Rack and pinion in the context of "Lock gate"

A steering wheel (also called a driving wheel, a hand wheel, or simply wheel) is a type of steering control in vehicles.

Steering wheels are used in most modern land vehicles, including all mass-production automobiles, buses, light and heavy trucks, as well as tractors and tanks. The steering wheel is the part of the steering system that the driver manipulates; the rest of the steering system responds to such driver inputs. This can be through direct mechanical contact as in recirculating ball or rack and pinion steering gears, without or with the assistance of hydraulic power steering, HPS, or as in some modern production cars with the help of computer-controlled motors, known as electric power steering.

A gear or gearwheel, also called a toothed wheel, is a rotating machine part typically used to transmit rotational motion or torque by means of a series of "teeth" that engage with compatible teeth of another gear or other part. The teeth can be integral saliences or cavities machined on the part, or separate pegs inserted into it. In the latter case, the gear is usually called a cogwheel. A cog may be one of those pegs or the whole gear. Two or more meshing gears are called a gear train.

The smaller member of a pair of meshing gears is often called pinion. Most commonly, gears and gear trains can be used to trade torque for rotational speed between two axles or other rotating parts or to change the axis of rotation or to invert the sense of rotation. A gear may also be used to transmit linear force or linear motion to a rack, a straight bar with a row of compatible teeth.

Recirculating ball, also known as recirculating ball and nut or worm and sector, is a ball screw steering mechanism commonly found in older automobiles, off-road vehicles, and some trucks. Most newer cars use the more economical rack and pinion steering instead, but some upmarket manufacturers (such as BMW and Mercedes-Benz) held on to the design until well into the 1990s for the durability and strength inherent in the design. A few, including Chrysler, General Motors, Lada and Ineos, still use this technology in certain models including the Jeep Wrangler, the Ineos Grenadier Quartermaster and the Lada Niva.

A rack railway (also rack-and-pinion railway, cog railway, or cogwheel railway) is a steep grade railway with a toothed rack rail, usually between the running rails. The trains are fitted with one or more cog wheels or pinions that mesh with this rack rail. This allows the trains to operate on steep gradients of 100% (45 degrees) or more, well above the 10% (5.7 degrees) maximum for friction-based rail. The rack and pinion mechanism also provides more controlled braking and reduces the effects of snow or ice on the rails. Most rack railways are mountain railways, although a few are transit railways or tramways built to overcome a steep gradient in an urban environment.The first cog railway was the Middleton Railway between Middleton and Leeds in West Yorkshire, England, United Kingdom, where the first commercially successful steam locomotive, Salamanca, ran in 1812. This used a rack and pinion system designed and patented in 1811 by John Blenkinsop.

The first mountain cog railway was the Mount Washington Cog Railway in the U.S. state of New Hampshire, which carried its first fare-paying passengers in 1868. The track was completed to reach the summit of Mount Washington in 1869. The first mountain rack railway in continental Europe was the Vitznau-Rigi-Bahn on Mount Rigi in Switzerland, which opened in 1871. Both lines are still running.

The Citroën Traction Avant (French pronunciation: [tʁaksjɔnaˈvɑ̃]) is the world's first mass-produced, semi-monocoque bodied, front-wheel drive car. A range of mostly four-door saloons and executive cars, as well as longer wheelbased "Commerciale", and three row seating "Familiale" models, were produced with four- and six-cylinder engines, by French carmaker Citroën from 1934 to 1957. With some 760,000 units built, the Traction Avants were the first front-wheel drives made in such (six-figure) quantity.

Whilst front-wheel drive and four-wheel independent suspension had been established in production cars by Auto Union, and subsequently by others a few years prior – the Traction Avant pioneered integrating these into a mass-production car with a crash resistant, largely unitary, monocoque body. Additionally, the car was also an early adopter of rack and pinion steering.

A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a chain, rack or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth except for timing pulleys used with toothed belts.

Sprockets are used in bicycles, motorcycles, tracked vehicles, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a track, tape etc. Perhaps the most common form of sprocket may be found in the bicycle, in which the pedal shaft carries a large sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the rear wheel. Early automobiles were also largely driven by sprocket and chain mechanism, a practice largely copied from bicycles.