Explanation of Terms - Extension Springs
Matl. Spec. - The type of spring wire used.
Dir. of Coil (R/L) - Coil direction can be either right-hand or left-hand.
Wire Diam. (d) - The size of spring wire used.
Coil O.D. - The outside diameter of the coil.
Coil M.D. - The mean (average) of the outside and inside diameters.
Coil I.D. - The inside diameter of the coil.
Spring Index (D/d) - The ratio of coil M.D. to wire diameter. For ease of manufacturing, this value should stay between 5 and 10 if possible.
Length Overall - The overall length of the spring.
Inside Hooks - The length inside the hooks of the spring.
Length Over Body - The length of the coiled portion of the spring.
Ideal Inside Hook Length - The ideal length inside the hooks. The value can vary somewhat from the required length inside hooks. The bigger the variation, the harder it is to make the hooks.
Initial Tension - An initial force wound into the spring that keeps the coils together. There is a limit as to how much can be put into the spring depending on its physical dimensions.
Max Travel - The amount of extension that the spring can withstand without any permanent deformation. This value can be exceeded somewhat depending on the application of the spring. It is based on a spring life of one million cycles.
Active Coils - The number of coils affecting the load rate of the spring.
Total Coils - The number of active coils plus the hooks of the spring.
Spring Weight - The weight of the spring.
Load Rate - The amount of force exerted by the spring for every one inch of travel. It depends upon the wire diameter, coil M.D. and number of active coils.
Type of Ends (SM, SLC) - The type of hooks used on each end on the spring.
Pos of Ends (INL, RAN) - The position of the hooks in relation to one another.
Hook Opening - The space between the end of the hook and the beginning of the coils.
Finish - The type of finish to be applied to the spring; painted, etc.
