Dependent suspensions

From
Technique: Dependent suspensions
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ReusabilityReversible
Designers: Phil Jergenson
Tools: Wrenches
Parts: Frames, Bolts, Nuts, End caps
Techniques: Bolting, Clevis fasteners, Tri joints, Live hinges

Introduction

Dependent suspensions may be differentiated by the system of linkages used to locate them, both longitudinally and transversely. Often, both functions are combined in a set of linkages.

Challenges

In a front-engine rear-drive vehicle, dependent rear suspension is either "live-axle" or deDion axle, depending on whether or not differential is carried on the axle. Live-axle is simpler, but unsprung weight contributes to wheel bounce.

Because it assures constant camber, dependent (and semi-independent) suspension is most common on vehicles that need to carry large loads as a proportion of the vehicle's weight, that have relatively soft springs and that do not (for cost and simplicity reasons) use active suspensions. The use of dependent front suspension has become limited to heavier commercial vehicles.

Approaches

  • Satchell link
  • Panhard rod
  • Watt's linkage
  • WOBLink
  • Mumford linkage
  • Leaf springs used for location (transverse or longitudinal)
    • Fully elliptical springs usually need supplementary location links, and are no longer in common use
    • Longitudinal semi-elliptical springs used to be common, and are still used in heavy-duty trucks and aircraft. They have the advantage, that the spring rate can easily be made progressive (non-linear).
    • A single transverse leaf spring for both front wheels and/or both back wheels, supporting solid axles, was used by Ford Motor Company, before and soon after World War II, even on expensive models. It had the advantages of simplicity and low unsprung weight (compared to other solid-axle designs).

References