Figure 1-34.—Torque wrenches

The three most commonly used torque wrenches are the deflecting beam, dial indicating, and micrometer setting types (fig. 1-34). When using the deflecting beam and the dial indicating torque wrenches, read the torque visually on a dial or scale mounted on the handle of the wrench. To use the micrometer setting type, unlock the grip and adjust the handle to the desired setting on the micrometer-type scale, then relock the grip. Install the required socket or adapter to the square drive of the handle. Place the wrench assembly on the nut or bolt and pull in a clockwise direction with a smooth, steady motion. (A fast or jerky motion will result in an improperly torqued unit.) When the torque applied reaches the torque value, which is indicated on the handle setting, a signal mechanism will automatically issue an audible click, and the handle will release or "break," and move freely for a short distance. The release and free travel is easily felt, so there is no doubt about when the torquing process is complete. Manufacturers' and technical manuals generally specify the amount of torque to the applied. To assure getting the correct amount of torque on the fasteners, it is important that the wrench be used properly according to manufacturer's instructions. Use the torque wrench that will read about mid-range for the amount of torque to be applied. BE SURE THE TORQUE WRENCH HAS BEEN CALIBRATED BEFORE YOU USE IT. Remember, too, that the accuracy of torque-measuring depends a lot on how the threads are cut and the cleanliness of the threads. Make sure you inspect and clean the threads. If the manufacturer specifies a thread lubricant, it must be used to obtain the most accurate torque reading. When using the deflecting beam or dial indicating wrenches, hold the torque at the desired value until the reading is steady. Torque wrenches are delicate and expensive tools. The following precautions should be observed when using them: 1. When using the micrometer setting type, do not move the setting handle below the lowest torque setting. However, it should be placed at its lowest setting before it is returned to storage. 2. Do not use the torque wrench to apply greater amounts of torque than its rated capacity. 3. Do not use the torque wrench to loosen bolts that have been previously tightened. 4. Do not drop the wrench. If a torque wrench is dropped, its accuracy will be affected. 5. Do not apply a torque wrench to a nut that has been tightened. Back off the nut one turn with a nontorque wrench and retighten to the correct torque with the indicating torque wrench. 6. Calibration intervals have been established for all torque tools used in the Navy. When a tool is calibrated by a qualified calibration activity at a shipyard, tender, or repair ship, a label showing the next calibration due date is attached to the handle. This date should be checked before a torque tool is used to ensure that it is not overdue for calibration. 1-24 Figure 1-34.—Torque wrenches.