Springs are of several types, the most plentiful of which are shown as follows,
Circular cross section springs are shown. If space is limited, such as with automotive valve springs, square cross section springs can be considered. If space is extremely limited and the load is high, Belleville washer springs can be considered. These springs are illustrated below,
Leaf springs, which are illustrated below in a typical wheeled-vehicle application, can be designed to have progressive spring rates. This "non-linear spring constant" is useful for vehicles which must operate with widely varying loads, such as trucks.