Multi-link suspension
A multi-link suspension is a type of vehicle suspension with one or more transversal arms.[citation needed] 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 Mercedes-Benz C111[1] and later on their W201 and W124 series.[2][3]
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.
The solid axle 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[edit]
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/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. 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.
- Multi-link beam suspension
- This setup is used on front-wheel-drive vehicles, where the solid axle is modified with a Scott Russell linkage straight-line mechanism that uses two rods to create a link that moves straight up and down and requires that one of the attachment points be able to slide,[4] which is similar to a twist-beam rear suspension.
Advantages[edit]
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 adaptability of the multi-link suspension is a significant advantage, particularly in off-road driving. It allows the vehicle to flex more, meaning the suspension can easily adjust to the varying angles of off-road driving. This adaptability makes multi-link-equipped vehicles an ideal choice for sports such as desert racing. [citation needed] In desert racing, a reliable sway bar is crucial to counter body roll.
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.
When it comes to solid axle applications, the multi-link suspension offers a clear advantage over the independent multi-link. It is significantly more cost-effective and less complex to build, providing a practical solution without compromising on performance.
Disadvantages[edit]
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[edit]
Source:[5]
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5-link rear wheel suspension mechanism (front view) -
5-link rear wheel suspension mechanism (top view) -
5-link suspension mechanism with rack-and-pinion steering input (front view) -
5-link suspension mechanism with rack-and-pinion steering input (top view)
See also[edit]
References[edit]
- ^ Bastow, D. (1970) Suspension ad Steering, Automobile Engineer, 8 May 1970, 217–231.
- ^ von der Ohe, M. (1984) Independent Wheel Suspension, US Pat. 4,444,415, Filed Dec. 23, 1981
- ^ von der Ohe, M. (1983) Front and Rear Suspension of the New Model W201, SAE technical Paper 831045.
- ^ US 6179328, Kawagoe, Kenji; Nakajima, Hikaru & Suetsugu, Yukihiro, "Vehicle rear suspension apparatus", published 2001-01-30, assigned to Nissan Motor Co. Ltd.
- ^ Simionescu, P.A. (2014). Computer Aided Graphing and Simulation Tools for AutoCAD Users (1st ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4822-5290-3.
- 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[edit]
- "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
