The heart of an automobile is the engine, but what’s the use, if you can’t steer in the right direction. The steering wheel is as important as any other component of a vehicle, and it has existed since the inception of cars. The steering wheel has evolved, from a single handle from the uni-wheel in the front, as in the first automobiles, to a full-fledged wheel, we are familiar with. But that’s not it, even the steering wheel that is used in cars today can be categorized into various types.
Over more than a century into existence, there have been two perfect steering designs, that have been fitted and worked in over millions of vehicles; the most commonly used rack and pinion system and the conventional system know as the Recirculating Ball Steering system.
The rack and pinion is the most simplistic and impactful steering wheel system that ever existed. As the name suggests, the two important components of the car steering are two gears; rack( the linear gear) and the pinion( the circular gear). This system, because of its simplicity and light weight, is employed in most of the cars, except the heavy-duty vehicles.
The car steering system has a long shaft, and connceted to the other end, is the pinion. The pinion gear is positioned on the top of the rack. It rack moves as the pinion gear rotates. On the end of the rack are the tie rods, these are what that connects the rack to the steering arms, which are further connected to the wheel hub.
As the steering wheel of car steering wheel is rotated, the shaft rotates. This, in turn rotates the pinion gear, which is on top of the rack. The rotation of the pinion, makes the rack move linearly, moving the tie rods. The tie rods, which are connected to the steering arm, which are then connected to the wheel hub move with the linear movement. The size of the pinion decides the effort needed for a 360-degree turn. The larger the pinion gear, more responsive the car steering is, but it makes harder to control the vehicles.
While the rack and pinion car steering system has been equipped in various daily-commute cars. But when it comes to heavy-duty and commercial vehicles, the recirculating ball type car steering system rules out rack and pinion.
The recirculating ball type car system consists of a worm gear and a sector gear. The steering wheel is connected to a threaded shaft which is connected to a block. The worm gear is quite big and goes through the block which is threaded in such a way it allows the worm gear inside. This block has gear teeth outside of it to which the sector gear is connected. This sector gear is then connected to the pitman arm while the pitman arm is attached to the tie rod. There are ball bearings inside the block that fill the thread of the worm gear. The working is simple just like rack and pinion.
The car steering wheel rotates the shaft connected to it, and with it the worm gear rotates. The gear is bolted on to prevent its up and down movement. As the worm gear rotates, the makes the block move. The moving block makes the sector move, which in turn moves the pitman arm. The thread of the worm gear, inside the block, is filled with ball-bearings, to reduce friction and avoid slippage.
With both rack and pinion and recirculating ball type car steering, the manual steering are covered with. But there are two more types of secondary car steering systems; power steering and hydraulic car steering systems. These are hastily replacing the old, manual car steering systems, for their efficiency and ease of use. So let’s learn about them too.
While both rack and pinion and recirculating car steering systems are efficient, they require a lot of hard work. This is where hydraulic car steering system, saves from musculing up the arms. The only difference between manual and hydraulic car steering system is that it reduces the efforts, using some science. The steering gear’s internal cavity is divided in two chambers, each houses a sealed piston attached to the rack. Applying force to one side of the piston forces the fluid on the other side to a return to a reservoir, hence providing a steering assistance. This reduces the force needed to move the steering, despite the hefty curb weight of the vehicle.
Alike the hydraulic car steering system, the power steering assists the driver to make minimal efforts to turn the wheels. In here, an electric motor is mounted to the side of a rack housing, which drives a ball-screw mechanism via a toothed rubber belt. This screw engages a spiral cut gear in the outside of the steering rack, which in turn moves the steering arm accordingly. The power steering fits a torque sensor, which reads the steering wheels and the rotations, and directs the control computer to assist.
With the manual and power/hydraulic assisted car steering covered, let’s jump into some innovative technology that have made the steering wheels more effective and effortless.
Nissan was the first OEM to reveal a steer-by-wire system. The system reads the driver’s intention by torque applied and the degree of turning. The computers reads the inputs from the steering wheel. Each wheel is controlled independently so the system is able to improve stability and maneuverability.
Besides this, four-wheel steering has been into existence for a long while luxury sedans like Mercedes Benz S-Class, Rolls Royce Ghost, even supercars like Lamborghini Aventador equip this technology. In this car steering system, the rear wheels can also turn up to certain angles. At lower speeds, the rear wheels turn in opposite direction, this reduces the turning radius of the vehicles. While at higher speeds, the rear wheels turn in same direction, to increase the agility and stability at the same instance.
The car steering system has also been added with lane-keep assist and adaptive cruise control, these system make minor changes by steering the vehicle, to keep it inside the lane. These driver assistance aids reduce the fatigue of the driver for longer routes and make the driving effortless.
The car steering system has evolved over the centuries. The manual steering systems have been replaced by power assisted ones, and the innovative technology has made the vehicles more agile and maneuverable. But with this pace and the increase in popularity of autonomous vehicles, it won’t be long that steering wheels will be completely vanished and taken over the artificial intelligence.