Its been a long time I have been thinking to write this article about the two most commonly used power steering technologies, viz. Electric Power Steering and Hydraulic Power Steering. Before i tell you the difference, lets talk a few words on the basics.
What is power steering?
Power steering is a system which helps to steer the wheels with some source of power other than the drivers manual force with which he turns the steering. This feature adds to the comfort while driving as less effort is needed to turn the steering by the driver. Power Steering is specially important for the cars which have engine in front and there is a lot of weight on the front wheels.
For rear engine cars like Tata Nano or light weight cars like Maruti 800, its ok to have no power steering and still drive comfortably because of low weight on the front wheels. But for heavy cars and also as a luxury feature power steering provides lots of ease.
Hydraulic Power Steering
Hydraulic power steering uses high pressure fluids for assisting the steering movement. It uses a plunger type arrangement for its working. When the driver turns the steering wheel, it opens up the flow or pressurized fluid in such a way that helps to turns the wheels in the required direction.
Electric Power Steering
Electric power steering works with the help of an Electric Motor and a control unit which has some sensors. The motor runs on battery and will use electric power to assist the movement of steering when the driver turns the wheel.
Hydraulic Power Steering V/S Electric Power Steering
Hydraulic power steering is a primitive technology used for decades and has improved a lot with time. Earlier, it did not have any difference in steering response with speed of the car, but the new age of hydraulic power steering are speed sensitive and work better than the older hydraulic power steering.
Electric power steering are comparatively new technology with less complicated build and mechanism, takes less space and are more durable. Electric power steering use sensors to sense the car speed and will take care of the different steering response required for different speeds.
Some of the main differences are as below:
1. Hydraulic Power Steering System is complicated compared with Electric Power Steering
2. Hydraulic Power Steering System usually weighs more than Electric Power Steering
3. Hydraulic Power Steering uses hydraulic fluids for operation whereas there is no such fluid needed for Electric Power Steering, thus Electric Power Steering needs less maintenance compared to hydraulic power steering.
4. Electric Power Steering gives better response at different speeds as compared to Hydraulic Power Steering
5. Eclectic Power Steering is less prone to problems and faults and are more durable as compared to Hydraulic power steering.
6. Hydraulic power steering extracts power from engine, so it reduces the fuel mileage of the engine. Electric power steering consumes power from battery which is also charged by engine, but it consumes less power compared to Hydraulic power steering. So a car having Electric power steering will give more mileage than one with Hydraulic power steering.
Conclusion :
Electric Power Steering is better than Hydraulic Power steering. Hope this helps you decide when you look into the features of the car you are going to buy. For instance, comparing Hyundai Santro and Hyundai i10 , Hyundai Santro has Hydraulic Power Steering whereas Hyundai i10 has electric power steering.
Updated 21 July 2010
Nissan has just revealed a more efficient innovative mix of the above two technologies - Electro Hydraulic Power Steering System By Nissan
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Your article, while technically accurate, doesn’t make any effort to draw the line between these two technologies and articulate where one is better than the other. Electric steering has advantages in small passenger cars, but it is not feasible in larger vehicles and is certainly not currently possible with commercial vehicles(Class 6/7/8 trucks & buses). This article makes it sound like it’s appropriate everywhere and should be on everything we drive–not true.
It would be appropriate to target the article to a specific continent. For example, in Europe it’s all about small cars(crowded roads, small parking spaces), but here in the United States where we drive larger passenger vehicles…it may be marginal and cost prohibitive to use/consider electric power-steering.
Articles like this, that are so greatly one dimensional, do little to advance the general understanding of a reader who wants to understand a new technology and where it applies.
With few exceptions, EPS cars offer poor performance in terms of responsiveness, feedback and steering weight.
Compare a BMW 1-series coupe with electric steering against a 1-series hatchback with conventional hydraulic PS. The coupe is nothing like as wieldy as the hatch.
The best example of EPS so far is on the Mazda RX-8.
Other manufacturers may catch up but given that EPS first came out in the early ’90s in the HOnda NSX, don’t hold out any hopes.
@ray
thanks for sharing your experience and point of view, you have increased my knowledge by sharing this information.
Hi ray, i have a RX-8 which have intermittent fault on the EPS…sometime it become normal without touching anything but only restart the engine, you have solution for this??thanks
@wei
i got my electric power steering replaced 2 days back when it failed abruptly. It was really annoying to run the car without power steering. It was covered under my car’s warranty, so i didn’t have to pay for it, else it could have been a big hole in my pocket to get it replaced. The failure was because of some malfunctioning sensors or motor !
It is good to read about power and electric steering.
Excellent explanation with clear comparison! I’m a newbie to automobile world and this article helped me to understand EPS & HPS. Thank you
its helped e me morwhile i m giving poster presentation in my college[aec]
Quote Hydraulic power steering is a primitive technology Unquote.
I wish the article, although informative, was more balanced. Both power steering systems has its advantages and disadvantages. For eg. Electric PSS as of now can only be used in small cars due to the limitation of the size of the servo motor due to the power of the battery. ( I dont know how is this in the hybrid cars). All the large cars and the larger vehicles all have Hydraulic powered steering systems due to this reason.
Anyone who reads the article will be biased to form and opinion that Electric PSS are superior in all respects to Hydraulic PSS which is wrong.
EPS can have a high failure rate, leaving a vehicle unsteerable. Google search Chevy Cobalt Electronic Power Steering….
hi… the information provided by you is very useful for the newbie like me….atleast admin has added some base knowledge about PSS nd hydraulic steering system… the rest of the research will be easy for us…..thanks admin…
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hi,the information provided by you is very useful.Thanks
can i replace hydraulic powersteering of santro to EPS of i10.. please advice cost .. i stay in bangalore
@Amit I don’t think u can do that so easy. These components are designed as per the car assembly design and can’t be replaced just like that. I recommend that u don’t attempt that, rest your wish ! Do let me know in case u replace it, i am curious.
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pls explain design parameters for electric power steering & its cost
@lovepreet
i don’t have design parameters details. If you are interested in it, contact some steering system manufacturer.
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I test drove many cars and SUV’s over the past few months. I came to the conclusion that I will not buy a car with Electric Power Steering. The steering feedback is universally crap! Power assist is non-linear and nearly unpredictable in EPS systems. EPS leaves the driver feeling less in control of the car. Worst of all every one of the cars I test drove with EPS required nearly constant course correction on the highway, whereas hydraulic systems seem to self correct naturally on the highway.
Exiting corners is far better with hydraulic steering and steering while changing speeds is far more predictable and secure with hydraulic.
My conclusion is that EPS is a cost saving measure resulting in a poor quality driving experience. The technology is not ready for prime time and I will not consider a car with EPS for several more years.
@Etienne
Thanks for sharing the insight.
You’re welcome Rohit,
I forgot to mention one other anoying aspect of EPS systems:
There is a slight “sticky” feeling about some EPS systems when steering “on-center” on the highway. It is difficult to describe this subtle, yet disturbing, sensation. The steering feels like it sticks slightly when on-centre, and then moves freely once the driver applies sufficient force to overcome this slightly “stuck” feeling. It is not a smooth transition from on-centre to lane change/correction steer. The worst vehicle for this effect that I drove was the Ford Escape (2010).
It is a subtle feeling (except in the Escape it is quite obvious), but I find it disturbing for long highway trips. This effect is totally absent in hydraulic power steering vehicles. Hydraulic provides a smooth, consistent, predictable steering feedback under all normal steering conditions.
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Fantastic explanation between EPS Vs HPS.
It has helped me a lot to purchase Next Gen i10
Thank Q
I want know someone told me after certain speed electric power steering stop working. Is it true? If yes please explain me
i purchased a verna petrol car which has a hydraulic powered steering system. I presume reading the articles that it is by choice since it is a bigger car compared to i10. Is the system speed sensitive
Its a very good explanation on steering systems
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@rudresh: Beyond a certain speed, you don’t need power steering, but it does not cut-off, at least not completely. If you steer more than a certain amount, the power steering kicks in and helps you with the steering.
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After long years on my C180 Sportcoupe with hydraulic steering; it was a non-pleasant surprise to drive an EPS car, namely Hyundai Elantra ’11. On highways you have to constantly correct the steering just to go straight. The steer has a tendency to stay on the neutral position and you have to apply a force to overcome this.
I will definitely need some mileage to get used to this EPS steering thingy.
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