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27-443: The EMP2 platform is highly modular, with a choice of short and long wheelbase, low or high riding height, and a choice of independent multi-link or twisted-beam rear suspension. Comparing to the predecessor PF2 , the platform reduces the weight by 70 kg using very high strength steel , aluminum and magnesium alloys, and composite materials. This platform was first used on the second-generation Citroën C4 Picasso and then on

54-420: A trailing arm , control arm or wishbone , which has two bushings at one end. On a front suspension one of the lateral arms is replaced by the tie-rod , which connects the rack or steering box to the wheel hub. In order to simplify understanding, it is usual to consider the function of the arms in each of three orthogonal planes: The arms have to control toe /steer and lateral compliance. This needs

81-430: 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 plan view. Alternatively, a fixed-length driveshaft can perform

108-440: A pair of arms longitudinally separated. The arms have to control camber , particularly the way that the camber changes as the wheel moves up (into jounce, or bump) and down into rebound or droop. The arms have to transmit traction and braking loads, usually accomplished via a longitudinal link. They also have to control caster . Note that brake torques also have to be reacted - either by a second longitudinal link, or by rotating

135-424: A spindle to which the wheel bearings are mounted. To resist fore-aft loads such as acceleration and braking , the arms require 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

162-415: A time without affecting anything else. This is in direct contrast to a double wishbone suspension, where moving a hardpoint or changing a bushing compliance will affect two or more parameters. The benefit of the triangulated and double-triangulated arrangement is that they do not need a Panhard rod . The benefits of this are increased articulation and potential ease of installation. Multilink suspension

189-599: Is a type of independent vehicle suspension having three or more control links per wheel. These arms do not have to be of equal length, and may be angled away from their "obvious" direction. It was first introduced in the late 1960s on the Mercedes-Benz C111 and later on their W201 and W124 series. Typically each arm has a spherical joint (ball joint) or rubber bushing at each end. Consequently, they react to loads along their own length, in tension and compression, but not in bending. Some multi-links do use

216-423: Is costly and complex. It is also difficult to tune the geometry without a full 3D computer aided design analysis. Compliance under load can have an important effect and must be checked using a multibody simulation software. Source: Double wishbone A double wishbone suspension is an independent suspension design for automobiles using two (occasionally parallel) wishbone -shaped arms to locate

243-540: Is no genetic relationship between MacPherson strut and double wishbone suspension. Double wishbones have traditionally been considered to have superior dynamic characteristics as well as load-handling capabilities and are therefore commonly found on sports cars and racing cars throughout automotive history . Examples of cars with double wishbone suspension include the Aston Martin DB7 , the Mazda MX-5 , and

270-618: The Packard One-Twenty from 1935,[1] and advertised it as a safety feature. During that time MacPherson strut was still in the area of aviation technology and was derived from aircraft landing mechanisms. Later on, in 1951, Ford Company decided to use the MacPherson strut on small production cars, the English Ford Consul and Ford Zephyr.[2] Thus, the double wishbone was applied early in automobile history and there

297-576: The second-generation Peugeot 308 . The EMP2 V2 is the second iteration of the EMP2 platform, which debuted in 2016. The V2 supports mild hybrid and plug-in hybrid powertrains. The EMP2 V3 is the third iteration of the EMP2 platform, which debuted with the second-generation DS 4 . The improved platform introduced 70 percent new components compared to the previous iteration. It supports mild hybrid , plug-in hybrid and battery electric powertrains. Multi-link suspension A multi-link suspension

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324-489: The unsprung mass , and also allows the designer to make the suspension more aerodynamic. A short long arms suspension ( 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. In the latter case, the suspension can be called a multi-link, or dual-ball joint suspension . The four-bar linkage mechanism formed by

351-485: The arms themselves can be A-shaped or L-shaped. A single wishbone or A-arm can also be used in various other suspension types, such as variations of the MacPherson strut . The upper arm is usually shorter to induce negative camber as the suspension jounces (rises), and often this arrangement is titled an "SLA" or "short, long arms" suspension. When the vehicle is in a turn, body roll results in positive camber gain on

378-431: The beginning of jounce travel and then reverses into positive camber gain at high jounce amounts. Double wishbone suspensions are more complex, impose more difficult packaging constraints, and are thus often more expensive than other systems like a MacPherson strut . Due to the increased number of components within the suspension setup, it takes much longer to service and is heavier than an equivalent MacPherson design. At

405-427: The effect of moving each joint, so the kinematics of the suspension can be tuned easily and wheel motion can be optimized. 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

432-501: The function of a wishbone as long as the shape of the other wishbone provides control of the upright. This arrangement has been successfully used in the Jaguar IRS . In elevation 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 bushing or ball-joint locations. The various bushings or ball joints do not have to be on horizontal axes, parallel to

459-416: The hub, which forces the lateral arms out of plane, so allowing them to react 'spin' forces, or by rigidly fixing the longitudinal link to the hub. Multi-link suspension allows the auto designer the ability to incorporate both good ride and good handling in the same vehicle. In its simplest form, the multi-link suspension is orthogonal—i.e., it is possible to alter one parameter in the suspension at

486-439: The lightly loaded inside wheel, while the heavily loaded outer wheel gains negative camber. Between the outboard end of the arms is a knuckle. The knuckle contains a kingpin for horizontal radial movement in older designs, and rubber or trunnion bushings for vertical hinged movement. In newer designs, a ball joint at each end allows for all movement. Attached to the knuckle at its center is a bearing hub, or in many older designs,

513-418: The rod must be joined to the bottom of the upright and angled upward). As the wheel rises, the push rod compresses the internal spring via a pivot or pivoting system. The opposite arrangement, a "pull rod", will pull on the rod during bump travel, and the rod must be attached to the top of the upright, angled downward. Locating the spring and damper inboard increases the total mass of the suspension, but reduces

540-670: The same assembly line. PSA started production of the EMP2 platform at the Vigo plant (in Spain), under the 2013 Citroën C4 Picasso which was previewed by the Technospace concept car, and the 2013 Peugeot 308 , which is produced in the Sochaux plant in France. The EMP2 V1 is the first iteration of the EMP2 platform, which debuted in 2013 with the second-generation Citroën C4 Picasso and

567-496: The second-generation Peugeot 308 and second-generation Peugeot 408 . The later iteration of the EMP2 has a degree of flexibility which allows four different track widths, five different wheelbase lengths, two different cockpit architectures, two rear axle architectures, several rear vehicle modules for various versions (short, long, five or seven-seater, single seats or rear bench, combustion engine or hybrid ), and up to six different rear vehicle assemblies, which can be produced on

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594-592: The third through eighth generation of the Honda Accord . Short long arms suspension, a type of double wishbone suspension, is very common on front suspensions for medium-to-large cars such as the Peugeot 407 , Citroën C5 , and the first two generations of the Mazda6/Atenza . The double wishbone suspension provides the engineer with more design choices than some other types do. It is fairly easy to work out

621-401: The tire and the upper ball joint sits above the tire. Short spindle SLAs tend to require stiffer bushings at the body, as the braking and cornering forces are higher. Also, they tend to have poorer kingpin geometry, due to the difficulty of packaging the upper ball joint and the brakes inside the wheel. Long spindle SLAs tend to have better kingpin geometry, but the proximity of the spindle to

648-533: The tire restricts fitting oversized tires or snow chains. The location of the upper balljoint may have styling implications in the design of the sheet metal above it. SLAs require some care when setting up their bump steer characteristic, as it is easy to end up with excessive, or curved, bump steer curves. The double wishbone suspension was introduced in the 1930s. French car maker Citroën began using it in their 1934 Rosalie and Traction Avant models. Packard Motor Car Company of Detroit, Michigan , used it on

675-416: The unequal arm lengths causes a change in the camber of the vehicle as it rolls, which helps to keep the contact patch square on the ground, increasing the ultimate cornering capacity of the vehicle. It also reduces the wear on the outer edge of the tire. SLAs can be classified as short spindle, in which the upper ball joint on the spindle is inside the wheel, or long spindle, in which the spindle tucks around

702-409: The vehicle center line. If they are set at an angle, then anti-dive and anti-squat geometry can be dialed in. In many racing cars, the springs and dampers are relocated inside the bodywork. The suspension uses a bellcrank to transfer the forces at the knuckle end of the suspension to the internal spring and damper. This is then known as a "push rod" if bump travel "pushes" on the rod (and subsequently

729-555: 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 ( mechanical abrasion ), and more. The double-wishbone suspension can also be referred to as " double A-arms ", though

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