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A locking gas spring incorporates a mechanism to enable the rod to be locked at any point in its travel. This mechanism is actuated by a plunger that protrudes from the rod. When this plunger is depressed the rod is free to operate as normal. When the plunger is released, which may be at any point in the stroke, the rod is locked in that position. IGS offers three types of locking gas springs, which have the following characteristics when locked:

Flexible: Good resistance to rod being pushed or pulled
Rigid in Tension: Rigid when rod is being pulled, high resistance to rod being pushed
Rigid in Compression: High resistance to rod being pulled, rigid when rod is being pushed.

Click on the options to the right for additional information.

All three types of locking springs have the same locking mechanism. This locking mechanism operates when the plunger rod is depressed by opening a valve in the piston. When the plunger rod is released the valve closes and the passage of oil or gas is prevented, locking the piston in that position.

Release valve: Both flexible and rigid in tension gas springs can be supplied with a release valve, which allows the installer to reduce the force. This release valve also allows IGS to easily and economically recharge the gas spring should too much gas be released.

FLEXIBLE LOCKING GAS SPRINGS:
A flexible locking gas spring has gas on both sides of the piston. Gas is compressible so if sufficient force is applied to the rod when it is in its locked state, either in tension or compression, the gas will compress and the rod will move a few millimeters from its locked position. When the force is removed the rod will return to its original position, while remaining locked, giving the characteristic flexing movement.

A small quantity of oil is inserted into the spring so that in its normal rod down position, the seal is lubricated for maximum life. Other orientations are possible by the addition of an oil chamber.

RIGID IN TENSION GAS SPRINGS:
Rigid in tension locking gas springs have oil on both sides of the piston such that the chamber between (where the rod enters the body) and the piston is always full of oil. This oil is contained by a floating piston that separates it from the gas in the enclosed tube. Since oil is incompressible, when a tension load is applied to the locked rod the oil between the nose bearing and the piston will not compress and the rod cannot move.

When a locked, rigid in tension springs is subjected to a compression load, only the compressible gas resists the force transmitted from the piston to the floating piston. This gas will consequently compress and permit the rod to move. However, because the oil on the other side of the locked piston cannot expand the movement permitted is significantly less than experienced on a flexible locking gas spring. In addition, because the oil is always held between the piston and nose bearing (containing the main seal), a rigid in tension spring can be used in any orientation.

Applications for rigid in tension locking springs include hospital beds, aircraft, coach and rail seat back recline control and wheel chair recline and support systems.

RIGID IN COMPRESSION GAS SPRINGS:
These are similar to the rigid in tension locking springs with oil on both sides of the piston. However, in the case of a rigid in compression spring the oil is contained in the closed end of the tube and a floating piston retains the gas in the nose bearing end chamber. When a compressive load is applied to the locked rod, the oil between the piston and the closed end of the tube will not compress and the rod cannot move. Conversely when a tensile force is applied, the gas in the nose section will compress permitting a small amount of movement but again, since the oil in the closed end cannot expand, the movement is less than that experienced with a flexible locking spring.

• Standard design: Release valves are not available for standard rigid in compression gas springs. Due to their construction and the need to provide some lubrication to the rod seal, rigid in compression locking springs can only be used with the rod pointing down.

• High oil fill design: A gas spring built as a flexible locking spring with a high oil fill and an oil chamber will provide a fully rigid in compression function should this be required.

Applications include operating, massage and veterinary tables and wheelchair recline and support systems among many others.