A suspension system is a system of springs, shock absorbers and linkages, they connect a vehicle to its wheels and allow relative motion between them both. They’re responsible for a vehicle’s handling and braking for safety, there’s a variety of independent suspension systems, but we’ll be comparing The Leaf Spring System and the Coil Spring System.
If a leaf spring suspension is made of a series of relatively long strips of steel and is attached at both ends to a frame and suspends the axle in the middle. A leaf spring will take the form of a slender arc-shaped length of spring steel of a rectangular cross-section. Coil springs look exactly like a spring, they sit on top of the axle or at the lower control arm and chassis. A coil by definition is a mechanical device which is typically used to store energy and subsequently release it, to absorb shock or to maintain a force between contacting surfaces.
Leaf spring suspensions are simpler when it comes to the functionality as the axle is suspended by the spring and doesn’t require arduous suspension geometry of the coil-spring set-up. Leaf springs are much sturdier in comparison to coil springs. They’re capable of handling much highest loads with less deflection than coils, trucks with leaf springs are also easier to raise or lower.
Leaf springs’ simplicity means each spring is attached at fixed points on the chassis, it leaves a miniscule area for adjustability and customisation of the suspension geometry. These springs also flex a great deal less than coil springs which means loss of wheel-to-ground contact under extreme conditions.
Coil spring suspensions provide more range of suspension movement and allow the user a wider turning envelop through the suspension range than the leaf springs. Practically all high performance applications use coil springs where possible if the budget permits.
Two main drawbacks to a coil spring suspension are the cost and load-bearing, cost isn’t much of an issue if the vehicle is equipped with coil springs, retro-fits are quite expensive and time consuming. Coils are not ordinarily preferred for heavy vehicles as the coil on axle setup isn’t remotely as stable or strong as proper leaf springs.
Each of these suspension systems have their applications unique to their functionality and are used accordingly. Leaf springs usually do an acceptable job and prove themselves a durable choice in the case of heavy, industrial or budget-limited applications. There are a very few applications which benefit from choosing a leaf spring over a coil spring when it comes to performance.