Contorque® Constant Torque Springs

Vulcan Spring is a leading designer and manufacturer of constant torque springs, also called constant rotational tension springs. Contorque® is Vulcan Spring's brand name for its constant torque spring, a brand that is well known and highly respected for quality throughout the world. Contorque® constant torque springs.

  • Offer high amounts of torque with very small space requirements
  • Can also be designed to produce positive or negative gradient output torque

Custom Constant Torque Springs

Vulcan Spring specializes in making custom constant torque springs to customer specification. With Vulcan Spring’s design, engineering and manufacturing prowess, custom springs can be produced in almost the same time as stock springs. “Custom” is normal for Vulcan Spring and this has been proven to customers over and over again.

How to Work with Vulcan Spring for Custom Constant Torque Springs

Vulcan Spring works with our clients at various stages of their product development process with DFM (design for manufacturing) principles. We are design experts with over 40 years' experience in designing and delivering cost effective products in volume. In addition, Vulcan offers a broad range of fully engineered springs from our extensive portfolio of products.

The design and engineering process includes:Constant Torque Spring Specs

  • Initial Design Review
  • Prototyping
  • Testing
  • Production – Short run or long run production

Technical Considerations for Constant Torque Springs

Constant torque springs are typically specified and engineered with the following in mind:

  • Torque requirements - the torque of the spring should be equal to the requirement of the application. The normal tolerance for a constant torque spring is +/-10%.
  • Number of working or usable turns.
  • Available space - for proper operation, leave +10% calculated according to material thickness, life, and torque required.
  • Minimum spool spacing calculation - the distance between spool centers (dimension "S") must be greater than the radius of the spring when fully wound on the storage spool, plus the radius of the spring when fully wound on the outpost spool
  • Size
    • Maximum width
    • Maximum outside diameter (O.D.)
    • Output drum diameter
  • Length - Allow at least 1 1/2 turns to remain on the storage spool when the spring is fully wound, and 1 1/2 turns to remain on the output spool when the spring is unwound. The formula for determining length (L) is as follows: L = πN (Do + Nt) + 10 Do. This formula takes into account: diameter buildup, number of revolutions (N), thickness of material (t) and output spool diameter (Do)
  • End detail - Vulcan Spring has many standard dies to create the end detail; the image shows some that are available. Special end designs can be made for a normal charge

   View End Details  

Constant torque specifications


Applications / Uses for Constant Torque Springs

Contorque® constant torque springs are ideal for a wide variety of uses where constant torque / tension springs are needed, including applications requiring smooth returning and retrieving, counterbalancing applications, and tensioning and loading applications. Industries that use constant torque springs include:

In some applications, it is desirable for the spring to change force. A spring that produces less force while being extended has a negative gradient. A spring that produces more force when extended has a positive gradient. Vulcan Spring offers both positive gradient torque springs and negative gradient torque springs.

Vulcan Spring’s Manufacturing Process for Constant Torque Springs

Vulcan Spring utilizes highly customized production equipment, lean manufacturing techniques and principles, and ISO 9001:2015 certified procedures to provide our customers with a streamlined and efficient manufacturing process.

Benefits of working with Vulcan Spring include reduced lead times, high quality control and highly competitive costs.

Contact Vulcan Spring for Custom Constant Torque Springs

Complete the Contorque® constant torque spring specification form for further assistance with custom constant torque springs from Vulcan Spring.


single spring motor

retraction of torque spring

multiple contorque motor assembly