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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).
With a beam axle, the camber angle between the wheels is the same regardless of its location in the travel of the suspension.
A beam axle's location in the fore and aft directions is constrained by one of several suspension components, including trailing arms, semi-trailing arms, radius rods, and leaf springs. The lateral location can be constrained by a Panhard rod, a Scott Russell linkage, a Watt's linkage, or some other arrangement, most commonly by the leaf springs. Shock absorbers and either leaf springs, coil springs, or air bags are used to control vertical movement.
A live axle is a type of beam axle in which the shaft (or, commonly, shafts connected to move as a single unit) also transmits power to the wheels; a beam axle that does not also transmit power is sometimes called a dead axle. While typically used in vehicles with Hotchkiss drive, this suspension system can also be used with other types of power transmission.
An axle truss is typically a six-millimeter thick steel plate bent into a "Π"-shaped beam and welded with the open side facing the top of the differential or axle housing. It reinforces a solid axle so that it does not bend or break when the axle's load rating is exceeded. [4] A larger/thicker axle is stronger, but also comes with increased cost, unsprung weight, and more compatibility issues (drivetrain, suspension, steering geometries, body mount locations, clearances) on smaller vehicles. [5]
eAxle or E-axle is a solid axle with electric motors attached to the differential, either end, or elsewhere. Inverters, power electronics, gearboxes, transfer cases (including low-range gearing), and transmissions may also be attached to the motors and/or axle. All components move with the axle as unsprung weight. [6] [7] [8] [9]
An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a spindle.
The unsprung mass of a vehicle is the mass of the suspension, wheels or tracks, and other components directly connected to them. This contrasts with the sprung mass supported by the suspension, which includes the body and other components within or attached to it. Components of the unsprung mass include the wheel axles, wheel bearings, wheel hubs, tires, and a portion of the weight of driveshafts, springs, shock absorbers, and suspension links. Brakes that are mounted inboard are part of a vehicle's sprung mass.
Camber angle is one of the angles made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of a wheel and the vertical axis of the vehicle when viewed from the front or rear. It is used in the creation of steering and suspension. If the top of the wheel is farther out than the bottom, it is called positive camber; if the bottom of the wheel is farther out than the top, it is called negative camber.
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, tilting 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.
Independent suspension is any automobile suspension system that allows each wheel on the same axle to move vertically independently of the others. This is contrasted with a beam axle or deDion axle system in which the wheels are linked. "Independent" refers to the motion or path of movement of the wheels or suspension. It is common for the left and right sides of the suspension to be connected with anti-roll bars or other such mechanisms. The anti-roll bar ties the left and right suspension spring rates together but does not tie their motion together.
Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly during cornering, acceleration, and braking as well as on the vehicle's directional stability when moving in steady state condition.
In automotive design, a front-engine, front-wheel-drive (FWD) layout, or FF layout, places both the internal combustion engine and driven roadwheels at the front of the vehicle.
A double wishbone suspension is an independent suspension design for automobiles using two wishbone-shaped arms to locate the wheel. Each wishbone or arm has two mounting points to the chassis and one joint at the knuckle. The shock absorber and coil spring mount to the wishbones to control vertical movement. Double wishbone designs allow the engineer to carefully control the motion of the wheel throughout suspension travel, controlling such parameters as camber angle, caster angle, toe pattern, roll center height, scrub radius, scuff, and more.
The caster angle or castor angle is the angular displacement of the steering axis from the vertical axis of a steered wheel in a car, motorcycle, bicycle, other vehicle or a vessel, as seen from the side of the vehicle. The steering axis in a car with dual ball joint suspension is an imaginary line that runs through the center of the upper ball joint to the center of the lower ball joint, or through the center of the kingpin for vehicles having a kingpin.
In automotive engineering, toe, also known as tracking, is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with steer, which is the antisymmetric angle, i.e. both wheels point to the left or right, in parallel (roughly). Negative toe, or toe out, is the front of the wheel pointing away from the centreline of the vehicle. Positive toe, or toe in, is the front of the wheel pointing towards the centreline of the vehicle. Historically, and still commonly in the United States, toe was specified as the linear difference of the distance between the two front-facing and rear-facing tire centerlines at the outer diameter and axle-height; since the toe angle in that case depends on the tire diameter, the linear dimension toe specification for a particular vehicle is for specified tires.
A swing axle is a simple type of independent suspension, almost always for the rear axles, 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 de Dion axle is a form of non-independent automobile suspension. It is a considerable improvement over the swing axle, Hotchkiss drive, or live axle. Because it plays no part in transmitting power to the drive wheels, it is sometimes called a "dead axle".
Wheel alignment, which is sometimes referred to as breaking or tracking, is part of standard automobile maintenance that consists of adjusting the angles of wheels to the car manufacturer specifications. The purpose of these adjustments is to reduce tire wear and to ensure that vehicle travel is straight and true. Alignment angles can also be altered beyond the maker's specifications to obtain a specific handling characteristic. Motorsport and off-road applications may call for angles to be adjusted well beyond normal, for a variety of reasons.
Fishtailing is a vehicle handling problem which occurs when the rear wheels lose traction, resulting in oversteer. This can be caused by low-friction surfaces. Rear-drive vehicles with sufficient power can induce this loss of traction on any surface, which is called power-oversteer.
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.
An H-drive drivetrain is a system used for heavy off-road vehicles with 6×6 or 8×8 drive to supply power to each wheel station.
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.
