A click torque wrench is used to fasten a bolt or nut that may require a specific amount of torque. The most common form of this is a socket wrench. The very first was developed in 1918 as it was needed by the New York City water department. This tool is very important when the tightness of the bolts or screw is vitally important. Many times specific bolts will need to match specifications in order for the tool to work properly. An engineer will have determined how much give is needed in the blot for maximum life application and minimal wear.
Step 1. The Specification
You will need to find what specification the bolt or screw you are using requires. This is necessary so you tighten the fastener to the correct point. You can then set the wrench to the correct torque setting. The wrench will have a roll dial that is used to set the needed torque specification.
Step 2. The Fastener
Before you use the torque wrench, you want to thread the fastener, normally a bolt or screw, by hand. You do not need to get this hand tight. Just make sure it is securely on the threads. Attach the socket to the torque wrench.
Step 3. Tightening the Fastener
Now that the wrench and fastener are in place, you can place the socket head over the fastener head. You cannot use the wrench quickly because it is important that you tighten the bolt slowly. As the bolt becomes tighter you will find the wrench turns slower. It is important to pull smoothly. If you jerk the wrench then you may cause the wrench to click too early as you are making the pivot point break too early.
Step 4. The Click
When you hear a click from the wrench, it will have reached the correct torque. This click is not overly loud and many people feel the click rather than hear it. At this point your bolt has been tightened to the specified tightness. If you go past the click then you will have over tightened the fastener which can cause problems. The click occurs when the pivot point and the handle grip have reached the breaking force.
Step 5. A Sequence of Bolts
Many times there will be more than one bolt to bring the two materials together. The sequence in which you tighten the bolts is important. You want to check with what the directions say. Many times going in a criss cross pattern is good. If you start on a bolt and tighten them in a circular order you can cause the part to crack and damage. Think about changing a tire on your car. You must tighten the bolts in a criss cross pattern.
Step 6. Going too Far
If you have gone past the click, then you will need to unscrew the bolt and then retighten it to the correct tightness. Many times you will find that the fastener cannot go past the required tightness as it will become very difficult to turn the wrench. However many times this point will not be completely tight as the pipe or object may swell with use and the tightness of the fastener will take this into account.