An electronic torque wrench for driving a workpiece includes a wrench body having a handle end and a wrench head receiving end. A wrench head a workpiece receiving end and a mounting end, and the mounting end is removably received by wrench head receiving end. A user interface having a processor and a display is mounted on the wrench body. A wrench head sensing device is carried by the wrench head receiving end and includes an electrical connection between the wrench head sensing device and the processor. The wrench head sensing device sends an electrical signal to the processor indicating the presence of the wrench head on the wrench head receiving end.
An electronic torque wrench includes a tubular housing having a receiving space, a working unit having an abutment portion extending into the receiving space, a strain sensor provided in the working unit, and a trip unit disposed in the receiving space and including a cylinder having a chamber containing hydraulic fluid, a trip element disposed movably between the abutment portion and the cylinder and having a seat portion, and a control element connected to the cylinder for pressurizing or depressurizing the hydraulic fluid so as to permit the abutment portion to be seated on or to move away from a center of the seat portion. A central processor is connected electrically to the strain sensor and the control element, and controls the control element to depressurize the hydraulic fluid when an applied torque measured by the strain sensor is larger than a preset reference torque value.
