Example A.)

You have an extension spring with a rate (R) of ten pounds per inch and a working load (L) of 20 pounds at a distance traveled (T) of one and a half inches. If you multiply the rate by the distance traveled and subtract the remaining value from the load, you will get the pounds of force of your extension spring’s initial tension as shown in the formula below.

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**IT = L – R(T)**

**IT = Initial Tension**

**L = Load**

**R = Rate**

**T = Travel**

**IT = 20 – 10 * 1.5**

**IT = 20 – 15**

**IT = 5 lbf**

Example B.)

You have an extension spring but aren’t sure of the rate. In this case you would use a load 1 and load 2. Measure the amount of force it takes for your spring to travel a certain distance (L1) and do the same at a larger traveled distance (L2). For this example, your L1 will be of fifteen pounds and L2 will be twenty-five pounds. Multiply your load 1 by 2 and subtract load 2 from the remaining product. This will give you the pounds of force of your extension spring’s initial tension as the formula dictates below.

** **

**IT = 2(L1) – L2**

**IT = Initial Tension**

**L1 = Load 1**

**L2 = Load 2**

**IT = 2(15) – 25**

**IT = 30 – 25**

**IT = 5 lbf**