Heavy-Duty & Long-lasting Extension Springs

Extension springs, which are also referred to as closed coil helical springs have both their ends attached to different components. When an external force is applied, and the components move apart, and these springs try to bring these components back to their original position. This is why, these springs are also sometimes referred as tension helical springs. To do this, an extension spring absorbs, and holds energy. It creates resistance of equal magnitude as that of the applied force. SMSC provides close wound extension springs of different capabilities and specifications.

Specifications of Extension Springs

The extension springs available with us have following specifications:


Diameter .10 to 6.00 in 2.54 to 152.4 mm
Free Length .25 to 120 inch 6.35 to 3048 mm
Wire Size .010 to .375 in .254 to 9.525 mm
Direction of Winding Right Hand Left Hand Optional
Loop Types Machine Hooks Extended Single Full Loop
Side Hooks Cross Over Double Full Loop
Material Beryllium Copper Music Wire Inconel
Chrome Silicon Chromium Vanadium Phosphor Bronze
Stainless Steel 302 Stainless Steel 304 Stainless Steel 316
Finish Plain Black Oxide Painted
Cadmium Passivate Zinc Gold
Zinc Silver Gold Irridite


Capabilities of Extension Springs

We provide extension springs of following capabilities:

  1. Ends: The different end types of extension springs provided by SMSC are full-loop and machine-made loop configuration. The loops or hooks may have crossways center transition of the previous coil, prior to creating a loop or hook.
  2. Tolerances: Tolerance of an extension spring depends on its wire diameter, and the body diameter. Actual values of tolerances depend on the specifications of these tension helical springs. Generally, the tolerance range of these springs vary between +/-10% and +/-5%.

Types of Extension Springs

We provide different types of mechanical extension springs, which includes:

  1. Continuous Length Extension Springs
  2. Heavy Duty Extension Springs
  3. Round Wire Extension Springs
  4. High Performance Extension Springs

Extension Spring End Types

There are a number of end types of an extension spring. Here are some end types:

  1. Drawbar Spring
  2. V-Hook Over Center
  3. Small Eye at Side
  4. Extended Eye Over Center
  5. Long Round End Hook Over Center
  6. Coned End with Swivel Bolt
  7. Coned End with Swivel Hook
  8. Half Loop Over Center
  9. Full Loop at Side
  10. Machine Half Look Over Center
  11. Small Offset Hook at Side
  12. Double Full Loop at Side
  13. Machine Cut Plain Ends
  14. Single Full Loop Over Center

Extension Spring Shape Types

Extension springs can be designed in various shapes, such as:

  1. Conical
  2. Barrel
  3. Helical
  4. Oval
  5. Cylindrical

Applications of Extension Springs

The closed coil helical springs find their use in a wide range of applications, including:

  1. Garage Doors
  2. Electronic Components and Switches
  3. Automobile Components Manufacturing
  4. Hydraulic and Pneumatic Applications
  5. Oil and Mechanical Seals

The comprehensive stock extension spring catalogue provided by SMSC will help you in selecting the right type of springs for your applications. To know more about different types of extension springs, and also the other types of springs that we provide, please contact at the earliest. You can reach out to us on our toll-free number 800-330-2460, or mail us your requirements at smsc@windstream.net.

 Related Blog Post: