Information about Double Wishbone
In automobiles, a double wishbone (or "upper and lower A-arm") suspension is an independent suspension design using two parallel 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 double wishbone suspension is also often referred to as double 'A' arm or short long arm (SLA) suspension.
SLAs are very common on front suspensions for medium to large cars such as the Honda Accord or Chrysler 300, pickups, SUVs, and are very common on sports cars and racing cars.
A single wishbones or A-arms are used in various other suspension types, such as MacPherson strut and Chapman strut.
The suspension consists of a pair of upper and lower lateral arms, roughly horizontal. The upper arm is usually shorter to induce negative camber as the suspension jounces (rises). When the vehicle is in a turn, body roll results in positive camber gain on the outside wheel. The outside wheel also jounces and gains negative camber due to the short upper arm. The suspension designer attempts to balance these two effects to cancel out and keep the tire perpendicular to the ground. This is especially important for the outer tire because of the weight transfer to this tire during a turn.
Between the outboard end of the arms is a knuckle with a spindle or hub which carries the wheel bearing and wheel. Knuckles with an integral spindle usually do not allow the wheel to be driven. A bolt on hub design is commonly used if the wheel is to be driven.
In order to resist fore-aft loads such as acceleration and braking, the arms need two bushings or ball joints at the body.
At the knuckle end, single ball joints are typically used, in which case the steering loads have to be taken via a steering arm, and the wishbones look A- or L-shaped. An L-shaped arm is generally preferred on passenger vehicles because it allows a better compromise of handling and comfort to be tuned in. The bushing in line with the wheel can be kept relatively stiff to effectively handle cornering loads while the off-line joint can be softer to allow the wheel to recess under fore aft impact loads. For a rear suspension, a pair of joints can be used at both ends of the arm, making them more H-shaped in plain view.
In front view, the suspension is a 4-bar link, and it is easy to work out the camber gain (see camber angle) and other parameters for a given set of bush locations.
The various bushes do not have to be on horizontal axes, parallel to the vehicle centre line. If they are set at an angle, then antidive and antisquat can be dialed in.
The advantage of a double wishbone suspension is that it is fairly easy to work out the effect of moving each joint, so you can tune the kinematics of the suspension easily and optimize wheel motion. It is also easy to work out the loads that different parts will be subjected to which allows more optimized lightweight parts to be designed. They also provide increasing negative camber gain all the way to full jounce travel unlike the MacPherson strut which provides negative camber gain only at the beginning of jounce travel and then reverses into positive camber gain at high jounce amounts.
The disadvantage is that it is slightly more complex than other systems like a MacPherson strut.
Prior to the dominance of front wheel drive in the 1980s, many everyday cars used double wishbone front suspension systems, or a variation on it. Since that time, the MacPherson strut has become almost ubiquitous, as it is simpler and cheaper to manufacture. Double wishbones are usually considered to have superior dynamic characteristics, load handling capability and are still found on higher performance vehicles.
Honda Accord
Manufacturer Honda
Production 1976–present
Predecessor Honda 1300
Class Compact (1976–1993)
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Bearing may refer to:
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This article may contain original research or unverified claims.
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Double Wishbone Suspension
The double wishbone suspension is also often referred to as double 'A' arm or short long arm (SLA) suspension.
SLAs are very common on front suspensions for medium to large cars such as the Honda Accord or Chrysler 300, pickups, SUVs, and are very common on sports cars and racing cars.
A single wishbones or A-arms are used in various other suspension types, such as MacPherson strut and Chapman strut.
The suspension consists of a pair of upper and lower lateral arms, roughly horizontal. The upper arm is usually shorter to induce negative camber as the suspension jounces (rises). When the vehicle is in a turn, body roll results in positive camber gain on the outside wheel. The outside wheel also jounces and gains negative camber due to the short upper arm. The suspension designer attempts to balance these two effects to cancel out and keep the tire perpendicular to the ground. This is especially important for the outer tire because of the weight transfer to this tire during a turn.
Between the outboard end of the arms is a knuckle with a spindle or hub which carries the wheel bearing and wheel. Knuckles with an integral spindle usually do not allow the wheel to be driven. A bolt on hub design is commonly used if the wheel is to be driven.
In order to resist fore-aft loads such as acceleration and braking, the arms need two bushings or ball joints at the body.
At the knuckle end, single ball joints are typically used, in which case the steering loads have to be taken via a steering arm, and the wishbones look A- or L-shaped. An L-shaped arm is generally preferred on passenger vehicles because it allows a better compromise of handling and comfort to be tuned in. The bushing in line with the wheel can be kept relatively stiff to effectively handle cornering loads while the off-line joint can be softer to allow the wheel to recess under fore aft impact loads. For a rear suspension, a pair of joints can be used at both ends of the arm, making them more H-shaped in plain view.
In front view, the suspension is a 4-bar link, and it is easy to work out the camber gain (see camber angle) and other parameters for a given set of bush locations.
The various bushes do not have to be on horizontal axes, parallel to the vehicle centre line. If they are set at an angle, then antidive and antisquat can be dialed in.
The advantage of a double wishbone suspension is that it is fairly easy to work out the effect of moving each joint, so you can tune the kinematics of the suspension easily and optimize wheel motion. It is also easy to work out the loads that different parts will be subjected to which allows more optimized lightweight parts to be designed. They also provide increasing negative camber gain all the way to full jounce travel unlike the MacPherson strut which provides negative camber gain only at the beginning of jounce travel and then reverses into positive camber gain at high jounce amounts.
The disadvantage is that it is slightly more complex than other systems like a MacPherson strut.
Prior to the dominance of front wheel drive in the 1980s, many everyday cars used double wishbone front suspension systems, or a variation on it. Since that time, the MacPherson strut has become almost ubiquitous, as it is simpler and cheaper to manufacture. Double wishbones are usually considered to have superior dynamic characteristics, load handling capability and are still found on higher performance vehicles.
See also
control arm (sometimes called a wishbone or A-arm) is a nearly flat and roughly triangular member (or sub-frame), that pivots in two places. The broad end of the triangle attaches at the frame and pivots on a bushing.
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Independent suspension is a broad term for any automobile suspension system that allows each wheel on the same axle to move vertically (i.e. reacting to a bump in the road) independently of each other.
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Wishbone may refer to:
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- The wishbone, known in anatomy as the furcula, is a sternum bone found in birds which is shaped like the letter Y. It is used as an attachment point for the wing muscles.
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chassis (plural: "chassis") (IPA: /ˈʃæːsiː, ˈtʃæːsiː/) consists of a framework that supports an inanimate object, analogous to an animal's skeleton, for example in a motor vehicle or a
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A shock absorber in common parlance (or damper in technical use) is a mechanical device designed to smooth out or damp a sudden shock impulse and dissipate kinetic energy. It is analogous to a resistor in an electric RLC circuit.
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spring is a flexible elastic object used to store mechanical energy. Springs are usually made out of hardened steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication.
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Camber angle is the angle made by the wheel of an automobile; specifically, it is the angle between the vertical axis of the wheel and the vertical axis of the vehicle when viewed from the front or rear. It is used in the design of steering and suspension.
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caster angle for aesthetic reasons]]
Caster angle is the angular displacement from the vertical axis of the suspension of a steered wheel in a car, bicycle or other vehicle, measured in the longitudinal direction.
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Caster angle is the angular displacement from the vertical axis of the suspension of a steered wheel in a car, bicycle or other vehicle, measured in the longitudinal direction.
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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 and compliant effects. This can be contrasted with steer, which is the antisymmetric angle, i.e.
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The roll center of a vehicle is the notional point at which the cornering forces in the suspension are reacted to the vehicle body.
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Theory
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The scrub radius of a vehicle suspension is the distance between the steer axis of the suspension where it strikes the ground, and the centre of the contact patch, in front view.
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Honda Accord
Manufacturer Honda
Production 1976–present
Predecessor Honda 1300
Class Compact (1976–1993)
..... Click the link for more information.
control arm (sometimes called a wishbone or A-arm) is a nearly flat and roughly triangular member (or sub-frame), that pivots in two places. The broad end of the triangle attaches at the frame and pivots on a bushing.
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MacPherson strut is a type of car suspension system widely used in modern vehicles, named after Earl S. MacPherson who developed the design. Though named for him, it was actually invented by an engineer named Fornaca at FIAT in the mid-1920s.
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Chapman strut is an automobile suspension device. Being a strut, it is designed to act as both a shock absorber (with an integrated coil spring) and a wheel location device. That is, it is designed to resist lateral forces.
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Not to be confused with Bering or Baring.
Bearing may refer to:
- Bearing (navigation), a term for direction
- Bearing (mechanical), a component that separates moving parts and takes a load
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brake is a device for slowing or stopping the motion of a machine or vehicle, or alternatively a device to restrain it from starting to move again. The kinetic energy lost by the moving part is usually translated to heat by friction.
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bushing is a cylindrical lining designed to reduce friction and wear, or constrict and restrain motion of mechanical parts.
In the electrical field bushings are circular plastic ring fittings that slide or screw onto conduit or connectors to provide protection to the
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In the electrical field bushings are circular plastic ring fittings that slide or screw onto conduit or connectors to provide protection to the
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Camber angle is the angle made by the wheel of an automobile; specifically, it is the angle between the vertical axis of the wheel and the vertical axis of the vehicle when viewed from the front or rear. It is used in the design of steering and suspension.
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Kinematics (Greek κινειν,kinein, to move) is a branch of mechanics which describes the motion of objects without the consideration of the masses or forces that bring about the motion.
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MacPherson strut is a type of car suspension system widely used in modern vehicles, named after Earl S. MacPherson who developed the design. Though named for him, it was actually invented by an engineer named Fornaca at FIAT in the mid-1920s.
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MacPherson strut is a type of car suspension system widely used in modern vehicles, named after Earl S. MacPherson who developed the design. Though named for him, it was actually invented by an engineer named Fornaca at FIAT in the mid-1920s.
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Front-wheel drive is a form of engine/transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longitudinal engine arrangement generally found in
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MacPherson strut is a type of car suspension system widely used in modern vehicles, named after Earl S. MacPherson who developed the design. Though named for him, it was actually invented by an engineer named Fornaca at FIAT in the mid-1920s.
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An SLA is also known as an unequal length double wishbone suspension. The upper arm is typically an A-arm, and is shorter than the lower link, which is an A-arm or an L-arm, or sometimes a pair of tension/compression arms.
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strut bar or strut brace is a mostly aftermarket car suspension accessory used in conjunction with MacPherson struts on monocoque or unibody chassis to provide extra strength between the strut towers.
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A Torsion beam Suspension, also known as a torsion bar
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A Torsion beam Suspension, also known as a torsion bar
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A dual ball joint suspension uses a pair of arms, one in tension, one in compression, to replace a wishbone, in a MacPherson or SLA suspension. The outer end of each arm terminates in a ball joint, hence the name.
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