What is the free length of a spring?
For a compression spring this is measured from one end of the spring to the other when no load is applied. For an extension spring this is measured from inside diameter of each hook before any load is applied. • What is solid height (for a compression spring)? The solid height is the measurement of the spring when it is completely compressed. At this point all the coils are now touching and there is no more space for the spring to compress further. Depending on the spring design and the requirements of the spring, not all springs can safely be compressed to solid. If the spring is overstressed at solid, the spring will begin to take a set. When this spring is returned to its uncompressed state it will be shorter than the it was originally. It is important to make sure the design of each spring allows it to be compressed to the desired height safely, and without added stress, to ensure proper life of the spring. • What is initial tension (extension spring)? Extensions springs require a
