Springs and Fasteners

Fasteners

any device used to connect or join two or more components

rivet

a non-threaded fastener

Threaded fasteners

referred to by many names, among them bolts, screws, nuts, studs, lag screws, and set screws.

Major Diameter

Identify 1

Pitch Diameter

Identify 2

Minor diameter

Identify 3

Pitch

Identify 4

45 degree chamfer

Identify 5

Thread angle

Identify 6

Crest

Identify 7

Root

Identify 8

Threads

are the helical-cut area along the longitudinal length of bolt/screw.

Unified National Coarse

UNC

Unified National Fine

UFC

Grade

defines the strength of bolts and screws, which may be according to tensile strength, yield strength, and proof strength. Can be seen on head markings.

Proof strength

defines the stress at which the bolt or screw would be in permanent deformation

SAE

use numbers from 1 - 8

ASTM

use alphanumeric coding (i.e. A307, A325, etc)

Metric

bolts and screws use numeric coding from 4.6 to 12.9.

spring

is a flexible element used to exert a force or a torque and, at the same time, to store energy.

push

Helical compression spring,

Belleville spring

Torsion spring: force acting at the end of the torque arm Flat spring, such as a cantilever or leaf spring

pull

Helical extension spring

Torsion spring: force acting at the end of the torque arm

Flat spring, such as a cantilever or leaf spring

Drawbar spring (special case of the compression spring)

Constant-force spring

Radial Torque

Garter spring

elastomeric band

spring clamp

Torsion spring

power spring

Helical compression springs

are typically made from round wire, wrapped into a straight, cylindrical form with a constant pitch between adjacent coils.

free length

Without an applied load, the spring’s length is called the ____?

solid length

When a compression force 1s applied, the coils are pressed more closely together until they all touch, at which time the length is the minimum possible called the ______.

Helical extension springs

appear to be similar to compression springs, having a series of coils wrapped into a cylindrical form.

drawbar spring

incorporates a standard helical compression spring with two looped wire devices inserted through the inside of the spring.

With such a design, a tensile force can be exerted by pulling on the loops while still placing the spring in compression.

torsion string

A _____ is used to exert a torque as the spring is deflected by rotation about its axis.

spring-action clothespin

The common _____ uses a torsion spring to provide the gripping action.

Leaf springs

are made from one or more flat strips of brass, bronze, steel, or other materials loaded as cantilevers or simple beams.

Large forces

can be exerted within a small space by leaf springs.

Belleville spring

A _____ has the shape of a shallow, conical disk with a central hole.

Belleville washer

It is sometimes called a ________ because its appearance is simular to that of a flat washer.

small axial space

A very high spring rate or spring force can be developed in a ______ with such springs.

Garter springs

______ are coiled wire formed into a continuous ring shape so that they exert a radial force around the periphery of the object to which they are applied.

Constant-force springs

_______ take the form ofa coiled strip.

helical compression spring

In the most common form of ________ , round wire 1s wrapped into a cylindrical form with a constant pitch between adjacent coils.

operating length

The shortest length for the spring during normal operation is the _______

shortest length

When the valve is open, the spring assumes its _________

installed length

Then, when the valve is closed, the spring gets longer but still exerts a force to keep the valve securely on its seat. ~* The length at this condition is called the ________?

spring rate

The relationship between the force exerted by a spring and its deflection 1s called its ___

spring index

The ratio of the mean diameter of the spring to the wire diameter is called the _____?

5 to 12

typical machinery springs having C values ranging from ____?

Pitch

refers to the axial distance for a point on one coil to the corresponding point on the next adjacent coil.

12 degrees

Most practical spring designs produce a pitch angle less than about

coil clearance

The term ________ refers to the space between adjacent coils when the spring is compressed to its operating length, L,.

twisted

As a compressive spring is compressed under an axial load, the wire is _____?

buckle

The tendency for a spring to ______ increases as the spring becomes tall and slender, much as for a column.