## Technical Information

## The number of coils

The number of coils in tension springs varies with commercial production as follows:

Number of Coils |
Tolerance |

3 to 5 | ±20° |

6 to 8 | ±30° |

9 to 12 | ±40° |

For each additional coil, add 1½° per coil. Springs can be built to closer tolerances by trimming after coiling, with additional cost.

## Example Load Tolerances

The load tolerances for tension springs are listed in the above table. For example of how to use these, let us take a spring of the following dimensions:

Free Length 4.050”; Mean Dia. .390”; Wire Dia. .048” to give a load of 3.5lb when extended .900”.

Where the line 4.5 intersects with the column of wire dia. of .048” we get a figure of ±10.1%.

This is the load tolerance of the above example.

Convert 10.1% to 3.5 lb. which gives a tolerance of 5.6 oz. at .900” deflection.