A multi-link suspension is a type of

vehicle suspension 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 ...

with one or more longitudinal arms. A wider definition can consider any independent suspensions having three control links or more multi-link suspensions. 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

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and later on their W201 and

W124 The Mercedes-Benz W124 is a range of mid-size cars made by Daimler-Benz from 1984 to 1997. The range included numerous body configurations, and though collectively referred to as the W-124, official internal chassis designations varied by body st ...

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 a

trailing arm A (semi) trailing-arm suspension, sometimes referred to as (semi) trailing-link is a vehicle axle or wheel suspension design in which one or more horizontal arms (or "links"), perpendicular to and forward of the axle, are connecting the axle or ...

control arm In automotive suspension, a control arm, also known as an A-arm, is a hinged suspension link between the chassis and the suspension upright or hub that carries the wheel. In simple terms, it governs a wheel's vertical travel, allowing it to mo ...

wishbone Wishbone commonly refers to: * Furcula, a fork-shaped bone in birds and some dinosaurs Wishbone may also refer to: * Wish-Bone, an American salad dressing and condiment company * Wishbone formation, a type of offense in American football * Wish ...

, which has two bushings at one end. On a front suspension one of the lateral arms is replaced by the

tie-rod A tie rod or tie bar (also known as a hanger rod if vertical) is a slender structural unit used as a tie and (in most applications) capable of carrying tensile loads only. It is any rod or bar-shaped structural member designed to prevent the separa ...

, which connects the rack or steering box to the wheel hub. The

solid axle Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ri ...

multi-link system is another variation of the same concept, and offers some advantages over independent multi-link, as it is significantly cheaper and less complex to build, offering good mechanical resistance and excellent reliability with very similar benefits.

Layout

In order to simplify understanding, it is usual to consider the function of the arms in each of three orthogonal planes: *Top view: The arms have to control

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/steer and lateral compliance. This needs a pair of arms longitudinally separated. *Front view: The arms have to control

camber Camber may refer to a variety of curvatures and angles: * Camber angle, the angle made by the wheels of a vehicle * Camber beam, an upward curvature of a joist to compensate for load deflection due in buildings * Camber thrust in bike technology * ...

, particularly the way that the camber changes as the wheel moves up (into jounce, or bump) and down into rebound or droop. *Side view: The arms have to transmit traction and braking loads, usually accomplished via a longitudinal link. They also have to control

caster A caster (or castor) is an undriven wheel that is designed to be attached to the bottom of a larger object (the "vehicle") to enable that object to be moved. Casters are used in numerous applications, including shopping carts, office chairs, t ...

. Note that brake torques also have to be reacted - either by a second longitudinal link, or by rotating 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. ;Solid axle suspension:When used in a solid axle suspension the multi-link system use the lower arms to control forward and backward motion, and the upper arms to control forward and backward rotation. This rotation is present under acceleration and braking. Axle - 5 Link rigid 03

Advantages

Multi-link suspension allows the auto designer the ability to incorporate both good

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and good handling in the same vehicle. In its simplest form, multi-link suspension is orthogonal—i.e., it is possible to alter one parameter in the suspension at a time, without affecting anything else. This is in direct contrast to a

double wishbone A double wishbone suspension is an independent suspension design for automobiles using two (occasionally 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 ...

suspension, where moving a hardpoint or changing a bushing compliance will affect two or more parameters. Advantages also extend to off-road driving. A multi-link suspension allows the vehicle to flex more; this means simply that the suspension is able to move more easily to conform to the varying angles of off-road driving. Multi-link-equipped vehicles are ideally suited for sports such as

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. In desert racing, the use of a good

sway bar An anti-roll bar (roll bar, anti-sway bar, sway bar, stabilizer bar) is a part of many automobile suspension (vehicle), suspensions that helps reduce the body roll of a vehicle during fast cornering or over road irregularities. It connects opposi ...

is needed to counter body roll. The benefit of the triangulated and double-triangulated arrangement is that they do not need a panhard bar. The benefits of this are increased articulation and potential ease of installation. Multi-link for solid axle offers a benefit over the independent multi-link in that it is significantly cheaper and much less complex to build.

Disadvantages

Multilink suspension is costly and complex. It is also difficult to tune the geometry without a full 3D

computer aided design Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve co ...

analysis. Compliance under load can have an important effect and must be checked using a

multibody Multibody system is the study of the dynamic behavior of interconnected rigid or flexible bodies, each of which may undergo large translational and rotational displacements. Introduction The systematic treatment of the dynamic behavior of inte ...

simulation software.

Gallery

Source: File:5link-rear1-small.gif, 5-link rear wheel suspension mechanism (front view) File:5link-rear2-small.gif, 5-link rear wheel suspension mechanism (top view) File:5link-steer front view.gif, 5-link suspension mechanism with rack-and-pinion steering input (front view) File:5link-steer top view.gif, 5-link suspension mechanism with rack-and-pinion steering input (top view)

References

*Adams, H. (1993). ''Chassis Engineering''. New York, New York, Penguin Putnam. *Milliken, W.F., Milliken, D. (2002). ''Chassis Design: Principles and Dynamics'', SAE International.

External links

"What is: Multilink suspension?" from CarPoint Australia

1998 technical paper on the design of multilink suspensions

2002 technical paper on the design and analysis of five-link suspensions
{{Use dmy dates, date=March 2018 Automotive suspension technologies