Back to basics on gas strut types and options
Gas struts come in many shapes and sizes, and various types. We asked the experts at Alrose to explain what’s available, and what makes them different and thus suitable for different tasks.
Gas struts, often referred to as gas springs, are essential components in a host of applications. Compression gas struts provide an outwards pushing force that can be utilised to assist the movement of an object, ie helping in the movement of a door or hatch The basic configuration includes a rod with piston attached that moves up and down inside a gas/oil chamber. As the rod moves into the body of the gas strut it reduces the volume that the gas/oil can occupy and thus the pressure inside the sealed tube increases and an outwards force is exerted on the rod.
Under the umbrella of compression gas struts, there is a whole range of options, including standard compression gas struts, side valve versions, locking versions, friction lock versions, lock open versions and protected compression gas struts.
The standard compression gas struts have the rod out and the load from the application forces the rod in. Typically a gas strut is mounted so they are rod down in the position in which they spend the most time. This allows the oil contained within the gas strut to lubricate the rod seals.
The side valve compression gas strut has the same basic concepts as a compression gas strut but this product has a side release valve that is operated with an Allen key. You can release the pressure whilst the gas spring is on the application, saving you time.
With a locking gas strut, the product provides a pushing force like a compression gas spring but can be locked off in any position by the simple action of a lever or remote button. The force required to activate or deactivate the lock is called the release force, and is a factor of the ratio of the piston rod area to the valve area, 4:1. Theoretically, then, is a quarter of the extension force of the piston rod, but in practice you must take into account the force required to break loose the seals on actuation, so increasing the releasing force.
Friction lock compression gas struts use a large, easy to grip nut to quickly lock off the gas strut in any position you wish. The spring operates just like a standard compression gas strut when unlocked.
Lock open compression gas struts consist of a standard compression gas strut with a special protection sleeve which is on a pivot mounting. This sleeve automatically falls into place when the gas strut has reached its full extension, effectively locking your application in the open position. Providing a safety locking function, this is ideal if you have, for example, a heavy hatch or lid that may be exposed to wind loading or other intermittent force.
If your application is in a dusty or dirty environment, likely to suffer impacts to the rod or of a particularly long stroke length, then it is advisable to use protected compression gas strut. Here, an anti-buckle sleeve overlaps the body of the gas spring, fitting snugly over it. As you move the spring from an open to closed position the sleeve stays around the body helping prevent ingress of dust and dirt onto the rod and then the seals, something that could potentially cause your spring to fail. It also serves to strengthen the spring against side loading and potential buckling.
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