Terms, Definitions of lockable gas spring
3. Terms, Definitions, Symbols, and Explanations
The terms, definitions, symbols, and explanations established in GB/T 1805 and Table 1 apply to this standard.
| Term | Definition or Explanation | Symbol | Unit |
| Gas spring | An elastic element composed of a sealed cylinder barrel, a piston that can slide inside the cylinder barrel, and a piston rod assembly, using nitrogen or other inert gases as the energy – storage medium. Note: Adapted from GB/T 1805—2001, Definition 2.9 | ||
| Lockable gas spring | A gas spring that can be locked or unlocked at any position within its movement stroke | ||
| Piston rod diameter | The diameter of the piston rod of a gas spring [GB/T 1805—2001, Definition 3.111] | d | mm |
| Cylinder inner diameter | The inner diameter of the cylinder barrel of a gas spring | D1 | mm |
| Cylinder outer diameter | The outer diameter of the cylinder barrel of a gas spring [GB/T 1805—2001, Definition 3.110] | D2 | mm |
| Stroke | The axial displacement of the piston rod from the fully extended state to the state when compressed to the minimum size | S | mm |
| Extended length | The effective length of a gas spring in the fully extended state | L | mm |
| Unlocking force | The force required to release the locked state of a gas spring and open the valve | Fk | N |
| Start – up force | The initial force required to press the piston rod after opening the valve, when the gas spring has been in the extended state for a certain period of time [GB/T 1805—2001, Definition 3.116] | F0 | N |
| One cycle | The piston rod is compressed and extended once each according to the specified stroke | ||
| Extension speed | The average speed at which the piston rod freely extends from the end of the specified stroke to the initial position | v – | mm/s |
| Specified force | The force marked on the product drawings and products confirmed by both the supplier and the demander (F1, Fa, F3, …) | F× | N |
| Minimum extension force | The force measured at the specified force – taking point C near the starting point of the working stroke during the extension process. Note: Adapted from GB/T 1805—2001, Definition 3.119 | F1 | N |
| Maximum extension force | The force measured at the specified force – taking point C near the end point of the working stroke during the extension process. Note: Adapted from GB/T 1805—2001, Definition 3.120 | F2 | N |
| Minimum compression force | The force measured at the specified force – taking point C near the starting point of the working stroke during the compression process. Note: Adapted from GB/T 1805—2001, Definition 3.121 | F3 | N |
| Maximum compression force | The force measured at the specified force – taking point C near the end point of the working stroke during the compression process. Note: Adapted from GB/T 1805—2001, Definition 3.122 | F4 | N |
| Nominal force a | One of the comprehensive characteristic indicators of a gas spring. It is the average value of the maximum extension force and the minimum compression force, i.e., Fa=(F1 + F3)/2. Note: Adapted from GB/T 1805—2001, Definition 3.123 | Fa | N |
| Nominal force b | The average value of the minimum extension force and the maximum compression force, i.e., Fb=(F2 + F4)/2. Nominal force b is generally used for calculating the force ratio | Fb | N |
| Dynamic friction force | The average value of the difference between the minimum compression force and the minimum extension force, i.e., Fr=(F3 – F1)/2. Note: Adapted from GB/T 1805—2001, Definition 3.124 | Fr | N |
| Force ratio | The ratio of nominal force b to nominal force a, i.e., α = Fb/Fa. Note: Adapted from GB/T 1805—2001, Definition 3.125 | α | |
| Rigid locking | In the locked state, when a gas spring is under the action of axial compression and tension forces, the piston rod generates displacement, and its force – displacement characteristic curve is as follows. | ||
| Elastic locking | In the locked state, when the displacement of the piston rod of a gas spring under the action of compression or tension forces is not more than 2mm, it can reach the agreed locking force (see Curves I and II). In the locked state, when the piston rod of a gas spring under the action of compression or tension forces generates a relatively large displacement (see Curve III) | ||
| Locking force | The axial compression or tension force required to cause a certain displacement of the piston rod when the gas spring is in the locked state | Fs | N |
| Force – taking point | The point for collecting force values during dynamic or static testing | C | mm |
Technical Specification for Lockable Gas Springs (English version of national strandard, initiated by LeiYan Gas Springs), proposed and prepared by SAC/TC 235 (National Technical Committee 235 on Spring of Standardization Administration of China).
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