Steering rack: what it is and how it works
Content
Any car consists of several key systems, without which either its operation is prohibited, or the driver will not succeed. Among such systems is steering. The key component of this system is the steering rack.
Let us consider in more detail its structure, principle of operation, types of amplifiers, as well as some common malfunctions of the mechanism.
The history of the creation of the power steering
The first representatives of four-wheeled vehicles had primitive steering. The swivel wheels were fixed on one beam, which was attached to the body only in the central part on a hinge - according to the principle of horse-drawn transport.
Such a mechanism did not allow self-propelled carts to be maneuverable, and the turning radius was so huge that the car could turn around completely somewhere on the square. In addition, no power steering was required to complete the turn.
Over time, adjustments have been made to the steering system to minimize the steering angle of the car. To make it easier for the driver (each time the invention made the steering wheel turn tighter), various options were developed, ranging from increasing the diameter of the steering wheel itself to introducing different types of gears into the system.
As a result of many years of trial and error, engineers have concluded that the steering rack layout is the golden mean between simplicity, availability and increased torque from the steering wheel. In addition, such a device is compatible with power steering.
Principle of operation
The rack in the machine is presented in the form of a bar with teeth. It is connected to the steering wheel swivel mechanism. It is driven by the steering column shaft using a gear or worm gear.
When the steering wheel is turned, the column gear moves the bar depending on which direction the steering wheel is turned. At the edges of the strip, steering rods are fixed, which in turn are connected to the swivel joint mechanism of each of the steering wheels.
Many modern steering racks are additionally equipped with an amplifier to make steering wheel turn easier. Thanks to the introduction of such a mechanism, comfort and safety in cars has increased.
Device and main components
Most often, a rack and pinion steering modification is used in cars. The device of such a mechanism includes:
- Steering wheel - located in the cab of the car. With its help, the driver sets the direction while the car is moving;
- Steering column - looks like a metal rod through which torque is transmitted from the steering wheel. For safety reasons, this element has one or more cardan joints (in a head-on collision, the steering column folds in several places, which prevents injury to the driver's chest);
- Serrated steering rack. These teeth are engaged by the worm shaft of the steering column. The construction is in a metal case;
- Steering rack rod - rods attached to both ends of the rail with a threaded connection. At the ends of the rods there is a thread onto which the tips with hinges are screwed;
- The steering tips are a hollow tube, on one side of which an internal thread is made (the steering rod is screwed into it), and on the other, a hinge connected to the steering knuckle of the wheel.
Some steering rack modifications are equipped with a damper. It is located between the rack body and the rods. The purpose of this part is to dampen the vibrations coming from the wheels when the car is driven on uneven road surfaces. Most often, this element is installed in the rails of SUVs.
Types and versions
As mentioned earlier, the key elements of the steering rack have not changed for many decades. Only minor adjustments are made to the mechanism, but the principle remains the same.
The only thing that distinguishes all units of this type is the amplifier drive. There are three modifications in total. Let's consider the features of each of them.
Mechanical steering rack
This modification is classic. All cars were equipped with it until the moment when hydraulic and electric amplifiers were created. A mechanical steering rack is the simplest type of device. Thanks to the small teeth and the large steering wheel in comparison with them, the driver does not have to exert much effort to turn the car.
There are steering racks with different gear ratios. A gear transmission with a smaller amplitude is made in the center of the bar, and this indicator increases at the ends. This makes it even easier for the driver to turn the steering wheel when starting off or when cornering at high speed. And in parking lots, when the wheels need to be turned out all the way, the driver does not need to turn the steering wheel many times.
Hydraulic steering rack
This modification differs from the previous one in that its device has an additional mechanism, which is due to hydraulic action. Read more about the principle of operation of the hydraulic booster. here.
The hydraulic booster provides smoothness and at the same time sharpness of response of the steering rack both while driving at different speeds and in a stationary car. This booster also provides more safety when the car is in a rut. In this case, the chances that when hitting an unevenness the steering wheel will pull out of the driver's hands is much less.
Electric steering rack
The electric rail is a similar amplifier. Instead of a hydraulic drive, an electric motor is installed in its design, which enhances the movement of the steering rack.
In budgetary modifications of the electric booster, the motor is in the steering column. The safest option is considered to be with an electric amplifier installed in the rail itself. This modification is included in the package of premium cars.
The first option is the most unsafe, because if the amplifier fails, it will be almost impossible to continue to operate the car.
Compared to a power steering, an electric rail has several advantages:
- Greater efficiency;
- Less vehicle resources are consumed - the working fluid circulates in the power steering constantly, since the pump drive is connected to the crankshaft pulley and is turned off only when the engine is turned off. The electric booster works only when the steering wheel is turned;
- The operation of the mechanism does not depend on the air temperature (it is not necessary to warm up the liquid to increase its fluidity);
- Less attention is needed for maintenance - there is no need to monitor the oil level, as the mechanism works on a different principle;
- The device includes fewer different seals, and there are no hoses, seals that can withstand high pressure. Thanks to this, the mechanism is more reliable than power steering.
The main malfunctions of the steering rack
The following signs indicate a malfunction of the steering rack:
- When driving on a road with poor coverage, a knock appears, which disappears when the steering wheel is turned more;
- Reduction or absence of efforts when turning the steering wheel or in its central position;
- The steering wheel turns itself;
- After turning, the steering wheel tightly returns to its original position or, in general, it must be forcibly turned;
- With a small steering wheel amplitude, the wheels themselves turn much more than before;
- The steering play has increased;
- Increased recoil to the steering wheel when driving over bumps;
- If the car is equipped with a hydraulic booster, fluid flows from under the oil seal, the boot or other elements of the mechanism have oil contamination.
If at least one of the listed symptoms appears, you should immediately diagnose the device and repair it. It is often enough to purchase a repair kit and replace all seals, gaskets and anthers for the device to start working properly.
Here are the most common steering rack breakdowns and repair options:
| Malfunction | How to fix |
| Working out on the bar teeth or in the worm shaft | Recovery of such elements is impossible, so they are replaced with new ones. |
| Breakage of the rack housing | The mechanism is completely replaced |
| Destruction of anthers (dirt and sand gets inside the mechanism, which leads to the development or rusting of metal parts) | Replacing sealing materials from the repair kit |
| Deformation or breakage of tie rods or tips | Damaged parts are replaced |
| The bushing is worn out or broken, causing a play in the steering column | Replacing the bushing |
In addition, the video tells about breakdowns and repair options for steering racks:
Malfunction prevention
The steering rack is a fairly reliable and stable mechanism. Its breakdowns occur most often either due to improper operation of the vehicle, or as a result of non-compliance with the routine maintenance schedule.
To extend the life of this mechanism, you should adhere to simple rules:
- When driving on uneven roads, reduce the speed of the car so that fewer shocks are received in the steering mechanism;
- Leave a parked car with straight wheels;
- Do not turn the steering wheel all the way (if there is a power steering, a squeak or hum from the amplifier pump will be heard), and do not hold it in this position for more than 5 seconds;
- Change the oil in the power steering reservoir in time, control the level of this fluid;
- Periodically make a visual inspection of anthers and seals;
- Warm up the power steering by turning the steering wheel a couple of times in both directions before driving.
The correct operation of the steering rack directly affects the safety while the car is moving, so you cannot ignore the alarms indicating mechanism malfunctions.
Questions and answers:
What is a steering rack? It is the mechanism by which torque is transmitted from the steering wheel to the steering knuckle of the steering wheels. The steering column converts rotary motion into linear motion.
What happens if the steering rack breaks? Steering rack malfunctions lead to excessive steering play, which is fraught with an emergency on the road. With a faulty steering rack, the maneuverability of the machine is lost.
How long does the steering rack go? It depends on its design: what kind of amplifier is in it, what type of transmission is used. Some of them attend to 70-80 thousand, while others work regularly for 150.
