Comparison of different in design, but identical in purpose, vehicle components is a normal phenomenon. HPS or EPS in this regard is far from the only example. Automatic or mechanical, xenon or LED, GEL or AGM batteries. At their core, these pairs are one and the same. They were just invented at different times and made using different technologies. It is quite natural that such things have always been compared. Power steering did not go unnoticed.
15 criteria for comparing HPS with EPS
It is best to compare something according to certain criteria. The more of them, the more objective the results can be considered. In the case of the electric booster and the hydraulic booster, after some thought of the criteria, 15 pieces were found:
- Subjective feelings.
- Design features.
- Device complexity.
- Machine price.
- Service complexity.
- Repair cost.
- Steering response.
- Wheel feedback.
- Amplifier type and fuel consumption.
- Dimensions and weight.
- Problems in the winter season.
- Combination with "smart" car electronics.
On such points, for example, as design features and combination with "smart" electronics, there is a whole abyss between the hydraulic power steering and the EPS. There are also those for which the difference is very blurred and not always unambiguous. For example, it is difficult to say with certainty that cars with hydraulic boosters are more expensive than those with electric boosters. Nevertheless, a certain regularity is observed for absolutely each of the presented criteria. And this means that they are all worth considering.
No matter how chaotic it may look, but an objective opinion always consists of several subjective ones. Moreover, the first has always been considered more valuable than the second. In the case of clarifying the question of which is better - hydraulic boosters or electric power steering - everything is simple. You should definitely try both. Without this, re-read at least a hundred articles on the topic - you won’t really understand anything. It's like trying to judge the taste of two coffees by reading their descriptions on the packages.
The only benefit of these types of materials is that they help you understand what to look for. That is, if you drive two cars with different hydraulic power steering systems without preparation, the conclusions will be inferior. A similar comparison, but with the proposed list of criteria, will allow you to see things that are not quite obvious more clearly.
It is impossible to say something more concrete on this point, as it will be biased. For example, the author of the material prefers the classic hydraulic power steering. There are several reasons. Among them, pure chance - the machines of the desired model with the EPS simply never came across. But this cannot mean in any way that hydraulics are objectively better than electronics. One criterion and opinion is not enough. Move on.
Design features and complexity of the device
These criteria should be combined, since the complexity of the device becomes more or less clear immediately after analyzing the design features. Looking ahead, we note for ourselves that there are still more cars with hydraulic boosters than with electric boosters. Therefore, classical hydraulics will be considered first.
Hydraulic power steering structure
The whole essence of the mechanism is as follows. The hydraulic booster "understands" when and in which direction the driver turns the steering wheel, and, depending on this, helps to turn the front wheels. The force that is used to do work is a fluid under high pressure. It is created by means of a pump. The latter is constantly powered by the engine.
First you need to figure out how the system “pushes” the wheels in the right direction. This is done by a hydraulic steering rack. Its main part is a hydraulic cylinder. It has a piston that divides the cylinder into two sealed compartments. Physically, it is fixed on a rail, which pushes the wheels to one side and the other through the rods and steering tips. If you apply a working fluid under high pressure to one of these compartments, the piston will begin to move. So, the hydraulic power steering "helps" the driver to turn the wheels.
Let's briefly analyze how the hydraulic power steering "understands" - when and in which direction the driver turns the steering wheel. After all, it depends on which of the two compartments the working fluid will be supplied to. As long as the car is driving straight ahead, the oil in the booster system circulates idly. That is, it is distilled from empty to empty. As soon as the steering wheel begins to rotate, the working fluid under pressure rushes into the hydraulic steering rack. Responsible for this node, which is called the distributor.
The distributor is perhaps the most complex part of the hydraulic power steering. They come in different designs, and there is not much point in describing them here. We have a different goal. As a result, it turns out that the hydraulic booster has a rather complex device. But don't jump to conclusions. Let's now look at the EUR.
In the minimum version, the electric power steering consists of three components - an electric motor, a steering wheel rotation sensor and a controller. It seems to be simple and clear. The sensor "monitors" whether the steering wheel is spinning, and in which direction. If yes, then the corresponding set of signals is transmitted to the controller. That, in turn, gives commands to the electric motor - in which direction to rotate and with what force. Well, the engine itself is physically connected to the steering and front wheels.
If you look at the electric booster from this point of view, then this technology may seem an order of magnitude simpler than hydraulics. However, this is not quite true. The same controller seemed simple, because for an uncomprehending person it is just some kind of box with electronic components. Have you ever tried to figure out how electronics work? If you go deeper, then it is much more complicated than hydraulics.
As a result, we have the following. Visually, the hydraulic power steering seems to be a more complex unit than the EPS. Including because the electric power steering looks more compact and in them the whole essence is hidden inside. If you look at these two technologies from the point of view of repair, the conclusions about which is better will no longer be so unambiguous. But let's talk about repairs.
This item often refers to the disadvantages of hydraulic boosters. And all because more materials are required for the manufacture of hydraulic power steering. Strict requirements are also imposed on their strength, since there is high pressure inside. EPS is relatively cheaper for manufacturers. But how much?
If a car with electric power steering costs, say, half a million no matter how much money, then with a hydraulic power steering its price will be higher by a couple of thousand. In fairness, it should be said that such a pattern is not always observed. And the difference of a couple of thousand against the background of half a million looks, to tell the truth, ridiculous. At least not seriously enough to confidently state by this criterion that the EPS is better than the hydraulic power steering.
In terms of reliability, the opinion of the majority is often influenced by some subjective assessments. For example, someone bought a car with an EPS, which failed in the first year of operation. It is clear that this car owner will foam at the mouth to prove that the electric amplifier is an extremely unreliable junk. But does this mean that hydraulic power steering is objectively more reliable? Not at all.
After all, it doesn't have to happen once in a while. Someone and hydraulic boosters often fail. And they all flow, buzz, become a source of steering wheel vibration, and so on. Others do not even know what type of amplifier they have in their car. It just works and doesn't cause problems for many years.
In general, if you spend half an hour walking through car forums, you can see that real motorists write about breakdowns in the EUR more often. Accordingly, because of this, it seems that hydraulic power steering is a more reliable and trouble-free technology. In fact, it cannot be said. There are weaknesses here and there. A lot also depends on the make and model of the car. Somewhere more successful designs are used, albeit obsolete. On other cars, on the contrary, new technologies, but still requiring serious improvement.
Bottom line — theoretically, hydraulic power steering is better than the EPS in terms of reliability. But with a lot of reservations and clarifications.
Anyone who has owned hydraulic power steering machines knows the maintenance they need. It is necessary to monitor the level of the working fluid. Top it up in a timely manner. There are dust caps on the steering rack. If they are cracked or, God forbid, torn, the hydraulic cylinder with the piston is kapets. Other steering parts also need to be monitored, since hydraulics can easily suffer due to dead tips or rods. In general, boring technology — hydraulic power steering.
With electric power steering, at first glance, much easier. What is worth only that there is no liquid. However, one should not flatter oneself and relax. The EPS also has details that require periodic attention from the car owner. Including, like other electronics, the system needs to ensure good contacts, protection from moisture and regular elimination of oxides. Very often, they don’t follow all this, but then they generate their complaints and complaints on the forums that the EPS is a synonym for unreliability.
Bottom line — hydraulic power steering is a little more difficult to maintain. The fluid, even if it does not leak, needs to be replaced periodically. Anthers and more. The EPS, if successfully done, requires attention only occasionally. And there are also those who, without any maintenance, thresh for years without fail.
According to this criterion, the EPS is more often praised, which is unfair. Yes. Certainly. If you don’t follow the hydraulic power steering, make it work for a long time with an insufficient fluid level and torn anthers, the repair will cost a pretty penny. However, if the car owner maintains the hydraulic power steering system in a timely manner, then it can serve without breakdowns almost forever. It is also worth adding such an important factor as the multicomponent node. That is, due to the fact that the power steering consists of many individual parts, their replacement is usually not expensive.
As for the EPS, in most cases the system is a block node. Accordingly, if something breaks, the whole block must be changed. And this is completely different money. In this case, everything is expensive - both the electric motor and the controller. Of course, you can repair these parts yourself. But this is much more difficult than changing the fluid, cracked anthers or damaged pipes. Again, due to the greater prevalence of hydraulic power steering, parts are easier to find. In particular, on the same showdowns.
Bottom line - repairing the EPS is usually more expensive, since the system has a block structure. The hydraulic power steering hits the pocket only for those who do not follow it for a long time, drive without fluid or with damaged anthers. But, again, not every time. This must also be taken into account.
Steering response and feedback
Again, we combine the two criteria into a heap, since it makes little sense to consider them separately. Moreover, on this point, the hydraulic power steering is clearly better than the EPS. The hydraulic power steering is more responsive, informative and understandable. Driving a car with electric power often takes some getting used to. Some people still can't do it, abandoning this technology, if not forever, then for a long time.
The feeling of driving a car is often also dragged into this. Most say that they are nicer with hydraulic power steering than with EPS. Whether this is so, it is impossible to prove with words. Need to try. In addition, the so-called "cottoniness" of the electric power steering is not felt on all cars. And on the most modern, the system is also adjustable, which allows you to adjust the sensitivity, responsiveness and feedback to personal preferences.
Bottom line - electric power steering is not yet on all machines please their owners according to this criterion. Hydraulics in this regard is difficult to beat, if not impossible.
Type of booster and fuel consumption
A lot of “experts” have divorced on this subject on the Internet, who in all seriousness claim that a car with a hydraulic power steering consumes more fuel than with an EPS. They justify this by the fact that the hydraulic booster pump constantly rotates, taking energy from the engine. And that's extra fuel. The electric motor of the EPS rotates only when the driver turns the steering wheel. Accordingly, only at these moments it eats fuel, which is spent on generating electricity by the generator.
In theory, everything is clear and logical. But there are three "buts" at once. Firstly, no one has ever measured in practice how much fuel is spent specifically on the operation of the hydraulic power steering or the EPS. Secondly, in the case of hydraulics, although the pump rotates constantly, when the steering wheel does not turn, it does it idle. Thirdly, without experiments it is impossible to say how much the generator loads the electric motor during operation. But for a second, the hydraulic power of the EPS motor varies from 1 kW and above. This is comparable to a starter. And we hope everyone knows how powerful this consumer is.
Bottom line - the imaginary efficiency of cars with EPS is nothing but an unverified myth. This fiction is used by car dealers, and “experts” from sofas, and others who benefit from presenting electric amplifiers in the best possible light. It has nothing to do with objectivity.
Dimensions and weight
If we consider a more compact and lightweight advantage, then according to this criterion, an electric booster is better than a hydraulic booster. On the other hand, who cares how big or heavy the car assembly is, if the difference against the background of one and a half tons is a few miserable centimeters with kilograms. It is not necessary to carry a hydraulic power steering in your hands. Under the hood, it occupies exactly as much space as the designers have allocated for it.
Outcome. In the question of which is better - power steering or EPS - size and weight have no practical significance. For the same constructors, yes, this is important. But we, as car owners, do not care.
Problems in the winter
Everything here is extremely simple, and therefore short. Where there is liquid and rubber parts, there are always problems associated with negative temperatures. The oil thickens in the cold season, it takes time to warm up, and until it does, it will not work effectively. Rubber anthers, oil seals and seals tan and wear out in the cold. There is none of this in the EPS. Which means there are no problems. True, only when it comes to winter.
On this point, electronics will never bypass hydraulics. Not because it is impossible to create a powerful electric motor. More as possible. But these are not childish dimensions and weight. And most importantly, food. The power of the generator is limited, and is spent far from only hydraulic power steering. This is exactly what, by and large, is the most serious brake that does not allow engineers to make the EPS at least as close in power to the hydraulic power steering.
Outcome is obvious. On the other hand, it cannot be said that drivers in passenger cars experience discomfort because of this. Efforts are enough that there, that there. Here trucks and heavy special equipment have such a problem. Because their hydraulic power steering is still indispensable.
Combinations with "smart" car electronics
Here, too, almost everything is obvious, and does not require detailed explanations. The electrical assembly is much easier to combine with "smart" electronics than the hydraulic one. Thanks to this, cars appeared that can park on their own, drive without a driver, guided by road markings, and so on. Also because of this factor, many believe that the EPS is the future. May be so. Such a future, by the way, has already arrived, but only for 1% of the population of the planet Earth.
This criterion is the last one on our list. In life, he is almost the first. In order to objectively compare the EPS with the hydraulic power steering for safety, let's draw in mind for both technologies the result of a system failure. When the hydraulic booster stops working while driving, the car can continue to be driven. Yes. The steering wheel will be harder to turn than usual. But to direct the car to the right place, the opportunity remains.
If the EPS fails, this opportunity is not always provided to the driver. In life, there were electronic glitches, because of which the car not only lost control, but simply went where the enraged electric power steering orders it. Fortunately, such cases are rare. However, this is enough to consider hydraulic power steering safer.
As a result, you learned, albeit in general terms, what is the difference between a hydraulic booster and an electric power steering. What are the advantages and disadvantages of both technologies. Weaknesses and strengths, prospects, myths and unsubstantiated inventions of couch "experts" are also now known. To the question of which is better – hydraulic power steering or EPS, the answer will come by itself when you try both options in practice.