The mechanical challenges of early steering
In the early days of automobiles, steering was entirely mechanical. This meant that turning the steering wheel required a significant amount of physical effort to move the car’s wheels. Consequently, larger cars and family vehicles often had oversized steering wheels, making driving akin to handling a sailboat.
Power steering to the rescue
Power steering addressed this challenge by introducing hydraulic assistance, and later, electric assistance. Although the concept of power steering has been around for nearly a century, it has evolved significantly over time, culminating in its present form as Electric Power Steering (EPS) in the early 2000s.
Understanding mechanical steering
Mechanical steering systems typically employ the Rack & Pinion method. This mechanism consists of the “rack,” a horizontal bar connecting the two front wheels, and the “pinion,” a rotational device that responds to steering wheel movement. When you turn the steering wheel, the rack moves, causing both wheels to turn at the same angle.
The primary objective is to convert the rotary motion of the steering wheel into the lateral motion necessary for the wheels to turn left or right. Although early steering mechanisms, such as those found on horse-drawn carts, relied on boat rudder-like designs, they lacked the ability to self-center, making it challenging to maintain a straight path.
The rack and pinion system essentially functions as gears: when you rotate the steering wheel, a toothed gear moves the pinion and, consequently, the wheels at a corresponding rate.
The game-changing role of electric power steering (EPS)
Electric power steering streamlines the process by incorporating an electric motor between the steering wheel and the pinion. Importantly, this design does not entirely decouple the movement of the steering wheel from the wheels’ motion. Instead, the electric motor enhances the steering wheel’s movement through a system of planetary gears.
The electric motor relies on sensors to detect the driver’s steering wheel movements and transmits this data to a control unit. This control unit can then adjust the level of amplification applied by the motor. The amount of amplification varies based on factors like the car’s speed, ensuring that abrupt or jerky movements are reduced at higher speeds.
If you’ve ever attempted to turn the steering wheel when the car is turned off, you’ll understand the significant difference. It’s a challenging task. The planetary gears in electric power steering systems enable you to turn the steering wheel with the typical effort while allowing the electric motor to substantially strengthen the rotation of the pinion. As a result, you can steer the car with significantly less effort than would otherwise be required.