When leaf springs are installed in a vehicle's suspension, the vertical load they bear causes each spring leaf to deform, tending to arch upwards. At this point, the axle and frame move closer to each other. When the axle and frame separate, the positive vertical load and deformation on the leaf springs gradually decrease, and sometimes even reverse.
To improve the stress distribution on the main leaf's eye, the end of the second leaf is often bent into an eye and wrapped around the outside of the main leaf's eye; this is known as a wrapped eye. At the same time, a larger gap needs to be left between the main leaf's eye and the second leaf's wrapped eye to allow the leaves to slide relative to each other during elastic deformation. Furthermore, some leaf springs in suspensions do not use an eye shape at both ends but instead employ other support connection methods, such as rubber support pads. Additionally, flat rectangular leaf springs are usually stacked in multiple layers. One end is installed on a hanger with a shackle, and the other end is connected to the chassis frame using a shackle, allowing the spring to expand and contract. These springs are currently widely used in some body-on-frame off-road vehicles and commercial vans/trucks.
