Thursday, November 7, 2013
Torque Wrench Specifications
A torque wrench provides a mechanic exact tightness capability when using the tool as a socket wrench. This feature is particularly important when working on engines and similar assemblies that must have factory-setting tightness on various nuts and bolts holding parts together. Too much and the threads in the engine casings could strip. Too little and the parts can come loose or cause leaks, deteriorating engine performance. Using a torque wrench ensures the assembly work is done right the first time. However, torque wrenches come in different types, some being better than others when it comes to exact measurements.
The Beam Type
Beam-type torque wrenches represent the bargain-bin version of the tool. Their cost is relatively low but the exact measurements are usually off or hard to keep correct.
The beam wrench uses a long lever that bends as the wrench is tightened. This bending triggers a mechanism in the tool that compares to another lever that stays the same regardless of the tool being used. As the first beam moves away from the second, the user can, in theory, measure the torque being applied.
The quality of the beam tool is questionable. Even if it works correctly, getting an exact tightness is hard since you have to eyeball the tightness on the lever display and guestimate when you are at the correct pressure.
The Dial Version
The dial version uses a mechanism similar to that in a beam wrench. However, with the dial version the pressure exerted is translated to a dial at the top of the wrench near the handle which displays the pressure relative to a dial chart. The tighter the wrench is pulled, the more the dial moves to reflect the torque measurement. This version also relies on a human eye to determine when to stop.
Electronic dial wrenches use the same approach but display the torque setting digitally. At least in these versions the human eye is taken out of the equation. The simple computer in the wrench displays the torque readings produced when using the wrench.
The Clicker Type
Long reputed as the correct torque wrench to use for engine applications, the click-type wrench has a mechanism that actually pops in the wrench when the correct tightness is applied. This click signals to the user to stop tightening.
Preset measurements are cast on the side of the handle to adjust the wrench for a desired tightness. Then the wrench is applied and the mechanism clicks when the preset torque is reached.
These tools are typically cast in all metal, similar to a normal socket wrench, and come in protective cases to avoid impact or banging which can disrupt the tools accuracy settings.
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