Steering system

Our Steering Systems Control the Car's Directional Functions and Hold the No. 1 Market Share

The vehicle is provided with basic functions such as running, turning and stopping. The steering system covers one of these basic functions, "turning."
The electric power steering system developed by JTEKT in 1988 first in the world is superior in fuel consumption as well as in the ease of installation and boasts the top share even now.

Steering principles

The driver manipulates the steering wheel, and its rotational movement is converted into a pushing-pulling motion of the tires by the gears, changing the direction of the tires.
In this process, hydraulic and motor power are used to assist the driver and reduce their burden.

Steering System Configuration

Basic steering operation

  • 1

    Steering wheel is turned
  • 2

    Torque sensor detects torque signal,which is then input into the ECU
  • 3

    ECU adds electric current to the motor based on torque signal and vehicle speed

  • 4

    Motor rotating torque is increased by the reduction gear and transmitted to the pinion
  • 5

    Pinion rotating torque (supplemental steering torque) on the power-assist side and pinion rotating torque (steering rotating torque) on the steering-wheel side are converted to rack axial force to change tire direction

System Features by Type


Since the motor and ECU are inside the cabin,waterproofing is not required and there is no influence on engine and transmission layout

Optimum steering system for compact vehicles with small rack force


Excellent steering performance as the result of minimal friction between the time of turning the steering wheel and start of rack movement

Optimum steering system for medium-to large-sized vehicles that require better steering performance

An explanation of the latest technologies

In the near future, transformations will occur not in the vehicle society, but in the way we live as well

Thanks to higher computer processing capabilities and more accurate, inexpensive peripheral recognition sensors such as onboard radar and cameras, modern-day vehicles can detect the periphery and driving conditions with high precision. Accordingly, the practical application of active safety is advancing, perhaps best represented by collision avoidance braking.
Additionally, driver assistance systems openly using EPS control, such as automatic parking systems and lane departure warning/lane-keeping support systems, are contributing to the reduction of traffic accidents and the number of related fatalities. These systems are gradually becoming compulsory and are the focus of NCAP* ratings. As a result, their widespread use is anticipated.
In regards to enhancing Advanced Driver Assistance Systems (ADAS), the potential for further advancements from the current Level 2-3 status to fully autonomous driving systems that take over driver operation may be feasible with the expansion of applicable roads predicted for the future. Such technologies will not only transform the way we drive, but also how we live as well.

* NCAP (New Car Assessment Program)
A public vehicle collision test that involves crashing new cars and assessing the passenger safety level.

The Evolution of Steering Systems

[JFOPS] JTEKT Fail-OPerational System JTEKT concept of safety is defined from 0 to 4.

What is redundancy? By duplicating (making redundant) systems for functions required to have high reliability, safety is secured by the remaining functions even if a component of the system fails (redundant design).

Merits of Steer-by-Wire

・Freedom in communication between the driver and system during ADAS operation(able to freely control both steering wheel and tires)

  • 1.If collision avoidance operation is necessary, not only the steering wheel, but also the tire angle can be controlled appropriately.
  • 2.Changes in vehicle orientation are reflected in steering wheel movement, providing steering sensation.

・Achieving ideal steering properties

1.Improved vehicle response/traceability/stability when changing lanes

2.Improved handling at low speeds, improved driving stability at high speeds

3.Conveys the necessary information from the road surface while blocking out disturbance, thus alleviating driver fatigue

・No-link SBW enables freedom of layout and contributes to expanding the vehicle interior space


Electric power steerings

The steering system supports the driver in turning the steering wheel with an electric power assist unit consisting of a motor, controller, torque sensor and so on, thereby steering the tire.
In comparison with the hydraulic type that uses the engine of the vehicle as a power source, the electric type that uses the battery as a power source can improve the fuel consumption of the vehicle by 3 to 5%.
There are two types: column type with which the power assist unit is located in the column (inside the cabin) and rack type with which it is located in the engine room.

Hydraulic power steerings

The hydraulic power assist unit supports the driver in turning the steering wheel, thereby steering the tire.
The system is compact and superior in the steering performance, capable of issuing a large output.

Unit component

Various components supporting the steering system are introduced.

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Problems or Requests Relating to Car
Repair Products

At JTEKT, we support our customers when they have problems regarding the purchase of car repair products or specification considerations.
Feel free to let JTEKT know about your problems and requests,
whether it’s how to deal with breakdowns or other troubles, or switching over from another company’s product.

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