A multi-link suspension is a type of vehicle suspension design typically used
in independent suspensions, using three or more lateral arms, and one or more
longitudinal arms. A wider definition considers 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 Mercedes-Benz
C111. and later on their W201 and W124 series,.
Typically each arm has a spherical 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 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. Solid axle configuration
For a solid axle vehicle the multi link suspension provides control of the axle
during suspension cycling and to locate the axle under the vehicle. The most
common is the four link with panhard bar. This is found in many cars and
pickup trucks. The four link is also used heavily in off-road racing and drag
racing. The four link for a solid axle has a few variations such as the
triangulated four link and double triangulated four link. Although common
in off-road vehicles these are not commonly found on the street.
Plan view The arms have to control toe/steer and
lateral compliance. This needs a pair of arms longitudinally separated.
Front view Independent Suspension
The arms have to control camber, particularly the way that the camber
changes as the wheel moves up and down into rebound or droop.
Solid Axle Suspension In a solid axle suspension the upper
arms may have an angle of at least 45 degrees between them, to prevent the
axle from moving from side to side while allowing the axle to articulate and move
freely up and down. Side view
Independent Suspension The arms have to react 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 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
For a solid axle the lower arms control forward and backward motion, the upper
arms control forward and backward rotation. This rotation is present under
acceleration and braking. Advantages of multi-link suspension
Benefit of independent suspension 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, 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.
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 desert racing.
In desert racing, the use of a good sway bar is needed to counter body roll.
Benefits of solid-axle multi-link suspension
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. The 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 of multi-link suspension Multilink suspension 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.
Gallery See also
Suspension Automotive suspension design
Mercedes-Benz C111 References
Adams, H.. Chassis Engineering New York, New York, Penguin Putnam
Milliken, W.F., Milliken, D. Chassis Design: Principles and Dynamics, SAE
International External links
AutoZine Technical School site "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