Your vehicle consists of different parts. “Turning” is a fundamental function of a vehicle that is produced by a power steering system that changes the vehicle’s direction by turning the steering wheel which further turns the tires. This article mainly explains the power steering system working, types, function, parts, and applications.
What is a Power Steering System?
A power steering system is a mechanical device that helps the driver to turn the vehicle by increasing the steering force required to turn the wheels, which makes it easier to steer or move the vehicle.
The steering system contains a power steering pump. This pump compresses the hydraulic fluid and ensures the entry of the hydraulic fluid into the steering system, which supports the driver to steer the vehicle’s steering wheels.
An electric or hydraulic actuator provides controlled power to the steering device so that the driver can put less energy to steer the steering wheel when driving at normal speeds or when the vehicle is stationary.
The power steering is designed in such a way that it provides feedback to the vehicle computer (usually PCM) about the forces acting on the wheels. This system contains a slotted rotor that turns to allow power steering fluid to enter the pump.
A vehicle’s power steering is an essential component of vehicle dynamics, which combines several mechanical parts at specific wrench angles to steer the vehicle’s front wheels in response to passenger inputs through the steering wheels.
Nowadays, 80% of all vehicles on the road have power steering systems that have become an essential requirement of every vehicle.
How does Power Steering Work?
A power steering system transforms the rotary motion of the steering wheel into a swiveling motion of the road wheel so that the rims of the steering wheel can steer a long distance to move the road wheel a short distance.
The power steering system works differently depending on the force multiplier used. Therefore, to understand how power steering works, you need to understand the following methods individually.
1) Hydraulic Steering System
The hydraulic power steering (HPS) system uses a hydraulic system to increase the steering input force and smoothly steer the front wheels. This force produces through a chain of different parts such as highly compressed hydraulic oil, hydraulic lines, hydraulic rotor pump, hydraulic cylinder, and a linking mechanism that connects the hydraulic system to the steering system.
The hydraulic steering system works in the following way:
- As the driver sends input by turning the steering wheel, the engine-driven hydraulic pump initiates pumping the highly pressurized hydraulic oil through the line.
- The hydraulic force produced by the pump enters the cylinder, which smears this pressure to the hydraulic cylinder piston.
- The high-pressure piston starts running from one end to the other, pushing more fluid through the line. As the piston moves, the driver’s input force multiplies numerous times.
- Next, the high-pressure fluid delivered by the cylinder employs pressure to the pinions connected with the clutch device, thereby applying a large force to the rack gear to steer the front wheels.
2) Electric Power Steering System (EPS)
Electric power steering is one of the latest types of power steering systems. In this system, an electric motor is utilized to multiply the steering input force instead of the hydraulic fluid. An electric power steering system works in the following way:
- As the driver sends input via the steering wheel, an electronic sensor mounted on the steering column detects the inputs and sends them to the PCM (powertrain control module).
- The PCM analyzes the steering wheel input and delivers a voltage signal to the electric motor at the end of the steering column. The gears of the electric motor always mesh with the pinion gears.
- The electrical control unit sends the voltage signal so that the electric motor powered by the automobile’s battery can start and can deliver a specific torque based on the received voltage signal’s value.
- As soon as the motor starts, the gears which maintain constant mesh with the pinion gears begin to transmit the multiplied torque to the pinion, which transfers this torque to the fixed rack.
- When this pinion exerts a torque on the rack, the rack moves to steer the front wheels as needed (via linked tie rods).
Types of Power Steering Systems
The power steering system has the following three types:
- Hydraulic steering system
- Electric steering system
- Linkage power steering
- Electro-hydraulic steering system
- Integral power steering
1) Hydraulic Steering System
A hydraulic power steering (HPS) system utilizes a hydraulic system to multiply a force to the steering wheel inputs into the steering of the vehicle roadwheel (usually the front wheels). The hydraulic force is generally generated by a pump. An engine is used to drive the pump.
A double-acting hydraulic cylinder forces the steering gears to turn the road wheel. These steering wheels contain a valve to control the flow of the cylinder.
When you apply more torque to the steering column and steering wheel, the valve increases the fluid flow rate from the cylinder. In this way, a greater force will be exerted to turn the wheels. When the piston of the hydraulic cylinder touches the end of its stroke, the pressure valve stops the risky accumulation of pressure.
Since the hydraulic power steering pump is a positive displacement pump, the flow provided by this pump is proportional to the engine speed. It means that the steering moves naturally faster at high engine speeds than at low engine speeds.
Advantages of Hydraulic Steering System
- The hydraulic steering system has no advantages in cars.
- It’s all components are serviceable.
- In the case of a truck, it is less expensive than EPS
Disadvantages of Hydraulic Steering System
- It has high weight than EPS
- It has high price than EPS (for cars)
- More response lag compared to EPS (due to backlash in construction)
- It needs high maintenance
- The system turns heavier than manual steering when the power assistance fails.
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2) Electric Power Steering System
Motor-driven power steering (MDPS) or electric power steering system (EPS) uses an electric motor instead of a hydraulic system to turn the wheels of the vehicle.
Electric power steering systems are most commonly used in modern cars because they are more responsive and efficient than traditional hydraulic power steering systems.
This steering system contains an electric motor. This motor is installed on the rack and pinion assembly or the steering column. The engine control unit (ECM) of the vehicle takes information from the power steering sensors and utilizes this information to control the electric motor.
The steering wheel sensors detect the steering angle and the speed of your car. Based on this input, the ECU regulates the amount of electrical assistance delivered by the motor. The motor puts torque on the rack and pinion assembly or steering column to assist the driver in turning the wheels.
One of the major benefits of EPS is that it is more energy-efficient compared to conventional hydraulic power steering systems. This system only consumes power when the driver is turning the wheel. It also provides more consistent and predictable steering feel than hydraulic power steering systems.
A mechanical linkage between the steering gear and the steering wheel is always maintained in the electric power steering systems. The mechanical linkage can be used as a backup device in case of any power or part failure that cannot deliver assistance.
Advantages of Electric Steering System
- It has less price than HPS (for cars)
- Its assembly is simple
- It has light weight
- It requires less maintenance than a hydraulic system
Disadvantages of Electric Steering System
- It has maximum non-serviceable components.
- The power assistance unit locates on the steering column, so a heavyweight column.
3) Electro-hydraulic Power Steering
Electro-hydraulic power steering system (EHPS) is an improved version of the hydraulic system in which a hydraulic steering pump is installed which is driven by an electric motor instead of an engine. It utilizes both electrical power and hydraulic pressure to deliver steering assistance to the driver
This steering system is usually used in vehicles with heavier loads or larger engines, including SUVs and trucks.
The major advantage of the EHPS is that it gives more efficient and precise steering compared to conventional hydraulic power steering systems.
4) Integral Power Steering
The Integral power steering combines the hydraulic power steering system with other systems of your car including the suspension system and the rake system. This system has a special integral power-assist gearbox, hydraulic lines, and a power steering pump. It has a hydraulic piston that is installed in the gearbox of the steering.
The gearbox has a control valve, a hydraulic piston, a sector gear arrangement, and a conventional worm. According to the integral power steering design, the control valve may have different designs, such as a rotary valve or spool valve.
In an integral power steering system, a hydraulic pump is used to generate the hydraulic pressure. An engine is used to drive this pump. The output hydraulic pressure is utilized to help the vehicle driver to steer the wheels.
5) Linkage Power Steering
In this system, the power cylinder is attached to the steering linkage. The linkage power steering has a hydraulic control valve. One side of this valve is attached to the center link or drag link.
The steering gear and steering wheel send input signals to the control valve.
The control valve reacts, opens the connection, and directs the hydraulic fluid to the hydraulic ram by turning to the right or left. This ram is linked to the steering linkage. The flow of liquid on one side of the ram’s piston is used to regulate the power direction. A major disadvantage of this steering system is that it can be easily damaged.
Components of the Power Steering System
The power steering system has the following major components:
- Power steering pump
- Pressure tube
- Control valve
- Steering wheel
- Shaft
- Steering gear
- Pitman arm
- Ball joints
- Steering arm
- Stub box
- Steering knuckle
1) Steering Wheel
The steering wheel is also known as a control wheel. This part of the power steering is used to turn the car. It has a windshield wiper switch, light switch, traffic indicator switch, and more. This wheel is also known as a driving wheel. The handwheel is also a type of steering control for the vehicle.
Steering wheels are most commonly used in the latest vehicles such as tractors, heavy and light trucks, buses, cars, etc.
2) Shaft or Steering Column
The shaft also called a steering column that is mounted in a hollow steering column. As the driver steers the wheel, the steering column also rotates. In this way, the movement of the steering wheel is transferred to the steering gears.
3) Steering Gear
The steering gear is one of the most important parts of the power steering system. One end of the pitman’s arm is splined to the rocker arm of the steering gear, and the other end is linked with the drag chain via a ball joint.
The steering gear transmits the input signal of the driver’s steering to the steering linkage mechanism to turn the vehicle wheel. It also multiplies the driver’s change of direction so that the front wheels can turn higher than the steering wheel.
4) Pitman Arm
The main function of the Pitman arm is to translate angular or rotary motion into linear motion, or vice versa. When you turn the steering wheel to the left or right, the Pitman arm transfers the movement to the tie rod that it gets by the steering gear. If the automobile has a suspension lift, then a “drop pitman arm” uses to adjust the steering.
5) Ball Joints
A ball joint is a ball bearing that connects the steering knuckle with the control arm. The bearing bolts are tapered and threaded and mounted in the tapered holes in the steering knuckles. The protective casing keeps dust away from the joint assembly.
6) Drag Link
This steering system component transforms the steering arm’s bending arc into a linear movement in the plane of the other steering links. The drag links connect the steering arm with the drop arm. In some cases, it is linked with the assembly of the tie rod.
7) Steering Arm
The steering arm is the arm with which the steering force transfers from the steering gears to the drag link.
The major objective of the steering arm is to enable the driver to turn the car correctly and safely.
8) Stub Axle
The movement of the steering wheel is transferred through the steering gear to the pitman’s arm. After this, this movement is transferred to the drag link. The drag link further transmits this motion to the stub axle, which spins around the kingpin. The stub axle is used to steer the right wheel of the vehicle.
9) Steering Knuckle
In the suspension of a vehicle, a steering knuckle is a component that has the spindle or wheel hub and connects with the steering and suspension parts. It is also known as the hub, upright, spindle, and steering knuckle.
10) Power Steering Pump
The power steering pump compresses the hydraulic fluid and increases the pressure of the fluid. After this, the steering pump pumps the pressurized into the cylinder of the steering system.
Read More: How to Change Power Steering Fluid?
Power Steering Pump Replacement Cost
If the power steering pump of your vehicle has been damaged and cannot be repaired, it must be replaced. Several factors affect the cost of replacing a power steering pump. Some of these factors are given below:
- Vehicle model: The first and most important factor that affects the steering pump replacement cost is the type of vehicle you drive. The model and make of your vehicle have a significant impact on the cost of replacing a power steering pump.
- Your living area: Another factor that affects the cost of replacing a steering pump is the location or area where you live. Because the cost of everything varies according to different areas.
- Type of Brand: The power steering systems of different brands have different costs. Some brands have very high costs while some have low costs.
- Labor cost: If you are replacing the steering system yourself, then labor cost won’t affects you.
The average replacement of the power steering pump is typically between $200 and $350. This price includes the cost of parts and labor. As we discussed before that according to the model of your vehicle and the area where you live, this cost may be increased.
Advantages and disadvantages of Power Steering System
The steering system has the following major advantages and disadvantages:
Advantages of Power Steering System
- The steering system provides a controlled and accurate turning on the road.
- It provides steering wheels stability and control to the driver which is very helpful in wet road conditions.
- The power steering permits the driver to make a smaller circular steer at a lower speed.
- It is very handy on tougher roads or grounds.
- It provides great straight-line stability.
- The steering system has the capability to deliver high force.
- This system provides an easy changing lane because if the driver is driving the vehicle at high speed and he wants a quick lane change, then in that condition, the steering system provides help for a quick lane change.
Disadvantages of Power Steering System
- The power steering system has a high cost because it consists of various components such as a steering pump, shaft, steering wheel, pitman’s arm, and steering column, etc., due to that, its cost increases.
- It has a complex design.
- The maintenance of the power steering system is very complicated.
Power Steering Vs Manual Steering
The main difference between the power steering system and the manual steering system is given below:
| Power Steering | Manual Steering |
|---|---|
| A steering system that uses some source of power to steer the vehicle wheels is known as power steering. | A steering system in which manual power is utilized to turn the wheels is called a manual steering system. |
| Car steering is an example of power steering. | Bicycle steering is an example of manual steering. |
| It responds very quickly. | It has a slow response. |
| It turns the vehicle wheels very quickly. | This system turns the wheel slowly. |
| Power steering has a very high cost. | The manual steering has a low cost. |
| It has a high weight. | It has light weight. |
| It has a complex design. | It has a simple and reliable design. |
| This system has a power steering gear assembly, lines, hoses, a fluid reservoir, and a hydraulic pump. | This system has linkages, a manual gearbox, a column and steering wheel, a pitman arm, and pinion and rack assembly. |
FAQ Section
What is a steering system?
The steering system of a car is the set of various parts that permit the driver to adjust the direction of the car’s movement. The steering system contains several components such as the tie rods, steering gear, steering column, and steering wheel.
What are the types of Power Steering Systems?
There are major three types of steering systems that are given below:
- Hydraulic Power Steering System
- Electronic/Electric Power Steering System
- Electro-hydraulic system
- Integral Power Steering
- Linkage Power Steering
What is the function of a Power Steering?
The main function of a power steering system is to help the driver to turn the vehicle by increasing the steering force required to turn the wheels, which makes it easier to steer or move the vehicle.
What are the components of steering system?
- Steering wheel
- Steering shaft
- Steering column
- Tie rods
- Rack
- Idler arms
- Pitman arm
- Drag or center link
What happens when a pitman arm fails?
When your car’s pitman arm or idler arm goes bad, it may lead the car not to respond properly when you steer the steering wheel. As a result, the car may pull to one side of the road, or the steering feels hard to control.
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