A Torque Wrench is a tool used to precisely apply a specific torque to
a fastener such as a nut or bolt. It is usually in the form of a socket wrench
with special internal mechanisms. It was invented by Conrad Bahr in 1918 while
working for the New York City Water Department. It was designed to prevent
overtightening bolts on water main and steam pipe repairs underground.
A torque wrench is used where the tightness of screws and bolts is crucial. It allows the operator to measure the torque applied to the fastener so it can be matched to the specifications for a particular application. This permits proper tension and loading of all parts. A torque wrench measures torque as a proxy for bolt tension. The technique suffers from inaccuracy due to inconsistent or uncalibrated friction between the fastener and its mating hole. Measuring bolt tension (bolt stretch) is more accurate but often torque is the only practical means of measurement.
Torque screwdrivers and torque wrenches have similar purposes and mechanisms.
Beam type torque wrench. The indicator bar remains straight while the main shaft bends proportionally to the force applied at the handle.Detailed view of the torque display scale on a beam type torque wrench. This shows a torque of about 160 inch-pounds force or 18 N·m.The simplest form of torque wrench consists of a long lever arm between the handle and the wrench head, made of a material which bends elastically in response to applied torque. A second, smaller bar with integral mechanical indicator is also connected to the head; this is never subjected to torque and thus maintains a constant position with respect to the head. When no torque is applied to the lever arm the indicator rests parallel to the lever arm. A calibrated scale is fitted to the handle so that applied torque, and the associated bending of the main lever, causes the scale to move under the indicator. When the desired torque is reached (as shown by the indicator), the operator stops applying force. This type of wrench is simple, inherently accurate, and inexpensive.
The beam type torque wrenches was developed in the late 1920s/early 1930s by Walter Percy Chrysler for the Chrysler Corporation and a company known as Micromatic Hone. Paul Allen Sturtevant—a sales representative for the Cedar Rapids Engineering Company at that time—was licensed by Chrysler to manufacture his invention. Sturtevant patented the torque wrench in 1938 and became the first individual to sell torque wrenches.
A more sophisticated variation of the beam type torque wrench has a dial gauge indicator on its body that can be configured to give a visual indication, or electrical indication, or both when a preset torque is reached.
Deflecting beam
The dual-signal deflecting beam torque wrench was patented by the Australian Warren and Brown company in 1948. It employs the principle of applying torque to a deflecting beam rather than a coil spring. This helps prolong wrench life, with a greater safety margin on maximum loading and provides more consistent and accurate readings throughout the range of each wrench. The operator can see and hear when a dual-signal wrench reaches the selected torque, since the signal can be seen and heard.
Click type
A more sophisticated method of presetting torque is with a calibrated clutch
mechanism. At the point where the desired torque is reached, the clutch slips,
signaling the desired torque and preventing additional tightening. The most
common form uses a ball detent and spring, with the spring preloaded by an
adjustable screw thread, calibrated in torque units. The ball detent transmits
force until the preset torque is reached, at which point the force exerted by
the spring is overcome and the ball clicks out of its socket. The advantage of
this design is greater precision and a positive action at the set point. A
number of variations of this design exist for different applications and
different torque ranges eg Torque-Wrenches Inch Pounds. A modification of
this design is used in some drills to prevent gouging the heads of screws while
tightening them.
No-hub wrench
This is a specialized torque wrench used by plumbers to tighten the clamping bands on hubless soil pipe couplings. It is a T-handled wrench with a one-way combination ratchet and clutch, factory calibrated to slip at a torque sufficient to seal the coupling, but insufficient to damage it. Since the ratchet is not reversible, the shaft of the wrench incorporates a folding auxiliary handle for loosening the clamps.
Programmable electronic torque / angle wrenches
Torque measurement is conducted in the same way as with an electronic torque wrench but the tightening angle from the snug point or threshold is also measured. The angle is measured by an angle sensor or electronic gyroscope. The angle measurement process enables joints which have already been tightened to be recognised. The inbuilt readings memory enables measurements to be statistically evaluated. Tightening curves can be analysed using the software via the integrated tightening-curve system (force/path graph). This type of torque wrench can also be used to determine breakaway torque, prevail torque and the final torque of a tightening job. Thanks to a special measuring process, it is also possible to display the yield point (yield controlled tightening). This design of torque wrench is highly popular with automotive manufacturers for documenting tightening processes requiring both torque and angle control because, in these cases, a defined angle has to be applied to the fastener on top of the prescribed torque (e.g. 50 N·m or 37 lbf·ft + 90° - here the 50 N·m or 37 lbf·ft means the snug point/threshold and +90° indicates that an additional angle has to be applied after the threshold).
Saltus-Werk Max Forst GmbH applied in 1995 for an international patent for the first electronic torque wrench with angle measurement which did not require a reference arm.
Mechatronic torque wrenches
Torque measurement is achieved in the same way as with a click-type torque wrench but, at the same time, the torque is measured as a digital reading (click and final torque) as with an electronic torque wrench or Digital Torque Wrench. This is, therefore, a combination of electronic and mechanical measurements. All the torque wrench measurements are transferred and documented via wireless data transmission.
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A torque wrench is used where the tightness of screws and bolts is crucial. It allows the operator to measure the torque applied to the fastener so it can be matched to the specifications for a particular application. This permits proper tension and loading of all parts. A torque wrench measures torque as a proxy for bolt tension. The technique suffers from inaccuracy due to inconsistent or uncalibrated friction between the fastener and its mating hole. Measuring bolt tension (bolt stretch) is more accurate but often torque is the only practical means of measurement.
Torque screwdrivers and torque wrenches have similar purposes and mechanisms.
Beam type torque wrench. The indicator bar remains straight while the main shaft bends proportionally to the force applied at the handle.Detailed view of the torque display scale on a beam type torque wrench. This shows a torque of about 160 inch-pounds force or 18 N·m.The simplest form of torque wrench consists of a long lever arm between the handle and the wrench head, made of a material which bends elastically in response to applied torque. A second, smaller bar with integral mechanical indicator is also connected to the head; this is never subjected to torque and thus maintains a constant position with respect to the head. When no torque is applied to the lever arm the indicator rests parallel to the lever arm. A calibrated scale is fitted to the handle so that applied torque, and the associated bending of the main lever, causes the scale to move under the indicator. When the desired torque is reached (as shown by the indicator), the operator stops applying force. This type of wrench is simple, inherently accurate, and inexpensive.
The beam type torque wrenches was developed in the late 1920s/early 1930s by Walter Percy Chrysler for the Chrysler Corporation and a company known as Micromatic Hone. Paul Allen Sturtevant—a sales representative for the Cedar Rapids Engineering Company at that time—was licensed by Chrysler to manufacture his invention. Sturtevant patented the torque wrench in 1938 and became the first individual to sell torque wrenches.
A more sophisticated variation of the beam type torque wrench has a dial gauge indicator on its body that can be configured to give a visual indication, or electrical indication, or both when a preset torque is reached.
Deflecting beam
The dual-signal deflecting beam torque wrench was patented by the Australian Warren and Brown company in 1948. It employs the principle of applying torque to a deflecting beam rather than a coil spring. This helps prolong wrench life, with a greater safety margin on maximum loading and provides more consistent and accurate readings throughout the range of each wrench. The operator can see and hear when a dual-signal wrench reaches the selected torque, since the signal can be seen and heard.
Click type
No-hub wrench
This is a specialized torque wrench used by plumbers to tighten the clamping bands on hubless soil pipe couplings. It is a T-handled wrench with a one-way combination ratchet and clutch, factory calibrated to slip at a torque sufficient to seal the coupling, but insufficient to damage it. Since the ratchet is not reversible, the shaft of the wrench incorporates a folding auxiliary handle for loosening the clamps.
Electronic torque wrenches
With electronic (indicating) torque wrenches, measurement is by means of a strain gauge attached to the torsion rod. The signal generated is converted by the transducer to the required unit of force (N·m, lbf·ft etc.) and shown on the digital display. A number of different joints (measurement details or limit values) can be stored. These programmed limit values are then permanently displayed during the tightening process by means of LEDs or the display. At the same time, this generation of torque wrenches can store all the measurements made in an internal readings memory. This readings memory can then be easily transferred to a PC via the interface (RS232) or printed straight to a printer. A popular application of this kind of torque wrench is for in-process documentation or quality assurance purposes.Programmable electronic torque / angle wrenches
Torque measurement is conducted in the same way as with an electronic torque wrench but the tightening angle from the snug point or threshold is also measured. The angle is measured by an angle sensor or electronic gyroscope. The angle measurement process enables joints which have already been tightened to be recognised. The inbuilt readings memory enables measurements to be statistically evaluated. Tightening curves can be analysed using the software via the integrated tightening-curve system (force/path graph). This type of torque wrench can also be used to determine breakaway torque, prevail torque and the final torque of a tightening job. Thanks to a special measuring process, it is also possible to display the yield point (yield controlled tightening). This design of torque wrench is highly popular with automotive manufacturers for documenting tightening processes requiring both torque and angle control because, in these cases, a defined angle has to be applied to the fastener on top of the prescribed torque (e.g. 50 N·m or 37 lbf·ft + 90° - here the 50 N·m or 37 lbf·ft means the snug point/threshold and +90° indicates that an additional angle has to be applied after the threshold).
Saltus-Werk Max Forst GmbH applied in 1995 for an international patent for the first electronic torque wrench with angle measurement which did not require a reference arm.
Mechatronic torque wrenches
Torque measurement is achieved in the same way as with a click-type torque wrench but, at the same time, the torque is measured as a digital reading (click and final torque) as with an electronic torque wrench or Digital Torque Wrench. This is, therefore, a combination of electronic and mechanical measurements. All the torque wrench measurements are transferred and documented via wireless data transmission.
For Information check
Official Website :- http://mytoolsgallery.com/
Facebook Page :- https://www.facebook.com/My-Tools-Gallery-411673565834462/
Twitter :- https://twitter.com/mytoolsgallery
