Illustration: Total Coils vs. Active Coils in a Spring

The relationship between total coils and active coils can be understood more clearly with a diagram. Here is a simplified illustration:

1. Total Coils (N₁) – Refers to all coils from one end of the spring to the other, including both support coils and active coils. In this example, the total number of coils is 11.
2. Support Coils (n₂) – The coils at each end that are used for seating or mounting, which generally do not participate in elastic deflection. The number of support coils is typically 1.5, 2, or 2.5 coils per end. In this example, there are 3 support coils at each end, totaling 6 coils.
3. Active Coils (n) – The coils that actually contribute to the spring's elastic deformation, i.e., the coils with uniform pitch. The number of active coils equals the total coils minus the support coils. In this example, active coils = 11 – 6 = 5.

• Total coils (N₁): 11 coils (all coils)
• Support coils (n₂): 6 coils (3 at each end)
• Active coils (n): 5 coils (participate in elastic deflection)

In practice, spring diagrams can be more detailed, but the fundamental principle remains the same.