Originally Posted by aman_s1ngh
basically im doing an assignment on the development of cars from the benz velo (1884) car to the car in 1970's... what im trying to find at the moment is the advantages and disadvantages of the leaf spring suspension system...
Well, here's some info I've gathered....
Excluding the Corvette I'm aware of 4 general types of leaf spring suspensions.
1. Model T style transverse leaf.
This picture shows the transverse leaf used on a Ford Model-T. The suspension has two lateral arms that keep the front axle perpendicular with the chassis. Lateral axle movement is controlled by the spring. This system suffers from poor control of the axleís movements among other flaws. Iím not aware of any production car that uses this suspension type. Basically, this was held over from the horse drawn buggy days.
2. Conventional truck type, longitudinal leaf springs:
This is the one we all love to hate. Itís also about the only type of leaf spring suspension still in use other than teh totally unrelated modern Corvette setup. Itís cheep, durable and handles badly. It suffers from friction between the leaves and from poor control of the axleís location.
3. Golf cart style transverse leaf spring:
I couldnít find any pictures of this but it basically looks like a double A-arm where the leaf spring is one of the A-arms. The geometry is probably OK under vertical loads but lateral loads would defect the spring and cause camber changes. Not an issue for golf carts but bad for sports cars.
4. Leaf with links. There are lots of variations on this suspension
Miller Indy Roadster
Jaguar MkII rear suspension (canít find a picture)
Like #3, these suspensions uses a combination of links and the leaf spring to support the axle. The Jaguar set up looks similar to a 4 bar solid axle rear suspension except the lower link is the end of an inverted leaf spring. The other end for the leaf is attached to the chassis under the passenger compartment. The middle of the upside down (frown rather than smile) spring presses against a rubber block. The end connects to the bottom of the axle. This system offers better handling and axle control than #2 but is still suffers from friction between the leaves of the springs and compared to multi-link live axles, poor control of the axleís location.
What makes these all the same?
All of the above have several things in common. First, multi-leaf springs that suffer from friction between the leaves as the leaf flexes. Second, the inherently flexible leaf spring is being asked to work as a spring AND a suspension arm. Springs (leaf, coil, torsion etc) are good at being springs. They are bad at being other things like rigid links. In those suspension designs the spring is being asked to hold the axle and be a spring. To itís credit, the leaf spring does this much better than a coil spring. How well would a coil spring do that job? Think of a bobble head doll. In fact, cars like teh Renault 4CV used their rear coil springs as locators for the rear swing axle, which let them pivot all over, making for not only interesting camber changes, but bizzare toe changes as well.
Just to complete the leaf spring picture, the Corvette's suspension changed after the period your report is about, and the composite monoleaf setup is extremely high tech, and vastly different than any of the buggy spring setups described above. First, the Vette actually has double A-arm suspension like many other high end sports cars. The A-arms are used to fully control the movement of the wheels. The only difference between the Vette and other cars with A-arms is the Vette uses a leaf to pull the lower arm down rather than a coil spring to push it down. In both cases the spring is doing what it does best, being a spring ONLY.
The other problem was friction between the leaves of a leaf spring. Well, the Vette uses a single piece leaf so there is no internal friction, just like a coil spring.
So what we have is double A-arm geometry just using a different type of spring.