The majority of springs in operation today are linear springs, meaning that the force required to push or pull them out of a resting state increases linearly with the amount of deformation. Linear springs’ forces can be mapped with the equation F=kX, with k being the spring constant and X being the length of deformation. Variable diameter springs are a category of springs that often don’t follow these rules. This in itself can be advantageous to manufacturers in certain cases, but a number of other properties make variable diameter springs necessary for a range of products.

Potential advantages include:

  • Adjustability of force required to compress the spring
  • Increase in travel because one coil can fit into the other
  • Decrease in “solid height,” or height of the spring at full compression
  • Greater lateral stability for longer springs

Variable diameter springs include conical springshourglass springs and barrel springs.

  • Conical springs are wider at one end than the other, and are also known as tapered springs.
  • Hourglass springs, or concave springs, are wider at both ends and narrower in the middle.
  • Barrel springs, or convex springs, are wider in the middle and narrower on both ends.

Examples of Products Using Variable Diameter Springs

  • Battery compartments
    Open your remote control and you’ll most likely find a number of battery compartments with coiled springs at one end. Conical springs are often used in small spaces like this because they can compress down to the height of their wire diameter.
  • Firearm Triggering Mechanisms
    Because of their ability to modulate force and avoid buckling, conical and barrel springs can offer more precise control over triggering mechanisms.
  • High-End Mattresses
    Mattresses advertising “pocket coils” often utilize individually wrapped barrel springs to provide support to sleepers. Other mattresses utilize hourglass springs, which are intended to flex laterally to provide support from any angle.
  • Automotive Suspension
    Barrel springs, hourglass springs and conical springs are often used in automotive suspension systems, both because of their ability to compress without buckling and increase travel through coil telescoping.

Contact Acme Wire Products today to answer your questions and provide you with a custom quote today.


Acme Wire Products has designed, recommended, and manufactured custom wire components for customers in many diverse markets.  We offer the benefit of our almost 50 years of experience in the manufacture of component parts for hardware, medical & lab equipment, cable management, sporting goods, firearms, furniture, guarding, HVAC,  pharmaceutical, automotive, optical, and food service, and processing industries.

Acme Wire’s designers work with our customers to create a wire component that will provide the greatest functional value.  The design of wire products such as levers, handles, supports, rings, guards, baskets, trays, grids, frames, and shelves is limited only by one’s imagination (and the limitations of technology).

Contact Acme Wire Products to assist you in determining the wire product best suited to your requirements!    Call Acme Wire Products at 1-800-723-7015 to get started.

Acme Wire Products Co., Inc.  – Mystic, CT


Fax – 860-572-9456