Suspension Spring & Component Glossary

Abbreviations, acronyms, buzzwords, and engineering tech-speak exist in every industry. Hyperco defines several racing and spring-related terms and phrases you might come across as you peruse our site.

Those coils which are free to deflect under load. *

Relative position of hooks or loops of an extension spring (ends of a torsion spring) to each other. *

Heating of electroplated springs to relieve hydrogen embrittlement. *

Bowing or lateral displacement of a compression spring. Related to slenderness ratio. *

Compression spring ends with coil pitch angle reduced so they are square with the spring axis and touch the adjacent coils. *

Closed End spring in which the first and last coil are ground to provide a flat bearing surface. *

Adjacent coils are touching. *

Motion imparted to a spring by application or removal of an external load. *

Maximum stress to which a material may be subjected without permanent set. *

Maximum stress, at a given stress ratio, at which material will operate in a given environment for a stated number of cycles without failure. *

Restraining parts during tempering to improve dimensional control. *

Angular relationship between arms of a helical torsion spring which is not under load. *

Overall length of a spring which is not under load. *

A process to pre-relax a spring in order to improve stress relaxation resistance in service. *

Springs made of bar stock or wire coiled into a helical form. This category includes compression, extension and torsion springs. *

Open loops or ends of extension springs. *

Mechanical energy loss occurring during loading and unloading of a spring within the elastic range, illustrated by the area between load deflection curves. *

A force that tends to keep coils of a close wound extension spring closed and which must be overcome before the coils start to open. *

Formed ends with minimal gaps at the ends of extension springs. *

The average diameter of the mass of spring material, equal to one half the sum of the outside and inside diameters. In a helical spring, this is equivalent to the outside diameter minus one wire diameter. *

(Young’s Modulus E) – Coefficient of stiffness used for torsion or flat springs. *

(Modulus of Rigidity G) – Coefficient of stiffness used for compression and extension springs. *

Abbreviation for the National Association for Stock Car Auto Racing.

Lowest inherent rate of free vibration of a spring vibrating between its own ends. *

Process of heating carbon steel above its critical temperature and cooling at a controlled rate to achieve a fine, pearlitic microstructure. *

The distance from center to center of wire in adjacent coils of an open wound spring. Also known as Coils per Inch. *

End coils of a helical spring having a constant pitch. Ends not squared. *

End coils of a helical spring having a constant pitch and wire ends ground square with the axis. *

Spring gradient, or change in the load per unit of deflection. *

Also known as Differential Locker Springs.

Stress mechanically induced by such means as set removal, shot peening, cold working or forming. Benefits depend on the spring application. *

Permanent change of length, heigh or position after a spring is stressed beyond the material’s elastic limit. *

Amount of set divided by the deflection which produced it. *

Stress at which some arbitrarily chosen amount of set (usually 2%) occurs. *

An operation which causes a permanent loss of length or heigh due to spring deflection. *

Blasting the surfaces of spring material with steel or glass pellets to induce compressive stresses that improve fatigue life. *

Ratio of spring length to mean diameter (L/D) in helical springs. *

Length of a compression spring when deflected under sufficient load to bring all adjacent coils into contact, with no additional deflection possible. Also known as Block or Closed Height. *

Springs formed from flat strip or wire wound in the form of a spiral, loaded by torque about an axis normal to the plane of the spiral. *

Ratio of mean diameter to wire diameter. *

Angular deviation between the axis of a compression spring in a free state and a line normal to the end planes. *

Difference in operating stresses at minimum and maximum loads. *

Minimum stress divided by maximum stress *

A low temperature heat treatment given springs to relieve residual stresses produced by prior cold forming. *

A product of the distance from the spring axis to the point of load application, and the force component normal to the distance line. Also known as Moment. *

The sum of the number of active and inactive coils in a spring body. *

*- © 2000, Spring Manufacturers Institute. All Rights Reserved.
Used with the express written permission of the Spring Manufacturers Institute.