Extension Springs are springs which absorb and store energy by offering resistance to
a pulling force . Typically, extension springs are made from round wire and are close wound with initial tension. Extension applications include tape cassette players, balance scales, garage doors, washing machines and applications which requiring various types of tensioning devices. Various types of ends are used to attach the extension spring to the source of the force.
In Ordering Give the Following Information as Completely as Possible:
- Length, Maximum, Minimum, (Over all, Over coil, Inside Hooks).
- Controlling Diameter: Outside Diameter Maximum. Inside Diameter Minimum.
- Wire Size. Decimal size if Possible. Material, Kind and Grade.
- Number of Coils.
- Style of Ends - Right or Left Hand Wound.
- Finish (Plain unless otherwise specified).
- Load Required, Length Inside Hooks (Length of Coil if wire size not specified).
- Maximum Extended Length (Over all, Over coil, Inside Hooks).
- Deflection or Distance of Travel. Frequency of Extension.
Measuring Rate
- Extend spring to a length (L1) such that definite coil separation occurs and measure the load (P1).
- Extend spring further to a second length (L2) and again measure the load (P2).
- Calculate rate by dividing the load difference by the length difference in: R = (P2 - P1)/(L2- L1)
Measuring Initial Tension
1 Establish exact initial length (Li) of spring by applying enough load to get slack out but not enough to separate coils.
2 Extend spring to length (L1) sufficient to open coils and measure load (P1).
3 Extend spring to length (L2) such that second deflection equals first deflection and measure load (P2).
Since the two deflections are equal, proof can be shown that initial tension is as follows:Pi = 2P1 - P2
Material:
- Music Wire per ASTM A228, DIN 17223 or JIS-G-3522
- Stainless Steel Type 301/302/304 OR Type 316 per ASTM A313, DIN 17224,or JIS-G-4314
- Oil Tempered MB per ASTM A229, DIN 17223
- Oil Tempered Chrome Silicon per ASTM A401, DIN 17223
Special material are also available upon request.