A gas spring is a type of
spring
Spring(s) may refer to:
Common uses
* Spring (season)
Spring, also known as springtime, is one of the four temperate seasons, succeeding winter and preceding summer. There are various technical definitions of spring, but local usage of ...
that, unlike a typical mechanical spring that relies on
elastic deformation
In engineering, deformation refers to the change in size or shape of an object. ''Displacements'' are the ''absolute'' change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain ...
, uses
compressed gas
A compressed fluid (also called a compressed or unsaturated liquid, subcooled fluid or liquid) is a fluid under mechanical or thermodynamic conditions that force it to be a liquid.
At a given pressure, a fluid is a compressed fluid if it is at ...
contained within an enclosed
cylinder
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an infin ...
sealed by a sliding
piston to
pneumatically store
potential energy and withstand external
force applied parallel to the direction of the piston shaft.
Common applications include automobiles (where they are incorporated into the design of
strut
A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension.
Human anatomy
Part of the functionality o ...
s that support the weight of the
hatchback tailgate while they are open) and office chairs. They are also used in furniture, medical and aerospace applications. Much larger gas springs are found in machines that are used in industrial manufacturing (the press tooling industry), where the forces they are required to exert often range from 2500N to 400,000N (forty tonnes).
Types
Gas springs are manufactured in many varieties including:
* Standard cylinder
* Fixed-height cylinder
* Spindle only
* Cable cylinder
* Stage cylinder
* Non-rotating cylinder
* Return cylinder (no height adjustment)
* Auto-return cylinder with height adjustment
* Bouncing cylinder
* Dual-mode cylinder
* Heavy duty cylinder
* Oil damper
Forms
If the internal plunger has a diaphragm which extends to the side of the gas tube, it will cease to move once an applied force is constant and will support a weight, like a normal spring. If a fine hole exists in the plunger, however, it is termed a "slow-dampened spring" and can be used on heavy doors and windows. A gas spring designed for fast operation is termed a "quick gas spring" and is used in the manufacture of
air guns and
recoil buffer A recoil buffer is a factory-installed or aftermarket component of firearms which serves to reduce the velocity and/or cushion the impact of recoiling parts of a firearm.
Design
The simplest form of recoil buffer is made from a resilient and deform ...
s.
Reducing the gas volume and hence increasing its internal pressure by means of a movable end stop, or allowing one tube to slide over another, can allow the characteristics of a gas spring to be adjusted during operation. The rod may be hollow by use of clever seals or may consist of multiple small-diameter rods. A small amount of oil is normally present.
The gas may be introduced by a
Schrader-type valve, using a
lip seal around the rod and forcing it to allow gas in by external overpressure or a shuttling
O-ring
An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...
system. Gas springs of high pressure contain a very large amount of energy and can be used as a power pack. In emergency use the gas may be introduced via a
gas generator cell, similar to those used in
airbags.
Passive heave compensators features large gas springs. The stroke lengths can exceed 6 meters.
Features
A variety of features are available from various manufacturers:
*Adjustable push-in force via a local knob or remote via a
bowden wire.
*Single touch release to allow full extension or the ability to lock it out.
*Extended stroke through telescoping mechanisms, usually composed of one rod and two cylinders (the smaller of the two cylinders actually acts as a second rod extending in and out of the larger cylinder).
* Vari-lift - intended for short production runs and prototypes, in applications where the exact force is important but hard to estimate in advance, such as lifting a lid slowly in a known time. In this case the cylinder is supplied filled to maximum design pressure, but equipped with a bleed port, to allow gas to be released once installed. The intention is that the design can be over-sprung, and then the pressure reduced in stages, to optimise behaviour. If too much gas is released, a new spring must be installed, and for large quantities, it is better to order a bespoke pressure setting from the maker.
*Degressive springs where the spring becomes more, not less, powerful as the main cylinder expands.
See also
*
Shock absorber
References
{{DEFAULTSORT:Gas Spring
Springs (mechanical)