Glossary
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.
Term | Definition |
---|---|
Active Coils | Those coils which are free to deflect under load. * |
Angular Relationship of Ends | Relative position of hooks or loops of an extension spring (ends of a torsion spring) to each other. * |
Baking | Heating of electroplated springs to relieve hydrogen embrittlement. * |
Buckling | Bowing or lateral displacement of a compression spring. Related to slenderness ratio. * |
Close Ends | Compression spring ends with coil pitch angle reduced so they are square with the spring axis and touch the adjacent coils. * |
Closed and Ground Ends | Closed End spring in which the first and last coil are ground to provide a flat bearing surface. * |
Close Wound | Adjacent coils are touching. * |
Deflection | Motion imparted to a spring by application or removal of an external load. * |
Elastic Limit | Maximum stress to which a material may be subjected without permanent set. * |
Endurance Limit | Maximum stress, at a given stress ratio, at which material will operate in a given environment for a stated number of cycles without failure. * |
Fixture Tempering | Restraining parts during tempering to improve dimensional control. * |
Free Angle | Angular relationship between arms of a helical torsion spring which is not under load. * |
Free Length | Overall length of a spring which is not under load. * |
Heat Setting | A process to pre-relax a spring in order to improve stress relaxation resistance in service. * |
Helical Springs | Springs made of bar stock or wire coiled into a helical form. This category includes compression, extension and torsion springs. * |
Hooks | Open loops or ends of extension springs. * |
Hysteresis | Mechanical energy loss occurring during loading and unloading of a spring within the elastic range, illustrated by the area between load deflection curves. * |
Initial Tension | 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. * |
Loops | Formed ends with minimal gaps at the ends of extension springs. * |
Mean Diameter | 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. * |
Modules in Tension or Bending | (Young’s Modulus E) – Coefficient of stiffness used for torsion or flat springs. * |
Modules in Shear or Torsion | (Modulus of Rigidity G) – Coefficient of stiffness used for compression and extension springs. * |
NASCAR | Abbreviation for the National Association for Stock Car Auto Racing. www.nascar.com |
Natural Frequency | Lowest inherent rate of free vibration of a spring vibrating between its own ends. * |
Patenting | Process of heating carbon steel above its critical temperature and cooling at a controlled rate to achieve a fine, pearlitic microstructure. * |
Pitch | The distance from center to center of wire in adjacent coils of an open wound spring. Also known as Coils per Inch. * |
Plain Ends | End coils of a helical spring having a constant pitch. Ends not squared. * |
Plain Ends, Ground | End coils of a helical spring having a constant pitch and wire ends ground square with the axis. * |
Rate | Spring gradient, or change in the load per unit of deflection. * |
Rear-End Locker Springs | Also known as Differential Locker Springs. |
Residual Stress | Stress mechanically induced by such means as set removal, shot peening, cold working or forming. Benefits depend on the spring application. * |
Set | Permanent change of length, heigh or position after a spring is stressed beyond the material’s elastic limit. * |
Set Percentage | Amount of set divided by the deflection which produced it. * |
Set Point | Stress at which some arbitrarily chosen amount of set (usually 2%) occurs. * |
Set Removal | An operation which causes a permanent loss of length or heigh due to spring deflection. * |
Shot Peening | Blasting the surfaces of spring material with steel or glass pellets to induce compressive stresses that improve fatigue life. * |
Slenderness Ratio | Ratio of spring length to mean diameter (L/D) in helical springs. * |
Solid Height | 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. * |
Spiral Springs | 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. * |
Spring Index | Ratio of mean diameter to wire diameter. * |
Squareness | Angular deviation between the axis of a compression spring in a free state and a line normal to the end planes. * |
Stress Range | Difference in operating stresses at minimum and maximum loads. * |
Stress Ratio | Minimum stress divided by maximum stress * |
Stress Relief | A low temperature heat treatment given springs to relieve residual stresses produced by prior cold forming. * |
Torque | 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. * |
Total Number of Coils | 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.
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