leaf springs were very common on automobiles, right up to the 1970s in europe and japan and late 1970s in america when the move to front-wheel drive, and more sophisticated suspension designs saw automobile manufacturers use coil springs instead. today leaf springs are still used in heavy commercial vehicles such as vans and trucks, suvs, and railway carriages. for heavy vehicles, they have the advantage of spreading the load more widely over the vehicle's chassis, whereas coil springs transfer it to a single point. unlike coil springs, leaf springs also locate the rear axle, eliminating the need for trailing arms and a panhard rod, thereby saving cost and weight in a simple live axle rear suspension. a further advantage of a leaf spring over a helical spring is that the end of the leaf spring may be guided along a definite path.