Rigid blockable in compression gas springs

Less widely known, but long-produced gas telescope variety. The lockable, positionable… etc. names are also cover this type. Normally open, compression needs strenght. Can be positioned freely along the full stroke. In blocked state in compression force is rigid, in extension force can be flexible.

Size range:

Within the range shown in the table below, we produce flexible blockable gas springs, even in individual sizes.
The ends of the gas springs are threaded in principle, but can be chosen from a large variety of end fittings as required.

Type	A	B	C	Stroke x F1 max.	D	E
Type	Rod Ø [mm]	Cylinder Ø [mm]	Stroke [mm]	Stroke x F1 max.	Basic lenght calculation [mm]	Extended lenght calculation [mm]
FBCN10	10	22	40 – 500	300 000	(C x2,5) +80	(C x2,5) +80 +G
FBCN10/27	10	27	50 – 500	300 000	(C x2,5) +80	(C x2,5) +80 +G

For each type, the stroke and the maximum value of F1 are determined to avoid bending of the rod. If the gas spring you are looking for exceeds this value, it can only be made with a smaller stroke or force, or it can be made only from bigger type.

The value of G and H are different for each fitting type.

Force characteristics and dampering:

The force of the rigid blockable in compression gas spring is not constant, depending on the position of the piston rod and the direction of movement. The force is required for compression is always greater than the extension froce of the gas spring.

Of the 4 different forces, only one can be definite, preferably the the smallest thrust, F1. This force is called as the force of the gas spring, this is indicated on the nameplate. The F2, F3, F4 force are indicative, may differ from the theoretical values. The force of the gas spring can be affacted by the ambient temperature. When fabricated, the F1 is measured at 20±2 °C. With the change of the temperature, the force change rate is about 3,3% for every 10 °C deviation.

Type	P	Fs max	F1	Max. blocking force		Possible damperings
Type	Progression	Friction force max. [N].	Smallest extension force [N]	Extension [N]	Compression [N]	Extension	Compression	Both direction	Without dampering
FBCN10	2,40	40	50 – 1200	3x F1	7 000	–	–	X	–
FBCN10/27	2,00	50	100 – 1200	5x F1	10 000	–	–	X	–

During the damping of the gas springs, it is the stroke end damping, braking can be mean, which is slows down the speed of movement before reaching the entire open and/or closed lenght, thus saving the structure and the telescope. The rigid blockable in compression gas springs can be ordered with both direction dampering only, due to their internal structure.

The gas spring cannot pick up higher load in compression direction then the maximum load, in extension direction becomes flexible above the specified value. The maximum load in extension direction is the same as the maximum blockin force in compression direction.

Function and structure:

The rigid blockable in compression gas spring is a cylinder filled with high pressure nitrogen, which is divided by the piston rod into two interlocked internal chambers. The piston valve is normally closed. The two sides of the piston, due to the different size surfaces, has differnt force of the gas charge, lower on the lower side than the top. The difference of the two forces is the force of the gas telescope,which pushes the rod outwards. When the valve is closed, the gas does not flow between the chambers, so the gas spring keeps its position. Under external force it is rigid in compression direction, and it moves flexibly in extension direction as the gas is compressible. When the valve is open it acts as a compression gas spring.

Parts of rigid blockable in extension gas spring:
1, release pin 2, piston rod 3, guiding element 4, seal 5, gas and lubrication 6, floating piston 7, piston with valve 8, oil 9, cylinder 10, end fitting