pressure over the cylinder’s piston.
3- The piston which is under high pressure starts moving from one end to another which in turn pushes the further fluid through lines, with this movement of the piston the input force applied by the driver is multiplied several times.
4- This high-pressure fluid sent by the hydraulic cylinder then applies the pressure to the attached pinion through the coupling mechanism which in turn applies high force to the rack gear and the steering action in the front wheels takes place.
2. Hybrid or Semi Hydraulic Power Steering System
In this type of power steering system, the hydraulic pump driven by the engine from the hydraulic power steering system is replaced with an electric pump which makes it more reliable, this is the only modification made rest the working of this system is the same as the hydraulic power steering system mentioned above.
3. Electric Power Steering System
This system is the latest of all the steering systems mentioned above in this type of steering system as we have already discussed the force multiplication is the function of the electric motor instead of hydraulic fluid and the working of this system is as follows-
1- When the driver gives input through the steering wheel the electronic sensors attached to the steering column read the input and sent them to the electric control unit of the vehicle.
2- The ECU of the vehicle analyses these inputs and sent the voltage signal to the electric motor placed at the end of the steering column whose gear is in constant mesh with the pinion gear.
3- Due to these voltage signals sent by the ECU the motor which is driven by the battery of the vehicle starts and provides the particular torque according to the value of the voltage signals received
4- After the motor starts the gear which is in constant mesh with the pinion gear starts transmitting the multiplied torque to the pinion gear which in turn applies this torque to the rack through which it is attached.
5- With this torque applied by the pinion over rack, rack moves which in turn steer the front wheels (with the help of the tie rods attached) as per the requirement.
For a better understanding of different types of power steering systems watch the video given below