of Spring Terminology
which are free to deflect under load.
relationship of ends
position of the plane of the hooks or loops of extension springs to each
electroplated springs to relieve hydrogen embrittlement.
lateral deflection of compression springs when com pressed, related to the
slenderness ratio (L/D).
compression springs where pitch of the end coils is reduced so that the
end coils touch.
closed ends, except that the end is ground to provide a flat plane.
adjacent coils touching.
spring ends or arms under the application or removal of an external load
stress to which a material may be subjected without permanent set.
stress at which any given material will operate indefinitely without
failure for a given minimum stress.
the arms of a torsion spring when the spring is not loaded.
length of a spring in the unloaded position.
inherent rate of free vibration of a spring itself (usually in cycles per
second) with ends restrained.
See Rate (R).
spring at elevated temperature to minimize loss of load at operating
form (open or closed) of compression, extension, and torsion springs.
proportional to displacement.
Open loops or
ends of extension springs.
absorbed in electroplating or pickling of carbon steels, tending to make
the spring material brittle and susceptible to cracking and failure,
particularly under sustained loads.
mechanical energy loss that always occurs under cyclic loading and
unloading of a spring, proportional to the area between the loading and
unloading load-deflection curves within the elastic range of a spring.
that tends to keep the coils of an extension spring closed and which must
be overcome before the coils start to open.
force applied to a spring that causes a deflection (F).
wire shapes at the ends of extension springs that provide for attachment
and force application.
spring diameter (O.D.) minus one wire diameter (d).
shear or torsion (G)
of stiffness for extension and compression springs.
tension or bending (E)
of stiffness used for torsion and flat springs (Young's Modulus).
End of a
compression spring with a constant pitch for each coil.
ends, not ground" followed by an end grinding operation.
treatment of stainless steel to remove contaminants and improve corrosion
that is deflected so far that its elastic properties have been exceeded
and it does not return to its original condition upon release of load is
said to have taken a "permanent set."
from center to center of the wire in adjacent active coils (recommended
practice is to specify number of active coils rather than pitch).
ratio of the strain in the transverse direction to the strain in the
load per unit deflection, generally given in pounds per inch. (N/mm)
of closing to solid height a compression spring which has been coiled
longer than the desired finished length, so as to increase the apparent
induced by set removal, shot peening, cold working, forming or other means.
These stresses may or may not be beneficial, depending on the application.
distortion which occurs when a spring is stressed beyond the elastic limit
of the material.
process in which the material surface is peened to induce compressive
stresses and thereby improve fatigue life.
spring length (L) to mean coil diameter (D).
Length of a
compression spring when under sufficient load to bring all coils into
contact with adjacent coils.
Ratio of mean
coil diameter (D) to wire diameter (d).
and ground ends.
deviation between the axis of a compression spring and a line normal to
the plane of the ends.
Squareness of ends, except with the spring under load.
difference in operating stresses at minimum and maximum loads.
springs to low-temperature heat treatment so as to relieve residual
action in torsion springs which tends to produce rotation, equal to the
load multiplied by the distance (or moment arm) from the load to the axis
of the spring body. Usually expressed in oz./in., lb./in., lb./ft., or in.
number of coils (Nt)
active coils (Na) plus the coils forming the ends.
A factor to
correct stress in helical springs effects of curvature and direct shear.