Terminology Common to All Springs
Active Coils – The coils which are free to deflect when the spring is loaded.
Total Coils – All coils including the end coils.
Counting Coils – Look at the end of the spring, turn the spring the wire is at 12.00 o’clock, follow the wire round, each time the wire passes 12.00 o’clock it is a complete coil, when reaching the last full coil stop and estimate the remaining wire ie, ¼, ½ or ¾ etc. then add this to the number of full coils.
Spring Hand – The direction in which the spring is wound, Right or Left Hand.
Right of Left Hand – Look at the end of the spring, turn the spring so the start of the wire is at 12.00 o’clock, if the direction of the wire is to the right the spring is Right Hand (R/H), if the direction of the wire is to the left the spring is Left Hand (L/H).
Mean Coil Diameter – Outside spring diameter (O/D) less one wire diameter.
Deflection – Movement of ends of spring when a load is applied.
Rate – Change in load per unit deflection, normally given as pounds per inch (lbs/in) or Newton’s per millimetre (N/mm).
Load – Pressure at a given deflection.