A drag link converts rotary motion from a crank arm, to a second bellcrank, usually in an automotive steering system.
While the origin of the term is not clear, it pre-dates the automobile, and is described as in use in 1849 as a means of rotating a Ducie cultivator being operated by cable by stationary steam engine (or between engines). [1]
The term is commonly used in automotive technology for the link in steering linkage that connects the drop arm (also called pitman arm) on the steering box to a steering arm which causes the wheels to steer the vehicle. Normally the drop link connects to one wheel which is connected to the other wheel by a track rod (or tie rod) which is an adjustable rod which determines the relative wheel alignment. [2]
Typically, one end of the drag link is connected via the drop arm and steering gearbox to the steering wheel (providing the connection between the driver and the steering system); the other end is attached to one of the wheels by the steering arm.
An alternate steering mechanism is a rack and pinion, a three bar linkage that eliminates the drag link by directly moving a center link.
"The drag link connects the pitman arm to the steering arm, or in some applications it connects to the tie rod assembly. Unlike a center link, the drag link does not connect to an idler arm, and has no inner tie rod ends attached to it. On some applications the drag link swings from the front to the rear of the vehicle. On these applications the drag link connects to the steering arm located at the wheel. In some Jeep applications, the drag link will swing from right to left on the vehicle and will connect to the steering arm at the wheel. Drag links can be a solid one-piece design or an adjustable design. Many drag links have replaceable or rebuildable ends." [3]
Wear in the joints at the end of the drag link in a steering system will result in play in the steering. It will not affect the wheel alignment as that is determined by the track rod (tie rod in USA).
The 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 the inside and outside of a turn needing to trace out circles of different radii.
Steering is the control of the direction of motion or the components that enable its control. Steering is achieved through various arrangements, among them ailerons for airplanes, rudders for boats, cylic tilting of rotors for helicopters, and many more.
Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/handling and ride quality, which are at odds with each other. The tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.
Rail transport terms are a form of technical terminology applied to railways. Although many terms are uniform across different nations and companies, they are by no means universal, with differences often originating from parallel development of rail transport systems in different parts of the world, and in the national origins of the engineers and managers who built the inaugural rail infrastructure. An example is the term railroad, used in North America, and railway, generally used in English-speaking countries outside North America and by the International Union of Railways. In English-speaking countries outside the United Kingdom, a mixture of US and UK terms may exist.
A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.
A swing axle is a simple type of independent suspension designed and patented by Edmund Rumpler in 1903 for the rear axle of rear wheel drive vehicles. This was a revolutionary invention in automotive suspension, allowing driven (powered) wheels to follow uneven road surfaces independently, thus enabling the vehicle's wheels to maintain better road contact and holding; plus each wheel's reduced unsprung weight means their movements have less impact on the vehicle as a whole. The first automotive application was the Rumpler Tropfenwagen, another early example was the 1923 Tatra 11 later followed by the Mercedes 130H/150H/170H, the Standard Superior, the pre-facelift Volkswagen Beetle and most of its derivatives, the Chevrolet Corvair, and the roll-over prone M151 jeep amongst others.
A Pitman arm is a shaft that translates rotary or angular movement into linear movement, or vice versa. Pitman arms are commonly found in water pumping windmills, automotive steering systems, and sewing machines.
A crankpin or crank pin, also known as a rod bearing journal, is a mechanical device in an engine which connects the crankshaft to the connecting rod for each cylinder. It has a cylindrical surface, to allow the crankpin to rotate relative to the "big end" of the connecting rod.
A beam axle, rigid axle, or solid axle is a dependent suspension design in which a set of wheels is connected laterally by a single beam or shaft. Beam axles were once commonly used at the rear wheels of a vehicle, but historically, they have also been used as front axles in four-wheel-drive vehicles. In most automobiles, beam axles have been replaced with front (IFS) and rear independent suspensions (IRS).
In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles, and are used on virtually every automobile made. They bionically resemble the ball-and-socket joints found in most tetrapod animals.
The following outline is provided as an overview of and topical guide to automobiles:
Bump steer is the term for the tendency of the wheel of a car to steer itself as it moves through the suspension stroke.
The twist-beam rear suspension is a type of automobile suspension based on a large H- or C-shaped member. The front of the H attaches to the body via rubber bushings, and the rear of the H carries each stub-axle assembly, on each side of the car. The cross beam of the H holds the two trailing arms together, and provides the roll stiffness of the suspension, by twisting as the two trailing arms move vertically, relative to each other.
Transverse leaf spring front suspension is a type of automotive front suspension, whose usage is most well known in Ford Motor Company products from 1908 to 1948. "Suicide front axle" is a term that has been used for it.
A parallelogram steering linkage is called such because like its namesake, the two sides of the linkage run parallel to each other and are equal in distance. This type of steering linkage uses four tie rods, one inner and one outer on each side that are connected by an adjustment sleeve, a center link, an idler arm on the passenger side, and a pitman arm on the driver side. The pitman arm attaches to the steering gear output shaft which is also commonly called the pitman shaft. The pitman arm attaches to the center link and is moved by turning the steering wheel. The center link bar transfers the movement from the pitman arm and pitman shaft to the idler arm on the passenger side. The inner tie rods are mounted to the center link and transfer steering motion to the steering arms and outer tie rods. All of the joints which mount these components are constructed of small ball and socket joints to provide the necessary freedom of movement required to maintain control over the vehicle while it is in motion. The most common type of steering is the parallelogram. The cross-steer and Haltenberger linkage designs are used on some trucks and vans.
A steering linkage is the part of an automotive steering system that connects to the front wheels.
A slider-crank linkage is a four-link mechanism with three revolute joints and one prismatic (sliding) joint. The rotation of the crank drives the linear movement of the slider, or the expansion of gases against a sliding piston in a cylinder can drive the rotation of the crank.
Pull-rod suspension and push-rod suspension refer to a specialised type of automotive suspension system which is largely based on a double-wishbone system, incorporating elements of the commonly used MacPherson strut.
This glossary of automotive terms is a list of definitions of terms and concepts related to automobiles, including their parts, operation, and manufacture, as well as automotive engineering, auto repair, and the automotive industry in general. For more specific terminology regarding the design and classification of various automobile styles, see Glossary of automotive design; for terms related to transportation by road, see Glossary of road transport terms; for competitive auto racing, see Glossary of motorsport terms.
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