Double Torsion Springs

Double torsion springs consist of two separate sets of coils wound in opposite directions and connected by a central bridge of wire. This unique design allows them to provide force in both rotational directions, deliver twice the torque output of a single spring, and provide balanced movement for symmetrical loads.
Design and Function
Double torsion springs are designed to store and release angular energy or to hold a mechanism in place by exerting torque.
Dual Coils: They are made from a single piece of continuous wire and feature one right-hand and one left-hand coil section, joined in the middle.
Parallel Operation: Both coil sections work in parallel, meaning the total torque exerted is the sum of the individual torques of each coil. This effectively doubles the force compared to a single torsion spring of the same size.
Bidirectional Force: The opposing wind directions make them ideal for applications requiring rotational precision and motion control in two directions, such as in hinges or levers that need to return to their center position after displacement.
Leg Configurations: The ends (legs) can be custom-designed with various bends, twists, or hooks to facilitate attachment to different components within an assembly.
Materials
The material choice is vital for ensuring strength, durability, and corrosion resistance in demanding operating environments. Common materials include:
High Carbon Steel (e.g., Music Wire ASTM A228): A general-purpose, economical choice with high tensile strength for high-stress applications.
Stainless Steel (e.g., Type 302, 316, 17-7PH): Offers excellent corrosion resistance and performs well over a wide range of temperatures, ideal for medical or marine applications.
Alloy Steels (e.g., Chrome Silicon, Chrome Vanadium): These materials provide superior strength, toughness, and fatigue resistance for heavy-duty, high-stress environments like automotive suspensions.
Non-Ferrous Alloys: Specialty materials such as Beryllium Copper, Phosphor Bronze, or Inconel are used for applications requiring non-magnetic properties, electrical conductivity, or enhanced performance in extreme temperatures.
Common Applications
Due to their ability to provide balanced forces and high torque in compact spaces, double torsion springs are used in many critical and everyday applications.
Automotive Industry: Used in steering columns, seat recliners, throttle controls, and window mechanisms.
Consumer Products: Common in items like clothes pins, clipboards, latches, and self-closing hinges.
Medical Devices: Employed in handheld surgical instruments, diagnostic equipment, and hospital beds that require precise force control and reliability.
Industrial Machinery: Found in clamping devices, counterbalance systems, and automated assemblies requiring precise motion control.
Aerospace: Essential for flight control mechanisms and landing gear components where reliability under demanding conditions is crucial.