Adding an adapter to a torque wrench

Use of Adapter

Formula:
TA x L
L + A
= TW
Length (L) =
Effective length of the wrench as described below.
Dial Wrenches =
The measured distance from the center of the square drive to the center ring or notch on the handle.
Micrometer Wrenches =
The measured length from the center of the square drive to the center of the handle, with the wrench set at the desired torque reading.
Desired Torque (TA) =
The torque value designated for the fastener with or without an adapter.
Added Length of Adapter (A) =
The measured length from the center of the adapter drive to the center of the wrench square drive.
New Setting (TW) =
The torque setting on the wrench allowing for the added length of the adapter. This reading will be lower than the desired torque.
Example:
250 ft. lb. Dial Wrench using a 2” long crowfoot adapter

L = Effective Length: 18.75”
Desired Torque = 250 ft. lb.
Length of Adapter = 2”
Result:
18.75" x 250 ft. lb.
18.75" + 2"
= Pull Wrench to 226 ft. lb.