Steering is the term applied to the collection of components, linkages, etc. which will allow for a vessel (ship, boat) or vehicle (car) to follow the desired course. A ship /ʃɪp/ is a large vessel that floats on water Ships are generally distinguished from Boats based on size A boat is a Watercraft of modest size designed to float or plane on water and provide transport over it Vehicles, derived from the Latin word vehiculum, are non-living Means of transport. An exception is the case of rail transport by which rail tracks combined together with railroad switches provide the steering function. "Railroad" and "Railway" both redirect here For other uses see Railroad (disambiguation. This article primarily uses North American terminology British and Commonwealth terms are given in parentheses

Part of steering mechanism: tie rod, steering arm, king pin.

Introduction

The most conventional steering arrangement is to turn the front wheels using a hand–operated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal joints to allow it to deviate somewhat from a straight line. A wheel is a circular device that is capable of rotating on its axis facilitating movement or transportation whilst supporting a load ( Mass) or performing labour in machines A steering wheel (also called a driving wheel or hand wheel) is a type of steering Control in Vehicles and vessels ( Ships and Boats The automotive steering column is a device intended primarily for connecting the Steering wheel to the steering mechanism by transferring the driver's input torque from A universal joint, U joint, Cardan joint, Hardy- Spicer joint, or Hooke's joint is a Other arrangements are sometimes found on different types of vehicles, for example, a tiller or rear–wheel steering. A tiller or till is a Lever attached to a Rudder post (American terminology or Rudder stock (English terminology of a boat in order to provide Tracked vehicles such as tanks usually employ differential steering — that is, the tracks are made to move at different speeds or even in opposite directions to bring about a change of course. A tracked vehicle (also called track-type tractor tractor crawler or track-laying vehicle is a vehicle that runs on tracks instead of Wheels Typically used

Rack and pinion, recirculating ball, worm and sector

Rack and pinion animation

Rack and pinion unit mounted in the cockpit of an Ariel Atom sports car chassis. The Ariel Atom is a high performance sports car made by the Ariel Motor Company based in Somerset, England. For most high volume production, this is usually mounted on the other side of this panel

Many modern cars use rack and pinion steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a sort of linear gear which meshes with the pinion, from side to side. A rack and pinion is a pair of Gears which convert rotational motion into linear motion This motion applies steering torque to the kingpins of the steered wheels via tie rods and a short lever arm called the steering arm. A torque (τ in Physics, also called a moment (of force is a pseudo- vector that measures the tendency of a force to rotate an object about The kingpin is the main Pivot in the steering mechanism of a car or other Vehicle. A tie rod is a slender structural rod used as a tie and (in most applications capable of carrying tensile loads only

The rack and pinion design has the advantages of a large degree of feedback and direct steering "feel"; it also does not normally have any backlash, or slack. In Mechanical engineering, backlash, sometimes called lash or play, is clearance between mating components sometimes described as the amount of lost A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.

Older designs often use the recirculating ball mechanism, which is still found on trucks and utility vehicles. Recirculating ball, also known as recirculating ball and nut or worm and sector, is a Steering mechanism commonly found in older cars and This is a variation on the older worm and sector design; the steering column turns a large screw (the "worm gear") which meshes with a sector of a gear, causing it to rotate about its axis as the worm gear is turned; an arm attached to the axis of the sector moves the pitman arm, which is connected to the steering linkage and thus steers the wheels. A worm drive is a gear arrangement in which a worm (which is a gear in the form of a screw) meshes with a worm gear (which is A mechanical linkage is a series of rigid links connected with joints to form a closed chain or a series of closed chains The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the teeth of the worm and those of the screw; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are "recirculated".

The recirculating ball mechanism has the advantage of a much greater mechanical advantage, so that it was found on larger, heavier vehicles while the rack and pinion was originally limited to smaller and lighter ones; due to the almost universal adoption of power steering, however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars. In Physics and Engineering, mechanical advantage (MA is the factor by which a mechanism multiplies the force put into it Power steering is a system for reducing the Steering effort on vehicles by using an external power source to assist in turning the roadwheels. The recirculating ball design also has a perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus; this is easily adjustable via a screw on the end of the steering box to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage. The much smaller degree of feedback with this design can also sometimes be an advantage; drivers of vehicles with rack and pinion steering can have their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick to one side suddenly (leading to driving instructors telling students to keep their thumbs on the front of the steering wheel, rather than wrapping around the inside of the rim). This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering prevents this degree of feedback, just as it prevents desirable feedback under normal circumstances.

The steering linkage connecting the steering box and the wheels usually conforms to a variation of Ackermann steering geometry, to account for the fact that in a turn, the inner wheel is actually traveling a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path is not suitable for turns. Ackermann steering geometry is a geometric arrangement of linkages in the Steering of a car or other Vehicle designed to solve the problem of wheels on In Automotive engineering, toe is the symmetric Angle that each wheel makes with the longitudinal axis of the vehicle as a function of static geometry and kinematic

The worm and sector was an older design, used for example in Willys and Chrysler vehicles, and the Ford Falcon (1960's). ^[1][2]

Power steering

Main article: Power steering

As vehicles have become heavier and switched to front wheel drive, the effort to turn the steering wheel manually has increased - often to the point where major physical exertion is required. Power steering is a system for reducing the Steering effort on vehicles by using an external power source to assist in turning the roadwheels. Front-wheel drive (or FF layout) is a form of engine / transmission layout used in Motor vehicles where the engine drives the front Wheels To alleviate this, auto makers have developed power steering systems. The automotive industry is the industry involved in the design development manufacture marketing and sale of Motor vehicles In 2007 more than 73 million motor vehicles Power steering is a system for reducing the Steering effort on vehicles by using an external power source to assist in turning the roadwheels. There are two types of power steering systems—hydraulic and electric/electronic. There is also a hydraulic-electric hybrid system possible.

A hydraulic power steering (HPS) uses hydraulic pressure supplied by an engine-driven pump to assist the motion of turning the steering wheel. Electric power steering (EPS) is more efficient than the hydraulic power steering, since the electric power steering motor only needs to provide assistance when the steering wheel is turned, whereas the hydraulic pump must run constantly. Electric power steering ( EPS or EPAS) is designed to use an Electric motor to reduce effort by providing assist to the driver of a Vehicle In EPS the assist level is easily tunable to the vehicle type, road speed, and even driver preference. An added benefit is the elimination of environmental hazard posed by leakage and disposal of hydraulic power steering fluid.

Speed Adjustable Steering

An outgrowth of power steering is speed adjustable steering, where the steering is heavily assisted at low speed and lightly assisted at high speed. The auto makers perceive that motorists might need to make large steering inputs while manoeuvering for parking, but not while traveling at high speed. The first vehicle with this feature was the Citroën SM with its Diravi layout, although rather than altering the amount of assistance as in modern power steering systems, it altered the pressure on a centring cam which made the steering wheel try to "spring" back to the straight-ahead position. The Citroën SM was a high performance Coupé produced by the French manufacturer Citroën between 1970 and 1975 DIRAVI is the name given by Citroën to its proprietary Power steering system first seen in 1970 Modern speed-adjustable power steering systems reduce the pressure fed to the ram as the speed increases, giving a more direct feel. This feature is gradually becoming commonplace across all new vehicles.

Four-wheel steering

Four-wheel steering (or all wheel steering) is a system employed by some vehicles to improve steering response, increase vehicle stability while maneuvering at high speed, or to decrease turning radius at low speed. The turning radius or turning circle of a Vehicle is the Radius of the smallest circular turn (ie

In most active four-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the front wheels. Some systems, including Delphi's Quadrasteer and the system in Honda's Prelude line, allow for the rear wheels to be steered in the opposite direction as the front wheels during low speeds. Quadrasteer is the name of a 4-wheel steering system developed by Delphi Corporation while under the ownership of General Motors for use in automobiles This allows the vehicle to turn in a significantly smaller radius — sometimes critical for large trucks or vehicles with trailers. A pickup truck is a light Motor vehicle with an open-top rear cargo area which is almost always separated from the cab to allow for chassis flex when carrying or pulling

Many modern vehicles offer a form of passive rear steering to counteract normal vehicle tendencies. For example, Subaru used a passive steering system to correct for the rear wheel's tendency to toe-out. On many vehicles, when cornering, the rear wheels tend to steer slightly to the outside of a turn, which can reduce stability. The passive steering system uses the lateral forces generated in a turn (through suspension geometry) and the bushings to correct this tendency and steer the wheels slightly to the inside of the corner. A mechanical bushing is a cylindrical lining designed to reduce friction and wear inside a hole or constrict and restrain motion of mechanical parts This improves the stability of the car, through the turn. This effect is called compliance understeer and it, or its opposite, is present on all suspensions. Understeer is a term for a Car handling condition in which during cornering the circular path of the Vehicle 's motion is of a greater radius than the circle indicated Typical methods of achieving compliance understeer are to use a Watt's Link on a live rear axle, or the use of toe control bushings on a twist beam suspension. On an independent rear suspension it is normally achieved by changing the rates of the rubber bushings in the suspension. Independent suspension is a broad term for any Automobile suspension system that allows each wheel on the same Axle to move vertically (i Some suspensions will always have compliance oversteer due to geometry, such as Hotchkiss live axles or a semi trailing arm IRS. Oversteer is a phenomenon that can occur in an Automobile which is attempting to turn

Recent application

In an active 4ws system all four wheels turn at the same time when you steer. There can be controls to switch off the rear steer and options to steer only the rear wheel independent of the front wheels. At slow speeds (e. g. parking) the rear wheels turn opposite of the front wheels, reducing the turning radius by up to twenty-five percent, while at higher speeds both front and rear wheels turn alike (electronically controlled), so that the vehicle may change position with less yaw, enhancing straight-line stability. The yaw angle is the angle between a vehicle's heading and a reference heading (normally true or magnetic North) The "Snaking effect" experienced during motorway drives while towing a caravan is thus largely nullified. Motorway is a term for both a type of Road and a classification or designation A travel trailer or caravan is a trailer towed behind a road Vehicle to provide a place to sleep which is more comfortable and protected than a Four-wheel steering found its most widespread use in monster trucks, where maneuverability in small arenas is critical, and it is also popular in large farm vehicles and trucks. A monster truck is an Automobile, typically styled after Pickup trucks modified or purposely built with extremely large Wheels and suspension. A farm is an area of land including various structures devoted primarily to the practice of producing and managing food ( Produce, Grains, or Livestock This article is about the semi-truck For the North American use of the word see Pickup truck.

General Motors offers Delphi's Quadrasteer in their consumer Silverado/Sierra and Suburban/Yukon. General Motors Corporation ( GM) ( is a multinational automobile manufacturer founded in 1908 and headquartered in the United States. Delphi is an Automotive parts company headquartered in Troy Michigan, USA. Quadrasteer is the name of a 4-wheel steering system developed by Delphi Corporation while under the ownership of General Motors for use in automobiles The Chevrolet Silverado (along with its GMC counterpart the GMC Sierra) is the latest line of Full-size Pickup trucks from General The Chevrolet Silverado (along with its GMC counterpart the GMC Sierra) is the latest line of Full-size Pickup trucks from General The Chevrolet Suburban is a large Sport utility vehicle from Chevrolet. However, only 16,500 vehicles have been sold with this system since its introduction in 2002 through 2004. See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Due to this low demand, GM will not offer the technology on the 2007 update to these vehicles. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.

Previously, Honda had four-wheel steering as an option in their 1987-2000 Prelude, and Mazda also offered four-wheel steering on the 626 and MX6 in 1988. () is a Multinational corporation, engine Manufacturer and engineering corporation headquartered in Japan. Year 1987 ( MCMLXXXVII) was a Common year starting on Thursday (link displays 1987 Gregorian calendar) 2000 ( MM) was a Leap year that started on Saturday of the Common Era, in accordance with the Gregorian calendar. The Honda Prelude was a sports Coupe Japanese automaker Honda from 1978 through 2001 ( is a Japanese automotive manufacturer based in Hiroshima, Japan. The Mazda 626 was an Automobile produced by Mazda for the export market The Mazda MX-6 was a Front-wheel drive sporty coupe produced by Mazda between 1987 and 1997 Year 1988 ( MCMLXXXVIII) was a Leap year starting on Friday (link displays 1988 Gregorian calendar) Neither system was very popular, in that whatever improvement they brought to these already excellent-handling vehicles was offset by an unavoidable decrease in sensitivity caused by the increased weight and complexity.

A new "Active Drive" system is introduced on the 2008 version of the Renault Laguna line. The Renault Laguna is a Large family car produced by the French manufacturer Renault. It was designed as one of several measures to increase security and stability. The Active Drive should lower the effects of under steer and decrease the chances of spinning by diverting part of the G-forces generated in a turn from the front to the rear tires. At low speeds the turning circle can be tightened so parking and maneuvering is easier.

Production cars with active four wheel steering

Articulated steering

A front loader with articulated steering. The Toyota Celica name has been applied to a series of popular Coupes made by the Japanese company Toyota. The Toyota Soarer was a personal luxury GT Coupé sold by Toyota in Japan from 1981 to 2004 A loader is a type of construction equipment (engineering vehicle machinery that is primarily used to "load" material (asphalt demolition debris

Articulated steering is a system by which a four-wheel drive vehicle is split into front and rear halves which are connected by a vertical hinge. The front and rear halves are connected with one or more hydraulic cylinders that change the angle between the halves, including the front and rear axles and wheels, thus steering the vehicle. A Hydraulic cylinder (also called a linear Hydraulic motor) is a mechanical Actuator that is used to give a linear Force through a linear stroke This system does not use steering arms, king pins, tie rods, etc. as does four-wheel steering. If the vertical hinge is placed equidistant between the two axles, it also eliminates the need for a central differential, as both front and rear axles will follow the same path, and thus rotate at the same speed. This article deals with the concept of a differential in mechanical engineering.

SuperSteer

SuperSteer is used by NewHolland to make tractors turning radius smaller. The SuperSteer front axle articulates when the wheels turn. The inside wheel moves away from the frame, while the outside wheel moves in front of the bumper/nose of the tractor, providing more tire clearance and a greater turn angle. A picture of this turning action can be seen here.

Steer-By-Wire

The aim of steer-by-wire technology is to completely do away with as many mechanical components (steering shaft, column, gear reduction mechanism, etc. Drive-by-wire, DbW, by-wire, or x-by-wire technology in the automotive industry replaces the traditional mechanical and hydraulic Control systems ) as possible. Completely replacing conventional steering system with steer-by-wire holds several advantages, such as:

• The absence of steering column simplifies the car interior design.

• The absence of steering shaft, column and gear reduction mechanism allows much better space utilization in the engine compartment.

• The steering mechanism can be designed and installed as a modular unit.

• Without mechanical connection between the steering wheel and the road wheel, it is less likely that the impact of a frontal crash will force the steering wheel to intrude into the driver's survival space.

• Steering system characteristics can easily and infinitely be adjusted to optimize the steering response and feel.

As of 2007 there are no production cars available that rely solely on steer-by-wire technology due to safety and reliability concerns, but this technology has been demonstrated in numerous concept cars.

Safety

For safety reasons all modern cars feature a collapsible steering column (energy absorbing steering column) which will collapse in the event of a heavy frontal impact to avoid excessive injuries to the driver. Non-collapsible steering columns very often impaled drivers in frontal crashes. Impalement is a term that refers to situations in which objects are driven through the body causing deep stabbing wounds Audi has a retractable wheel system called procon-ten. AUDI AG, ( Xetra: NSU commonly known as Audi (aˈʊdi is a German Automobile manufacturer which produces Audi branded cars with headquarters procon-ten (lower case initial "p") (an acronym for Pro grammed Con traction- Ten sion) is a Proprietary

Collapsible steering columns were invented by Bela Barenyi. Béla Barényi ( 1 March 1907 &ndash 30 May 1997) was a Hungarian - Austrian engineer regarded as the father of Passive

This safety feature first appeared on cars built by General Motors after an extensive and very public lobbying campaign enacted by Ralph Nader. General Motors Corporation ( GM) ( is a multinational automobile manufacturer founded in 1908 and headquartered in the United States. Lobbying includes all attempts to influence Legislators and officials whether by other legislators constituents or organized groups Ralph Nader (born February 27 1934 is an American Attorney, Author, Lecturer, political activist, and independent candidate for President

Ford started to install collapsible steering columns in 1968. Ford Motor Company is an American Multinational corporation and the world's fourth largest automaker based on Worldwide vehicle sales, following ^[4]

Cycles

Steering is crucial to the stability of bicycles and motorcycles. For details, see articles on bicycle and motorcycle dynamics and countersteering. Bicycle and motorcycle dynamics is the Science of the motion of Bicycles and Motorcycles and their components due to the Forces acting Countersteering is the technique used by cyclists and motorcyclists to initiate turning toward a given direction by first steering counter to the desired direction

See also

External links

• How Car Steering Works (HowStuffWorks.com)
• High Quality Steering System Repairs Guide
• What is Camber & how to correct it

References

• Encyclopedia of German Tanks of World War Two by Peter Chamberlain and Hilary Doyle, 1978, 1999