Editing Leaf spring (section)

===Types===
[[File:Three-quarter-elliptic leaf spring.jpg|thumb|Three-quarter-elliptic leaf spring on a carriage.]]
There are a variety of leaf springs, usually employing the word "elliptical". "Elliptical" or "full elliptical" leaf springs, patented in 1804 by the British inventor [[Obadiah Elliott]], referred to two circular arcs linked at their tips. This was joined to the frame at the top centre of the upper arc, the bottom centre was joined to the "live" suspension components, such as a solid front axle. Additional suspension components, such as [[trailing arm]]s, would usually be needed for this design, but not for "semi-elliptical" leaf springs as used in the [[Hotchkiss drive]]. That employed the lower arc, hence its name. 

"Quarter-elliptic" springs often had the thickest part of the stack of leaves stuck into the rear end of the side pieces of a short ladder frame, with the free end attached to the differential, as in the [[Austin 7|Austin Seven]] of the 1920s. As an example of non-elliptic leaf springs, the [[Ford Model T]] had multiple leaf springs over its differential that were curved in the shape of a [[yoke]]. As a substitute for dampers ([[shock absorber]]s), some manufacturers laid non-metallic sheets in between the metal leaves, such as wood.

Elliot's invention revolutionized carriage design and construction, removing the need for a heavy perch and making transportation over rough roadways faster, easier, and less expensive.<ref>{{cite web|url=https://www.gutenberg.org/files/46216/46216-h/46216-h.htm#Page_119|title=Carriages and Coaches|page=205}}</ref>

<gallery mode="packed" heights="120" widths="200" caption="Examples of leaf springs">
File:Spring 3 (PSF).png|alt=Carriage with elliptic springs|{{visible anchor|Elliptic}}
File:Semi elliptic spring and mounting (Manual of Driving and Maintenance).jpg|alt=Vehicle suspension with semi-elliptic springs|{{visible anchor|Semi-elliptic}}{{anchor|Half-elliptic}}
File:Back axle suspension springs.jpg|alt=Car suspension with three-quarter elliptic springs|{{visible anchor|Three quarter-elliptic}}
File:Quarter elliptic spring mounting (Manual of Driving and Maintenance).jpg|alt=Vehicle suspension with quarter-elliptic springs|{{visible anchor|Quarter-elliptic}}
File:Transverse leaf spring (Manual of Driving and Maintenance).jpg|alt=Front suspension with transverse leaf spring|{{visible anchor|Transverse}}
</gallery>

[[File:テーパーリーフスプリング概略図.svg|thumb|Tapered or parabolic leaf spring diagram]]
A more modern implementation is the parabolic leaf spring. This design is characterized by fewer leaves whose thickness varies from centre to ends following a [[parabola|parabolic curve]]. The intention of this design is to reduce inter-leaf friction, and therefore there is only contact between the leaves at the ends and at the centre, where the axle is connected. Spacers prevent contact at other points. Aside from weight-saving, the main advantage of parabolic springs is their greater flexibility, which translates into improved [[ride quality]], which approaches that of coil springs; the trade-off is reduced load carrying capability. They are widely used on [[buses]] for improved comfort.

A further development by the British GKN company and by Chevrolet, with the Corvette, among others, is the move to composite plastic leaf springs. Nevertheless, due to the lack of inter-leaf friction and other internal dampening effects, this type of spring requires more powerful dampers/shock absorbers.

Typically when used in automobile suspension the leaf both supports an axle and locates/partially locates the axle. This can lead to handling issues (such as "axle tramp"), as the flexible nature of the spring makes precise control of the [[unsprung mass]] of the axle difficult. Some suspension designs use a [[Watts link]] (or a [[Panhard rod]]) and radius arms to locate the axle and do not have this drawback. Such designs can use softer springs, resulting in a better ride. Examples include the various rear suspensions of [[Austin-Healey]] 3000s and [[Fiat 128]]s.