A wrench that is applied in setting the torque of a fastening, like a nut or a bolt to a great degree of precision is called a torque wrench. It is actually a socket wrench that uses special mechanisms and is of great use where you need to be absolutely sure about the tightness of the screws and the bolts. You can measure how much torque is applied so that you are sure that the tightness is up to the specifications. So, you can ensure that there is proper loading and tension of all the parts. So indirectly, it is measuring bolt tension. However, thanks to the friction between the mating hole and the fastener, this technique does suffer from inaccuracy sometimes. So it is better to measure the bolt tension or the bolt stretch and often, the only measurement that is possible and accurate is torque. Here are different types of torque wenches.
A Beam Torque Wrench is made up of a long lever arm between the handle and the head. Moreover it is made up of a material that bends elastically when some torque is applied on it as you can see online at http://toptorquewrench.com/. A smaller bar with an indicator is connected to the back of the head of wrench. It is kept in parallel to the lever arm of the wrench. This smaller bar which is connected to the wrench does not come under any type of strain and so remains straight. Along with such arrangement there is a calibrated scale which is fitted to the handle. This scale is moved under the indicator when the main lever is bent. The operator or the user stops applying the force once the indicated level of torque is achieved. Such a type of arrangement makes the torque wrench to perform very accurately and steadily. Along with this, it is very simple to use and inexpensive.
A deflecting beam wrench is also known as a dual-signal deflecting beam. Such torque wrench works on by applying torque to a deflecting beam and not on a coil spring. With such principle of working the life of the wrench is increased along with a bigger safety margin. It gives the ability of maximum loading over the wrench. Such step helps the user to gain efficient, accurate and consistent readings. The operator or the user can get the full control over the wrench as he or she can see and hear when the dual-signal reaches the specific level of torque.
In this mechanism, employing a calibrated clutch is an effective method to preset the torque. In such type of mechanism the clutch slips when a particular level of torque is reached. This level of torque is decided by the operator and thus helps in preventing the additional tightening. The most common type of wrench in this category is a detent ball and a spring. The spring is preloaded by the use of a screw thread which is calibrated in different torque units. In this application the force is transmitted by the ball until the specific torque is reached. As soon as this specific torque is reached, the force is exerted then the spring overcomes it and the ball comes out of the socket. Such design gives higher precision and accurate result. There are large numbers of design variations available in the market depending on its application and the torque ranges.
A No-hub wrench is a special kind of a wrench as compared to variety of wrenches available today. Such wrenches are applied in soil pipe couplings by the plumbers when tightening the clamping bands. “No – hub” wrench is a T-handled wrench having a one way combination clutch and ratchet. The shaft of such wrench comes with a folding handle which is used to loosen the clamps.