Drivers are often faced with the need to describe malfunctions or operating features of their car, but do not always know the exact terminology. When it comes to how exactly steering wheel rotation translates into wheel motion, many technical names come to mind. However, the correct answer to the question, what is the name of the device designed to transfer force to the steering wheel (or rather, from the steering wheel to the wheels) is steering gear. It is this node that serves as the link between the driver and the road.
Understanding the operating principles of this unit is critical for every vehicle owner. Not only driving comfort, but also the safety of all road users depends on its serviceability. Modern engineering uses several basic types of structures, each with its own unique characteristics and maintenance requirements. Let us examine in detail what this unit is and how it functions under various operating conditions.
Main purpose and principle of operation
The main function it performs steering gear, consists in converting the rotational movement of the steering wheel into the translational movement of the rods. This allows you to change the angle of rotation of the steered wheels with minimal effort on the part of the driver. Without this device, driving a heavy car would be almost impossible, since direct connection of the steering wheel to the wheels would require enormous physical strength.
The operation is based on the principle of changing the gear ratio. This means that a small turn of the steering wheel on the input leads to a significant movement of the rods on the output. Modern systems are often supplemented hydraulic booster or electric booster, which reduce the load on the driver’s hands, especially when parking or driving at low speeds. However, the mechanical part itself has remained unchanged in its essence for many decades.
It is important to note that the device must have some feedback. The driver must feel the resistance of the road in order to understand the grip of the wheels on the surface. Excessive ease of control can be dangerous because it creates the illusion of complete control, whereas on slippery roads it can lead to loss of control. Therefore, engineers carefully balance the force required to turn.
⚠️ Attention: Any extraneous knocks or increased free play of the steering wheel indicate wear (wear) of the internal components of the mechanism. Ignoring these symptoms may result in complete failure of the control system while driving.
The key element here is torque transmission. Depending on the type of design, this may occur through a worm pair, a rack or a screw mechanism. Each of these options has its own advantages in terms of reliability and compactness. The choice of a specific type depends on the class of the car and its intended purpose.
Types of steering mechanisms in modern automotive industry
There are two main types of designs that dominate the automotive industry today. The first and most common for passenger cars is rack and pinion mechanism. It is characterized by simplicity of design, high accuracy and compactness. Inside such a unit there is a gear, which, when the steering wheel is turned, moves the rack to the left or right, pushing the rods.
The second popular option is worm gear. It is more common on old school trucks and SUVs. Here the force is transmitted through the worm and the sector. The main advantage of such a system is the ability to obtain a large gear ratio, which allows you to control very heavy machines without powerful amplifiers. However, worm gears have a significant drawback - they are less accurate and have more backlash compared to their rack-and-pinion counterparts.
There are also more complex options, such as globoidal-worm or screw mechanisms, but they are used less frequently and in specific conditions. For example, some models use combination systems to achieve the ideal balance between force and reaction speed. The choice of type directly affects the driving behavior and feel of the car.
It is worth mentioning systems with variable gear ratios. In such designs, the pitch of the rack teeth varies from the center to the edges. This allows you to maintain sharp reactions at small turning angles and reduce sensitivity at large angles, for example, when parking. This technology makes control more predictable and safer in emergency situations.
Design features and key components
Understanding how the force transmission device works, one cannot fail to mention its components. The basis is the housing in which the working elements are located. Rack and pinion mechanisms are characterized by the presence of the rack, which slides inside the housing. At the ends of the rack there are lugs that connect it to the steering knuckles of the wheels through the steering rods.
In systems with hydraulic booster (power steering), a pressure distributor and a piston are connected to the mechanism. The pressurized fluid helps move the rack, making the driver's job easier. In electrical systems (ES), an electric motor is installed on the steering column shaft or on the rack itself, which creates additional force based on a signal from the electronic control unit.
- 🔧 Carter - durable housing that protects internal parts from dirt and water.
- ⚙️ Input shaft — connects to the steering column and transmits rotation from the steering wheel.
- 🔗 Steering rods - rods that transmit linear motion from the mechanism to the wheels.
- 🛡️ Anthers — rubber corrugations that prevent abrasives from entering the mechanism.
Particular attention should be paid to manufacturing materials. Gears and racks often undergo special heat treatment to increase surface hardness. This is necessary to withstand constant shock loads from road unevenness. Plain or antifriction bearings provide smooth operation and minimize friction between moving parts.
⚠️ Attention: Damage to the protective anthers (corrugations) leads to rapid leaching of the lubricant and sand getting into the mechanism. This is the most common reason for the failure of an expensive unit.
Comparative table of mechanism characteristics
To clearly understand the differences between the main types of force transmission devices, let’s consider their technical parameters. These characteristics will help determine which type is (more suitable) for various operating conditions and vehicle requirements.
| Parameter | Rack and pinion mechanism | Worm mechanism | Screw mechanism |
|---|---|---|---|
| Control precision | High | Average | High |
| Compactness | High | Low | Average |
| Maintenance cost | Low | High | Average |
| Application | Passenger cars | Trucks, SUVs | Special equipment, old cars |
As can be seen from the table, rack and pinion mechanisms win in most parameters for passenger vehicles. They provide the very “sharpness” of steering that drivers of sports and city cars appreciate. Worm-worm systems remain relevant where maximum reliability and the ability to withstand extreme loads are required, albeit at the expense of accuracy.
Screw mechanisms, although less common, have the unique property of self-braking. This means that the wheels will not spontaneously return to their original position under the influence of inertia or road gradient without driver intervention. This property is valuable for heavy equipment operating in difficult conditions.
Typical faults and diagnostic methods
Even the most reliable device wears out over time. The most common problem is the appearance of backlash. This is the gap between the teeth of the gear and rack, which occurs as a result of natural wear and tear on metal surfaces. The driver feels this as a "blind spot" in the center of the steering wheel, when turning does not cause immediate reaction from the wheels.
Another common problem is leakage of working fluid in systems with power steering. Over time, oil seals and gaskets become tanned and lose their elasticity, beginning to leak oil. This not only creates stains on the asphalt, but also leads to air in the system, the appearance of pump whine and loss of amplification efficiency. In such cases, replacement of the repair kit or the entire assembly is required.
☑️ Steering wheel diagnostics
A knocking sound when driving over uneven surfaces is a sure sign of wear on the steering rod joints or internal rack bushings. If you ignore this sound, the play will increase, which will lead to uneven tire wear ("eating" the rubber) and deterioration in directional stability. Diagnostics should be carried out regularly, especially after the winter season, when the roads are covered with reagents.
Electric amplifiers have their own problems, often related to electronics. Torque sensors can become dirty or damaged, causing the steering to jerk or the power to shut off completely. In such cases, a corresponding error lights up on the dashboard, requiring computer diagnostics.
Adjustment and Maintenance
Many drivers wonder whether it is possible to adjust the mechanism themselves. Some models have an adjusting nut with a locknut to reduce the clearance between the worm and the sector or the gear and the rack. However, this procedure requires precision and special tools. Excessive tightening will lead to the steering wheel biting and spontaneously returning to the center, which is dangerous.
Basic maintenance consists of timely replacement of lubricant and checking the integrity of protective elements. For rack and pinion mechanisms, it is important to use a lubricant with suitable characteristics that will not lose its properties at low temperatures. Frozen lubricant can cause damage to the teeth the first time you turn the steering wheel sharply in winter.
The secret to long service life of the steering rack
Many people do not know that turning the steering wheel all the way and holding it in this position for more than 5 seconds creates critical pressure in the power steering system. This can lead to squeezing out the seals and causing pump failure. Try not to hold the steering wheel in extreme positions for long.
It is also necessary to monitor the condition of the steering tips. They have a hinged joint that is protected by a boot. If the boot is torn, the ball pin quickly wears out, knocking and play appear. Replacing the tips is a relatively simple procedure, but after it a wheel alignment adjustment is required.
⚠️ Attention: After (any) work related to disassembling the steering mechanism or replacing rods, adjusting the wheel alignment angles (alignment) is a mandatory procedure.
Questions and answers (FAQ)
How often should the condition of the steering gear be checked?
It is recommended to carry out a visual inspection and check for play at each scheduled maintenance, that is, every 10-15 thousand kilometers. Diagnostics are also required after falling into deep holes or strong impacts on the curb.
Is it possible to drive if you hear a knock in the steering rack?
A short trip to the service is possible, but operating a car with faulty steering is prohibited by traffic regulations. A knocking noise indicates the presence of play, which can lead to loss of control in an emergency.
Which is better: hydraulic power steering or electric power steering?
The electric power steering (EP) is more economical, easier to maintain and does not require fluid replacement. The hydraulic booster (power steering) provides a more natural feeling of the road and better absorbs shock from the wheels, but is more complex in design and requires regular oil changes.
Why is the power steering pump humming?
The humming noise is most often caused by low fluid levels, air getting into the system, or wear and tear on the pump itself. The cause may also be a clogged filter mesh in the tank or the use of low-quality fluid that does not meet the specifications.
Does wheel size affect the performance of the steering mechanism?
Yes, installing larger diameter or wider wheels increases the contact patch and turning resistance. This places increased stress on the steering gear and power steering, which can lead to accelerated wear or overheating.