8 Types of Steering Gearboxes and Their Functions.

A steering system in a vehicle is important to give the direction to the vehicle according to the driver. The steering gearbox in the steering system is important as it multiplies the turning effort applied to the steering wheel by the driver. The steering gearbox is also responsible for the wear and tear of the tires.

In this article, I will discuss the 8 different types of steering gearboxes and the functions of these gearboxes. So, dip your nose and read the article.

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Types of Steering Gearboxes

If the steering wheel is connected directly to the steering linkage, it would require a great effort to move the front wheels. Therefore, to assist the driver, a reduction system is used having a movement ratio between 10:1 to 22:1, the actual value depending upon the type and weight of the vehicle. The steering gear is a device for converting the rotary motion of the steering wheel into straight line motion of the linkage with a mechanical advantage.

The steering gear linkage into a box called the steering gearbox. There are many different designs of steering gearboxes in automotive cars. So the types of steering gearboxes are-

1. Worm and sector steering gearbox.
2. Worm and roller steering gearbox.
3. Cam and double lever steering gearbox.
4. Worm and ball bearing nut steering gearbox.
5. Cam and roller steering gearbox.
6. Cam and peg steering gearbox.
7. Recirculating ball steering gearbox.
8. Rack and pinion steering gearbox.

Each of these types of steering gearboxes is discussed below with their functions.

#1. Worm and Sector Steering Gearbox

Essentially the steering gearbox makes the connection between the steering shaft and the steering linkage. In the worm and sector steering gear, the worm on the end of the steering shaft meshes with a sector mounted on a sector shaft.

When the worm is rotated by rotation of the steering wheel, the sector also turns rotating the section shaft. Its motion is transmitted to the wheel through the linkage. Note that the sector shaft is also known as pitman arm shaft, pitman shaft, roller shaft, steering arm shaft, or cross shaft.

Function

Here are some functions and features of a worm and sector steering gearbox:

1. Worm and sector steering gearboxes can be adapted for use in various types of vehicles, including cars, trucks, and industrial machinery, making them versatile in different automotive and industrial applications.
2. The worm gear in the gearbox provides a high degree of gear reduction. This reduction helps in translating the relatively fast and low-torque input from the steering wheel into the slower, high-torque motion required to turn the vehicle’s wheels.
3. Worm gears inherently have a self-locking property. This means that when the steering wheel is not being actively turned, the worm gear prevents the wheels from moving on their own due to external forces, providing stability to the vehicle.
4. Worm and sector steering gearboxes are known for their durability and reliability. The simple design and fewer moving parts contribute to their robustness, making them suitable for various vehicle applications.
5. In some applications, the worm and sector steering gearbox are used in manual steering systems. The mechanical advantage provided by the gearbox assists the driver in turning the wheels with less effort.

#2. Worm and Roller Steering Gearbox

In the worm and roller steering gearbox, a two-toothed roller is fastened to the sector or roller shaft so that it meshes with the threads of the worm gear or shaft at the end of the steering shaft or tube. When the worm shaft is turned, it causes the roller to move in an arc to rotate the roller shaft; and at the same time turns on the pin connecting it to the shaft.

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The roller is mounted on ball bearings. The worm shaft is mounted on bearings designed to resist both radial and end thrust. This type of steering gear is widely used in American passenger cars.

Function

The functions of worm and roller types of steering gearboxes are –

1. The rolling contact between the worm and roller contributes to a smoother steering operation, enhancing the overall driving experience for the vehicle’s occupants.
2. The gearbox uses a rolling contact mechanism between the worm and roller gear. This design reduces friction compared to sliding contact in traditional worm and sector gearboxes, leading to smoother operation and less wear over time.
3. The gearbox design provides a mechanical advantage, assisting the driver in overcoming resistance in the vehicle’s front-end components, resulting in a more responsive steering experience.
4. Like the worm and sector gearbox, the worm and roller gearbox is often designed to be compact, fitting into the limited space available in the vehicle’s engine compartment.
5. The design of the worm and roller steering gearbox allows for adaptation to different types of vehicles, making it versatile for use in cars, trucks, and various industrial applications.

#3. Cam and Double Lever Steering Gearbox

In the cam and double lever steering gearbox, a special worm, called a cam, replaces the worm used in the two types just described above.  The cam is cylindrical, its actuating part being a groove of the variable pitch made narrower at the center than at the end. This provides non-reversibility in the centre part of the cam where most of the car steering takes place.

The twin levers are mounted on the cross shaft and are located so that the studs engage the cam from the side. When the cam is turned, the studs move along the cam groove to cause the lever to swing through an arc, thus turning the cross shaft.

Function

The function of cam and double lever types of steering gearboxes are –

1. The primary function of the Cam and Double Lever Steering Gearbox is to convert the rotary motion of the steering wheel into lateral motion, allowing for the controlled turning of the vehicle’s wheels.
2. It employs a cam and double lever mechanism, where the cam converts the rotary motion of the steering shaft into an up-and-down motion, and the double lever translates this motion to move the tie rods, steering the wheels.
3. It enhances the driving experience for the vehicle’s occupants.
4. Depending on the specific design and construction, Cam and Double Lever Steering Gearboxes can be durable, with fewer components subject to wear and tear.
5. The design of the Cam and Double Lever Steering Gearbox allows for adaptation to different types of vehicles, making it suitable for use in various automotive and industrial applications.

#4. Worm and Ball Bearing Nut Steering Gear

In the worm and ball bearing nut steering gearbox, a ball nut is mounted on the worm of the steering shaft. The worm and the nut have mating spiral grooves in which steel balls circulate to provide a frictionless drive between the worm and the nut. Two sets of balls are used, with each set operating independently of the other.

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A ball return guide is attached 10 the outer surface of the nut. When the steering shaft is turned to the left or right, the ball nut is moved up and down by the balls that roll between the worm and nut. A sector gear mounted on the sector shaft meshes with the ball nut so that it gets motion by the ball nut.

Function

Here are some functions of worm and ball bearing nut types of steering gearboxes –

1. It incorporates a worm gear, which is a threaded shaft, to engage with the ball-bearing nut. This threaded interaction converts the rotary input into linear motion.
2. The use of a ball-bearing nut in the steering gear reduces friction, providing smoother operation and improving the efficiency of the steering mechanism.
3. The combination of the worm gear and ball-bearing nut can result in low backlash, providing a more precise and responsive steering feel.
4. The use of ball bearings in the steering gear enhances durability by reducing friction and wear on the components, contributing to a longer lifespan of the steering system.
5. In some applications, this type of steering gearbox may be used in manual steering systems, assisting the driver in turning the wheels with relative ease.

#5. Cam and Roller Steering Gearbox

In the cam and roller steering gearbox, a cam meshes with the roller. As the cam rotates, the roller is compelled to follow the cam and in doing so causes the rocker shaft to rotate, thus moving the drop am1. The contour of the cam is designed to mesh with the arc made by the roller maintaining a constant depth of mesh and evenly distributing the load and wear on the mating parts.

Function

Here are some functions of the cam and roller types of steering gearboxes –

1. The use of roller elements in the gearbox reduces friction compared to sliding mechanisms, leading to smoother operation and potentially extending the lifespan of the steering components.
2. The cam and roller arrangement contributes to a smooth steering operation, providing a more comfortable driving experience for the vehicle’s occupants.
3. Depending on the specific design and construction, Cam and Roller Steering Gearboxes can be durable, with reduced wear on the components due to the low-friction roller mechanism.
4. The design of the Cam and Roller Steering Gearbox allows for adaptation to different types of vehicles, making it suitable for use in various automotive and industrial applications.

#6. Cam and Peg Steering Gearbox

In the cam and peg steering gear attached to the rocker’s arm is a tapered peg that engages in the cam. When the cam rotates, the peg moves along the groove causing the rocker shaft to rotate.

Function

The functions of cam and peg steering gearboxes are –

1. The cam and peg mechanism might be designed to provide smooth steering operation, contributing to a comfortable driving experience.
2. Like other steering gear systems, a Cam and Peg Steering Gearbox would likely aim to provide a mechanical advantage, allowing the driver to turn the steering wheel with less effort while still exerting sufficient force to control the vehicle.

#7. Recirculating Ball Steering Gearbox

The recirculating ball steering gear is similar to the worm and ball-bearing nut steering gear. The balls are contained in a half nut and transfer tube. As the cam or worm rotates, the balls pass from one side of the nut through the transfer tube to the opposite side. As the nut cannot turn, the movement of the balls along the track of the cam carries the nut along with it and rotates to the rocker shaft.

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Function

The functions of recirculating ball steering gearboxes are –

1. The use of ball bearings in the recirculating ball nut reduces friction compared to sliding mechanisms, resulting in smoother steering operation.
2. The design often provides a mechanical advantage, allowing the driver to turn the steering wheel with less effort while still achieving the necessary force to control the vehicle.
3. The use of ball bearings contributes to the durability of the system by reducing wear on the components, potentially leading to a longer lifespan of the steering gearbox.
4. In some applications, this type of steering gearbox may be used in manual steering systems, assisting the driver in turning the wheels with relative ease.
5. The recirculating ball design may provide a self-aligning torque, helping the steering system return to its straight position after a turn and contributing to the vehicle’s stability.

#8. Rack and Pinion Type Steering Gearbox

In the rack and pinion steering gearbox, a pinion is mounted on the end of the steering shaft. It engages with a rack that has ball joints at each end to allow for the rise and fall of the wheels. The rods connect the ball joints to the stub-axles. The rotary movement of the steering wheel turns the pinion which moves the rack sideways. This movement of the rack is converted to the wheels.

Diagnosing Problems with Rack and Pinion Steering

Factors other than the steering system itself can give a “wandering” feeling in the rack and pinion steering, like loose worn wheel bearings or suspension ball joints. In this way, rack and pinion steering is just like any other type. Suspension joints and wheel bearings need to be snug before finding anything about what is happening in the steering system.

Sometimes this inner joint wear is bad enough and can feel it by pulling up and down on the inner end of the tie rod. There may even be a clunking sound though this is rare. But if there is even 1 or 2 mm of play in this ball joint, the steering will not be right.

Sometimes major wear will be on the outer tie rod ends. Here also, check by pulling up and down and sideways on the joint. Allowable play here is not over 1 mm.

Strangely enough, it is rare that gear teeth on the rack or on the pinion gear get excessive wear. These surfaces are very lightly loaded, rubbing speeds are low and lubrication is good. These parts rarely need to be replaced in the life of the car. It is still the ball joints that are the most critical wear areas.

Usually the ball joints socket assembly screws on the end of the rack, with some sort of pin lock for safety. Be sure to tighten it pretty well when replacing the socket.

Function

Here are some functions of Rack and Pinion type of steering gearboxes –

1. The gearbox employs a rack (a toothed bar) and a pinion (a small gear). As the driver turns the steering wheel, the pinion engages with the teeth on the rack, causing it to move laterally.
2. Rack and Pinion steering gearboxes are often designed to be compact, making them suitable for a wide range of vehicles and fitting into the limited space in the engine compartment.
3. The design provides a mechanical advantage, allowing the driver to turn the steering wheel with less effort while still achieving the necessary force to control the vehicle.
4. The simplicity of the design and the reduction of moving parts contribute to the durability of Rack and Pinion steering gearboxes, making them reliable over the long term.
5. The quick and precise response of Rack and Pinion steering contributes to the vehicle’s overall handling characteristics, providing a more engaging driving experience.
6. The straightforward design of Rack and Pinion steering gearboxes often results in easier maintenance compared to more complex systems.

Conclusion on Types of Steering Gearboxes

In conclusion, the steering gearboxes are an important component in steering the vehicle with minimum rotational force. With minimum force and effort, the steering gearbox helps to rotate the wheel. In the steering gearbox, the rotational force converts into linear motion. So having the gearbox in steering is very important to drive the vehicle.

Frequently Asked Questions(FAQ’S)

What are the common types of steering gearboxes used in vehicles?

The common types of steering gearboxes used in vehicles include Rack and Pinion, Recirculating Ball, Cam and Roller, Worm and Sector, Worm and Ball Bearing Nut, and Cam and Double Lever steering gearboxes.

Why do we use a steering gearbox?

The primary function of a steering gearbox is to convert the rotary motion of the steering wheel into the lateral motion needed to turn the vehicle’s wheels. This conversion is necessary to provide a direct and controllable means for the driver to navigate the vehicle.