Power Steering Decoded: Understanding Types, Failures, and Maintenance for Smooth Steering

How Does A Power Steering work?

Power steering is a system in vehicles that assists the driver in steering by reducing the effort required to turn the steering wheel. The basic operation of power steering involves the following components:

Steering Wheel: The driver controls the direction of the vehicle by turning the steering wheel.

Power Steering Pump: The power steering pump is typically driven by the vehicle's engine. It creates hydraulic pressure that powers the steering system.

Hydraulic Fluid: Power steering systems use hydraulic fluid, often referred to as power steering fluid, to transmit and amplify the force applied by the driver to the steering wheel.

Power Steering Gear or Rack: The hydraulic pressure generated by the power steering pump is directed to a power steering gear or rack, depending on the type of steering system.

Power Assist Mechanism: Within the power steering gear or rack, there is a power assist mechanism that multiplies the force applied by the driver to make steering easier.

Control Valve: The control valve in the power steering system regulates the flow of hydraulic fluid, determining the level of power assistance based on the driver's steering input.

When the driver turns the steering wheel, it sends a signal to the power steering pump to start generating hydraulic pressure. The hydraulic fluid is then pressurized and directed to the power assist mechanism in the steering gear or rack. The power assist mechanism multiplies the force applied by the driver, making it easier to turn the wheels.

In traditional hydraulic power steering systems, the level of power assistance remains constant. However, in modern electric power steering systems, sensors and control modules detect the driver's steering input, vehicle speed, and other factors to provide variable assistance, adjusting the level of power assistance based on driving conditions.

Figure 1: Picture courtesy of  https://mechasource.blogspot.com/2019/04/an-introduction-to-power-steering-pump.html

The Three Types Of Power Steering Pumps

There are primarily three types of power steering pumps commonly used in modern vehicles: hydraulic power steering pumps, electric power steering pumps, and electro-hydraulic power steering pumps. Let's briefly explain each type and discuss their pros and cons:

Hydraulic Power Steering Pump:

This type of pump is driven by the vehicle's engine through a belt and pulley system.

It uses hydraulic pressure generated by a rotary vane or gear mechanism to assist in steering.

Pros:

• Provides strong and consistent power assist, especially at low speeds.
• Relatively simple and robust design.
• Suitable for larger vehicles and heavy-duty applications.

Cons:

• The pump continuously draws power from the engine, which can reduce overall fuel efficiency.
• Requires regular maintenance, such as fluid checks and belt replacements.
• Can be prone to leaks and noise issues over time.

Electric Power Steering Pump:

Instead of being driven by the engine, this type of pump is powered by an electric motor.

It uses sensors and a control module to determine the amount of power assistance required.

Pros:

• Offers better fuel efficiency since it only operates when assistance is needed.
• Provides more precise and adaptable power assistance.
• Generally lighter and more compact, allowing for easier installation in vehicles.

Cons:

• Relies on electrical power, so a failure in the electrical system can result in a loss of power steering.
• In rare cases, an electric power steering pump failure can lead to a sudden loss of steering assist.
• May not provide the same level of steering feel as hydraulic systems, which some drivers prefer.

Electro-Hydraulic Power Steering Pump:

This type combines the characteristics of both hydraulic and electric power steering systems.

It utilizes an electric motor to drive a hydraulic pump, which then generates the necessary hydraulic pressure.

Pros:

• Offers a balance between the strong power assist of hydraulic systems