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).
A tie rod or tie bar is a slender structural unit used as a tie and capable of carrying tensile loads only. It is any rod or bar-shaped structural member designed to prevent the separation of two parts, as in a vehicle.
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 locomotion.
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. 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, later followed by the Mercedes 130H/150H/170H, the Standard Superior, the Volkswagen Beetle and 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.
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 Chevrolet Engineering Research Vehicle (CERV) is a series of Chevrolet experimental cars. Chevrolet Staff engineer, designer, and race car driver Zora Arkus-Duntov started development of the CERV I in 1959, and began work on the CERV II in 1963. Chevrolet chief engineer Don Runkle and Lotus' Tony Rudd discussed creating a new show car to demonstrate their engineering expertise in 1985; It would become the CERV III. Corvette chief engineer Dave Hill unveiled the CERV IV in 1993, a test vehicle for the 1997 C5 Corvette.
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.
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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