A multi-link suspension is a type of independent

vehicle suspension Suspension is the system of tires, tire air, spring (device), springs, shock absorbers and Linkage (mechanical), linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support b ...

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 The Mercedes-Benz W124 is a range of executive 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 s ...

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, 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.

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

toe Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being ''digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being ''plantigrade''; ...

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

Advantages

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 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 A Panhard rod (also called Panhard bar, track bar, or track rod) is a suspension link that provides lateral location of the axle. Invented by the Panhard automobile company of France in the early twentieth century, this device has been widely use ...

. The benefits of this are increased articulation and potential ease of installation.

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 c ...

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

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