Difference between Power Steering and Electronic Power Steering
Key Difference: Power steering is a system that helps in steering the wheels by using some auxiliary network of power. Electronic power steering is also a power steering system that uses an electric motor and a control unit with some sensors.
Power steering is a system that helps in steering the wheels using some source of power. Steering refers to the mechanism of guiding the wheels towards the intended direction. You must be familiar with the steering systems of cars. The driver uses the steering to control the course taken by wheels. Manual steering is totally different type of steering in which manual force is used for steering. However, today most of the cars have power steering systems.
When we talk about power steering, than we are either referring to hydraulic power steering or electric power steering. Thus, we can say that electronic power steering is a type of power steering and thus has all the features of a power steering. There are two basic steering mechanisms:-
1. Rack and pinion steering- in this system, a pinion gear is attached to the steering shaft which means that as the steering wheel is turned it turns the pinion gear(circular) and then moves the rack (linear). It is basically using the rotational motion of steering wheels and then converting this rotational motion into the linear motion. This linear motion is required to turn the wheels.
2. Recalculating ball steering- in this system, a box is fastened over a worm drive that contains many ball bearings. These ball bearings loop around the worm drive and these balls moves out into a recirculation channel and again gets back into the worm drive. When the steering wheel is turned, the worm drive turns and forces the balls to press against the channel inside the nut. Now this forces the nut to move along the worm drive.
Let us now understand the basic concepts of power steering. Power steering uses hydraulics or fluid pressure in order to help the steering systems. Power steering is preferred when quick turns need to be taken. It reduces the manual efforts applied by the driver.
There are three main power steering components- power steering pump, power steering fluid reservoir, steering gear box. Power steering can be of three types:-
- Hydraulic power steering
- Electronic/Electric power hydraulic steering (EPHS)
- fully electric power steering
Hydraulic power sheerings mainly use hydraulic fluid and the pressure that is generated through this hydraulic fluid helps the driver in steering the wheels. In EPHS, the customary drive belts and pulleys that drive a power steering pump are replaced by a brushless motor. It is driven by an electric motor and thus also reduces the amount of power that needs to be taken from the engine otherwise.
The third category is electric power steering. In this kind of system, an electric motor replaces the hydraulic pump and a fully electric power steering system is established. The electric motor is either attached to the steering rack or to the steering column. The very important component is the electronic control unit that controls the steering dynamics.
Most of the steering systems that are used today are of power steering type. Very few systems use manual steering. EPS are often preferred for the fuel economy and lower emission.
Thus we can say that electronic power steering is not different from the power steering as it falls in the category of power steering. However, there are other kinds of power steering mechanisms apart from the electronic power steering.
Image Courtesy: ClearMechanic.com, allegromicro.com