Why to equip vehicles with power steering?

In the list of equipment options for modern cars, there is often a mechanism that has the name – power steering. It is indicated as GUR or as – EPS.

How does a GUR and an EPS work together?

Hydraulic power steering began to be used much earlier than electric power steering. The power steering system functions using a fluid drive, it has a hydraulic pump that is driven by the crankshaft through a belt drive. When the vehicle is travelling straight ahead, the exchange of fluids is circular. When the trajectory changes (when the steering wheel is turned), the fluid enters the inner cavities of the distribution sleeve. Then it will enter the left or right cavity, according to where the steering wheel is turned. This is how the piston moves the elements of the rack. The forces during the turns are transferred to the rods, changing the direction of the car. The pump will be more productive when the steering wheel is turned on the spot (parking). The system is driven by a belt drive from the crankshaft, but its revolutions during parking are minimal. It becomes clear that the effort produced by the pump is not enough to turn the steering wheel. The manufacturers have taken this point into account. Under these conditions, the ECU will signal for additional opening of the valves. More fluid will enter the rack cylinder and when parking the steering wheel will, accordingly, be easier to turn. But the driver must remember that the pump will be operating at full capacity and frequent turning of the steering wheel to the extreme position can reduce the life of its work.

The manufacturers started to use EPS much later, but this mechanism gained huge popularity quite quickly. The main difference between EPS and GPS is that there is no belt drive in the design, and there is no hydraulic drive. Manipulation is carried out by an electric motor.

There are two types of EPS layout. The first option – the force of the electric motor is transmitted to the rack, the second option – to the steering shaft. The first variant – the most frequently used, it still has another name – electromechanical. The type of electric motor used is called asynchronous. Torque is transmitted to the rack from the electric motor. The EPS is equipped with many sensors, which are interconnected with the ABS and ECU. The information from the sensors is processed and then the signal is sent to the executing device, which is the asynchronous motor.

Which to choose – power steering or electric power steering? 

The two mechanisms have their own advantages and disadvantages.

The GUR – is an inexpensive mechanism, so the price of the car will be lower. When a GUR repair is needed, it won't be expensive either (if the rack is working). On the downside – the size of the structure itself. GUR is massive, it needs a lot of space. There may be difficulties in repairing the timing belt. To replace the belt, you will need to remove the pulley from the PTO.

When choosing between the – GUR or EPS options, consider how future maintenance will be carried out. A power steering system requires a systematic system of maintenance. You'll need to replace the fluid and belt in time, and if you don't – you can't avoid repairing the booster. The mechanism may also require repair if it is operated in overload mode. The work of the node is very dependent on the power of the motor, GUR can reduce its performance. Today, the power steering system is predominantly used in off-road and commercial vehicles.

The EPS has more advantages than disadvantages. It doesn't take power from the engine. The system won't require regular maintenance because the fluid and pumps aren't built in. The rolling bearing may fail, but it will take quite a long time of use to break it. The response to the steering wheel is faster, signals from the sensors are transmitted instantly. EPS occupies a minimum of space under the bonnet, which facilitates repair of other units. There is no pump overload when the steering wheel is held in the extreme mode for long periods of time.

Summarise. When your vehicle – passenger car or crossover, it is better to choose EPS. On heavier vehicles, an EPS will be the way to go.