Atlas Copco STwrench - Page 311

STwrench User Guide Appendix A – Calculating correction coefficients for extensions
9836 4134 01 Edition 2.9 311 (326)
Warning: The torque correction coefficient alters the STwrench torque measurement; a wrong
value of this coefficient may cause an improper torque reading, generating the risk of executing
a tightening at a different target torque to the one expected. Ensure you have calculated the
proper value when a wrench extension is used. For end-fitting tools used without wrench
extensions, the torque correction coefficient must be left set to 1.
Warning: When using an extension, the torque reading is affected by the hand positioning.
Always place the hand on the middle of the handle of the STwrench:
If a torque multiplier is used on the STwrench, the Torque Correction Coefficient must be set equal to the
torque multiplying coefficient of the torque multiplier.
Torque Correction Coefficient =
input
output
T
T
In the example of figure above, the proper value is 80/10 = 8.
T
input
= 10 Nm
T
output
= 80 Nm